Natural science
Science - this term has been derived from a Greek verb scire, meaning to know and a Latin noun scientia, meaning knowledge. It is an orderly and systematized body of knowledge based on observations, reasoning and experimental verification. The scientific knowledge is gathered by observations, inquiry and investigations. The main thing that distinguishes science from humanities such as art and culture is the use of the experiments to answer the questions.
The scientific reasoning and the experiments are often simple not mysterious at all. They are merely logical ways of trying to answer the problem as are used by business people, historians and each of us in everyday life. There is no need of any scientific training or knowledge to decide whether conclusions are justified from the data presented or not. We can request further tests of a theory that not appear to be well supported by evidence, and we can agree or disagree with the predictions from a theory.
The term science when used without any descriptive adjective refers to natural science. It deals with natural phenomena. It is different from social science such as sociology which deals with human relations or an abstract science such mathematics which deals with abstract relations.
Natural science is taken into a position of great importance in modern society. Scientific inventions and discoveries are inseparable from human life and welfare. Their applications in day to day problem provide solutions for them. Many decisions affecting our future depend on appropriate interpretation of scientific discoveries.
The government of a country requires that every one participate in decisions on such subjects as population control, pollution standards, protection of wildlife and immunization. The body of scientific knowledge is already so vast that everyone can not understand it all. However, as a responsible citizen, we can follow some studies that bear on public issues. By doing so, we can apply scientific reasoning to decide our own positions on these issues.
However, the natural sciences can be categorized into physical sciences and biological sciences. The physical sciences primarily deal with non-living matter and include subjects like Physics, Chemistry, geology, astronomy etc. The biological sciences include the living organisms, their interactions and relationship with the non – living things. It includes the subjects like Botany, Zoology and microbiology etc.
Scientific Method
The knowledge imparted by any science includes facts, laws and principles of the nature. The knowledge about these is acquired by a typical procedure which is sometimes called scientific method or method of science. This method is used to know about an unknown object or an unknown happening (event or phenomenon) in any science. Sequence of steps of this procedure are broadly classified as
• Observation
• Hypothesis
• Experimentation
• Conclusion
• Sometimes retesting
The scientific method begins with a set of observations with respect to an unknown object or an unknown happening (event or phenomenon) the set of observations activate observer’s (scientist’s or researcher’s ) mind and he wants to know about the unknown object or unknown happening. His natural reaction is to ask questions about it. Then considering his own thought, colleagues’ suggestion and information of the literature, he recognizes a problem to investigate on his observations.
With these information, the scientist or researcher puts forth a hypothesis. Hypothesis is an explanation of what he expects in the underlying original observation or a set or observations. The hypothesis is a tentative explanation or observations or event. It is confirmed through the experiment or refused.
The hypothesis is tested through experiment. It is called experimentation. The experiment is carried out in a specified fashion. The scientist attempts to hold all conditions constant except the one he is manipulating so that any result he observes should be exclusive function of the changed conditions. The result is compared with that of a control, an experiment that depicted all natural conditions.
From the data of experiment, a conclusion is arrived at. If the conclusion is contrary to the hypothesis the hypothesis is refuted, otherwise the conclusion establishes a fact law or principle about the unknown object or happening.
Physics, major science, dealing with the fundamental constituents of the universe, the forces they exert on one another, and the results produced by these forces. Sometimes in modern physics a more sophisticated approach is taken that incorporates elements of the three areas listed above; it relates to the laws of symmetry and conservation, such as those pertaining to energy, momentum, charge, and parity. See Atom; Energy.
Scopes of Natural Science
Divisible into pure science and applied science
Study , understanding of different laws, facts and principles of natural sciences is pure science
Application of the knowledge of pure science for the welfare of human beings is applied science
Scopes of physics
Simple machines
Lever pulley trolley wheel and axel screw wedge, water lifting pump
Computer which work like human brain
Light
Heat
Sound
Electricity
Magnet
Scopes of chemistry
Scopes of biology
Theories of origin of life
Theory of Special Creation
This theory was proposed by Hebrew et al and strongly supported by Father Suarez. According to Bible, God created this universe, all animals and plants including ocear, mountain etc. The life was created during 4004 BC in six consecutive days. The heaven and earth were created on 1st day. Sky was separated from water on the 2nd day. On the 3rd day, the land and plants were created. On the 4th day, the Sun, Moon and Stars were created. Te 5th day, fish and fowl were created. Animals were created on 6th day. The first human was Adam created from inanimate matter the clay which was furnished with soul. Then it started breathing. The first woman was Eve who was created from one of his ribs.
All existing animals and plants were created by God. According to Hindu Mythology, Brahma( God of Creation) created different forms of life. The body of all living beings was made up of five elements( pancha maha bhut) like the earth(Prithvi), water(jala), fire(Teja), sky(Akash) and air(Bayu). After the death, all these elements will be returned to pancha maha bhuta.
This theory states that
1. The life was created by God or Creater
2. Formed all of a sudden, out of nothing
3. No interrelationship among living beings and
4. Have not undergone any change
The life is a mysterious force or vital spirit that set living things completely apart from non living and originated due to some supernatural event. It is accepted on basis of faith. One should believe in the existence of God. However, this theory can not be proved experimentally. So biologists do not believe in this theory.
Objections
Charles Darwin condemned special creation theory saying that earth has not always been inhabited by plants and animals as we know now. It means there is always a change. This theory lacks sound logic, scientifically sound evidence, it could not convince scientists.
Theory of Spontaneous generation or abiogenesis
Before the end of the Seventeenth century, both biologists and philosophers believed that non living things could arise from the non living(inanimate) substance spontaneously. This remained true for centuries in the past. This theory was proposed by Von Helmont(1577-1644). In China, even from earliest time, there was belief that aphid and other insects under the influence of heat and moisture, come into existence. In sacred books of India, there are indication of sudden emergence of different parasites, flies, beetles from sweat and manure. The Babylonian cuneiform text showed the worms and other creatures were formed form the mud of canals. In ancient Egypt, the conviction prevailed that layer of humus deposited by Nile river in its flood gave birth to living creatures like toads and frogs.
o Frogs, toads, snakes etc were believed to be developed from mud
o Parasites, beetles flies etc from sweat and manures
o Aphids and other insects arose under the influence of heat and moisture
o Fly maggots from flesh
o Young mice could arise from wheat grains and when these are kept in a dark room along with dirty clothes
Anaximenes (586-524 BC) proposed that air as sole cause of life.
Aristtotle (384-322BC proposed that worms, insects, fish, tape worm from excreta, crab, salamanders from earth can be developed.
Experiment of Von Helmont
Von Helmont kept dirty shirt and few grains of wheat in a cup board for 21 days. He observed mice developed from sweat and wheat. So, he proposed that both sexes of mice will be developed directly from non living things. He conducted this experiment in the support of spontaneous generation.
We find the repetition of these tales in the writings of ancient Greeks like Thales(624-547 BC), Empedocles(485-425 BC), Democritus (460-370 BC), Plato (427-347BC ) and Aristotle(384-322 BC).
William Harvey(1578-1627) despite the statement that all life come from egg was not able to tear himself from the concept that lower forms of life may aboriginate by spontaneous generation from non living precursors.
Theory of biogenesis
This theory states that life is originated not from inanimate substance but from the preexisting forms only.
Redi’s Classical Experiment
Italian Physician Sir Francisco Redi (1621-1697) demonstrated that maggots were not created from meat or fishes. In his classical experiment, he placed lumps of boiled meat in jars, some uncovered, some covered with muslin cloth and some with parchment paper. After few day, he observed fly maggots only in the uncovered jars.
The discovery of microbs by Van Leeuwenhoek (1632-1723) brought the question that microbs are so simple and could arise by Spontaneous Generation. This idea was authoritatively maintained by German philosopher Leibniz (1646-1716), French naturalist Buffon (1707-1788) and Englishman John Ne dham (1713-1781).
The decline and fall of the theory of Spontaneous Generation
An Italian scholar Abbe Spallanzani tested the theory of Spontaneous Generation. In 1765, he prepared flasks of meat broth which were boiled for several hours and then sealed. This broth remained clear for months and when seals were broken and broth tested, it was shown to be free of microbs.
Spallanzani’s experiment were neither conclusive nor satisfying to many of his contemporary scientist. They claimed that by boiling, he had driven out the vital force needed for Spontaneous generation. And also the sealed flask contained no oxygen.
The period of Louis Pasteur(1822-1895) : Pasteur devised several experiment means by which Spontaneous Generation of microbs was disproved. The simplest and most sophisticated one was with the use of a swan- neck flask. He prepared meat broth in this flask and boiled for several hours. He then left the flask unsealed. The flask was not sealed and there was free exchange of air with environment and system did not lack oxygen. Still the swan –neck remained free of microbial contamination for months because their swan neck were so shaped to trap the viable microbial particles and allow only air to enter the flask. After several months, he broke the neck of the flask and did not find the microbs. This simple experiment thus altogether disproved the concept of Spontaneous Generation. Thus it was proved that life could arise only from the pre existing life which is known as Biogenesis.
Cosmozoic theory
This theory was proposed by Richter 1865 AD and supported by Arrhenius 1908 AD. It states that life came on this earth from other planet in the form of seed or spore or panspermia. So, spore theory finding the suitable environment it grows into life. He could not explain mechanism by which panspermia survived adverse condition of high temp and lethal radiation of inter planatery space during migration.
Catastrophic theory
It was proposed by G Cuvier 1769-1832 and Orbigney 1802-1837. This theory states that there have been several creation each preceded by a catastrophy due to some major geological changes. Each catastrophy destroyed previous life completely and was followed by next advanced creation.
Steady state theory
This theory states that organisms have been unchangeable not only through out existence but also they have existed and continue to exist unchanging till eternity. Hutton says there is no beginning and end. This theory was supported by Richter and Arrhenius etc.
Modern or Natural or chemosynthetic theory of origin of life
This theory was proposed by Russian biochemist Alexander Ivanovich Oparin (1923) and supported by JBS Haldane (1928). This theory is popularly known as Oparin Haldane theory. This theory has been explained in detail in Oparin’s book “The Origin of life on the earth” published in 1936.
It states that primitive life originated in the water bodies on the primitive earth by chemical evolution through a series of chemical reaction about 4200 million years ago.
Steps
A. Origin of Earth (Biopoiesis)
The earth is supposed to be originated about 4.6 billion (4x109) years ago. The sphere was filled with cloud masses of dust particles called ylem. The rotation and gravity caused condensation and formed entire solar system. The earth when formed was very hot (4000 – 8000 oC ), like a ball of fire. Gradually cooled in next few million of years. They started condensing forming solids, liquids and gases. Heavy elements shank at the centre forming core. The lighter one (Aluminum, silicon, sodium, potassium ) formed the middle core of earth. Thus, lithosphere was formed. Lightest gases N2 H2 CO2 He etc including water vapor with dust particle rose above the land surface and turned finally into atmosphere.
B. Origin of life on earth
It is expected that life originated on earth nearly 3.7 billion years ago and involved following changes.
I. Chemogeny
Volcanic gases like H2 N2 CO2 H2O He underwent many changes (chemical evolution) which took place in following steps.
i. Formation of original gases
The original gases like NH3, CH4, HCN etc would have formed by interaction of volcanic gases when primitive earth cooled down from 100 oC. The formation of prime component was the start of life in primitive earth
N2 + 3H2 ……… 2NH3
C + 2H2 ……… CH4
2C + N2 + H2 ….. 2HCN
ii. Formation of key bio micro compounds
Simple key bio micro compounds like pentose sugar, glycerol. Fatty acids aminoacids, nitrogen bases( adenine, cytosine, thymine, Guanine etc would have formed by interaction of original gases( NH3 CH4 HCN ) when the temp further went down to about 50 to 60 oC Such reaction took place under the action of heat coming from energy radiation of Sun lightning, lava, radio active elements like radium, uranium of rocks etc.
6CH4 + H2O …………….. C6H12O6 + 12H2
CO2 + 2NH3 …………….. CO(NH2)2 + H20
CH4 + H2O + NH3 +HCN ……….. Nitrogen bases
CH4 saturated hydrocarbon reacted with water there by forming unsaturated hydrocarbon like acetylene, ethylene etc. From these, aldehydes, ketones, alcohol, acid were formed spontaneously, still more complex organic compounds like glucose, amino acid, fatty acids etc and purine and pyrimidine were formed as key bio micro compounds.
iii. Formation of complex bio macro compounds
Complex bio macro compounds like starch, protein, lipid, nucleic acid would have formed by polymerization of key simple bio micro compounds in the presence of water.
C6H12O6 + C6H12O6+ + C6H12O6 + … Polysaccharides
Fatty acids + glycerol ……………………. Lipid(fat)
Amino acids + amino acids + amino acids + ……..Protein
Complex bio macro compounds thus formed did not undergo oxidation because primitive earth was reducing, no free O2 and no microbes present.
iv. Formation of coacervates
When earth further cooled down, water vapour turned into rain, earth surface shrunk and formed depression where rain water filled up and turned into lakes, sea, as hydrosphere. Up lands turned into mountains. In sea, bio macro compounds when mixed with sea water formed thin hot soup called “broth”. To this Haldane 1992 called ‘pre biotic soup’.
Miller Urey experiment
Stanley Miller and Harold C Urey in 1953 performed series of experiments and tested Oparin and Haldane theory. They devised an apparatus that simulated the conditions of the surface of pre biological earth and analyzed the molecular forms that arose. The apparatus consisted of exposing water vapor to electric spark of 75,000 volts(to represent the lightning of thunder storms) in an ammonia, methane and hydrogen atmosphere of the early earth. After two weeks of treatment, Miller chromatographed the final solution and found many organic compounds including both carbohydrates and amino acids. Many of the compounds were important metabolic intermediates of present day organisms.
Since free oxygen destroys most of the intermediate products, the presence of intermediate products supported the Oparin and Haldane’s hypothesis of reducing atmosphere of primitive earth. Abiotic synthesis of molecules is possible only in reducing atmosphere and abundance of free oxygen (as in earth today) prevents the abiotic origin of life. So, life is originated from the earth’s inorganic atmosphere in the past but is no longer happens today.
Sunday, August 14, 2011
Thursday, March 24, 2011
for class XI
Human responsibility for the protection of earth
The earth provides habitat, shelter , food and water for all the animals and plants living on this earth. This earth provides very good environment so that living organisms are surviving and will survive in the future also. Among all the animals, man is on the top of the living beings. Yet, man can not think of his own survival without other animals and plants. The existence of life is interlinked. Plants can trap the solar energy and provide Oxygen needed for all the animals. There is transfer of energy from plants to animals and other animals which are carnivores. Man is dominating all the living organisms on this earth. As man is on the top dominating all the living organisms, it becomes responsibility of man to protect all the living organisms and this earth together.
The Zoological name of man is Homo sapiens. Genus Homo means wise. Man is the most intelligent creature of all living organisms on this earth. Man has utilized all the natural resources of the earth the most. Besides, man has utilized the renewable natural resources faster than that can be regenerated naturally. The various activities of man (Anthropogenic) has led to the destruction of naturally growing forests, polluted the water bodies as well the air and surrounding. The establishment of the various industries with their wastes degraded the environment and made less suitable for the living organisms. Also, because of unlimited need of man, industrialization and agriculture have left no space on earth. As man has contributed to the degradation of natural resources, it is the man’s responsibility to protect the earth.
Ways to protect the earth
• Afforestaion and reforestation - plantation of trees and take care of all these plants.
• Control of population of man
• Pollution control
• Conservation of wild life and forest
• Sustainable development not destroying nature
• Use of clean energy like solar energy, wind energy
• Keep in mind that this earth also belongs to all living beings
• Think that by protecting earth and nature, man is protecting himself
The earth provides habitat, shelter , food and water for all the animals and plants living on this earth. This earth provides very good environment so that living organisms are surviving and will survive in the future also. Among all the animals, man is on the top of the living beings. Yet, man can not think of his own survival without other animals and plants. The existence of life is interlinked. Plants can trap the solar energy and provide Oxygen needed for all the animals. There is transfer of energy from plants to animals and other animals which are carnivores. Man is dominating all the living organisms on this earth. As man is on the top dominating all the living organisms, it becomes responsibility of man to protect all the living organisms and this earth together.
The Zoological name of man is Homo sapiens. Genus Homo means wise. Man is the most intelligent creature of all living organisms on this earth. Man has utilized all the natural resources of the earth the most. Besides, man has utilized the renewable natural resources faster than that can be regenerated naturally. The various activities of man (Anthropogenic) has led to the destruction of naturally growing forests, polluted the water bodies as well the air and surrounding. The establishment of the various industries with their wastes degraded the environment and made less suitable for the living organisms. Also, because of unlimited need of man, industrialization and agriculture have left no space on earth. As man has contributed to the degradation of natural resources, it is the man’s responsibility to protect the earth.
Ways to protect the earth
• Afforestaion and reforestation - plantation of trees and take care of all these plants.
• Control of population of man
• Pollution control
• Conservation of wild life and forest
• Sustainable development not destroying nature
• Use of clean energy like solar energy, wind energy
• Keep in mind that this earth also belongs to all living beings
• Think that by protecting earth and nature, man is protecting himself
Monday, March 7, 2011
for class XII
Human ear
Ear is stato acoustic organ. It is responsible for sensations of equilibrium and hearing. It is sensitive to frequencies of sound waves and to change in relation with gravity. There are two ears and are situated one on either side of head.
Each ear consists of three main parts.
External ear
Middle ear
Internal ear
External ear -- it consists of pinna, auditory canal and tympanic membrane or ear drum. It is air filled cavity. It receives or collects sound waves and directs he sound waves to middle ear.
Pinnae-- these are flap of tissue supported by cartilages. These are found one on either side of head. these are immovable. Thee is presence of small opening that leads into auditory canal. It collects the sound waves and sends it to auditory canal.
Autitory canal -- it is also known as ear tube or external auditory meatus. It is lined by skin which has hairs for protection. Glands are preset to secret brown wax. If more and more wax is collected, it may cause deafness. It ends in eardrum.
Tympanic membrane-- it is also known as ear drum. It is thin sheet of tissue. it is delicate, membranous structure. It vibrates in response to the sound waves. It transmits sound waves to middle ear.
Middle ear - - it is also air filled cavity. It consist of three tiny bones called ear ossicles . thjey are malleus, incus and stapes, ear ossicles move forward and backward in resplonse to vibrations of ear drum.
Malllleus -- it is hammer shaped and articulate with incus on the other side.
Incus-- it is anvil like structure articulating with malleus on one side and stapes on other side.
Stapes -- it is stirrup like. Its foot plate or base is attached to oval window called fenestra ovalis or fenestra vestibule. These three ear ossicles are arranged in lever like action. They magnify and transfer the vibrations from ear drum to cochlea of inner ear through oval window.
Eustachian tube – it is a tube that leads from pharynx to middle ear. It helps in equalizing air pressure on both sides of ear drum. When air pressure is unequal, the ear drum becomes more stretched and can cause pain.
Inner ear -- it is fluid filled chamber it consists of complex system of canals and cavities. It basically consists of cochlea (associated with hearing) and vestibular apparatus( associated with balance)
Cochlea -- it is a highly coiled tube about 35 mm in length. It has got three canals inside, the vestibular canal, middle canal and tympanic canal. The reissner’s membrane separates the vestibular and middle canal. Similarly basilar membrane separates middle and tympanic canal. Both vestibular and tympanic canal are filled with fluid called perilymph. The vestibular canal is connected to oval window on the other side of which stapes is attached. The tympanic canal is connected to round window. The middle canal is filled with endolymph. There is basilar membrane on one side. The sensory hair cells rest on this basilar membrane. These cells are in contact with tectorial membrane above . the tectorial membrane, sensory hair cells and basilar membrane together form the organ of corti. The organ of corti can generate the sound impulse and send it to brain through auditory nerve.
Mechanism of hearing
As the sound waves enter the external ear, they pass through canal and strike the ear drum. The vibrations of ear drum are transmitted to three ear ossicles which magnify them 20 to 25 times. As stapes fits into the oval window, when it vibrates, the fluid perilymph in the vestibular canal vibrates. These vibrations cause the movement of the basilar membranes which in turn moves the sensory hair cells attached to it creating the nerve impulse. The sound waves transmitted to nerve impulse travel through auditory nerve to auditory cortex in brain. If the vibrations in perilymph are more than needed to stimulate the sensory hair cells, then they can be dissipated through round window into the middle ear and into the pharynx. The variations in the intensity and pitch are determined by the amplitude by which the basilar membrane vibrates and region of the organ of corti that gets stimulated.
Mechanism of balance
The vestibular apparatus of inner ear consist of utriculus, sacculus and semicircular canals. All of them are filled with endolymph. The three semicircular canals are at right angle to each other. Each one has a swelling at one end called ampulla. The semicircular canals open into utriculus where it is connected to the sacculus. The balance receptors are present in the utriculus, sacculus and the ampullae of the semicircular canals. These receptors contain the sensory hair cells which are very sensitive to the position of head with respect to gravity. The three semicircular canals are so arranged that the movement in any plane can be detected by these cells and generate impulse. The impulses are passed on to brain through the auditory nerves. Then we know that the body is not in balance and keep it in balance.
Eye
Eye is photoreceptor organ. Two eyes are situated at the front in the orbital fossae of skull. Eyes are very much important, so they are protected by eye brows and eye lids. Eyes can be moved within the orbit in different directions. The movement of eyes is due to six sets of muscles attached to outer surface of eye ball. They are superior, inferior , medial and lateral rectal muscles and superior and inferior oblique muscles. Eye lashes protect eyes from entering dust particles and germs.
There are presence of glands like meiobomian and lachrymal or tear gland. Meiobomian gland is found at upper inner corner of eye. It secretes oily secretion. This oil holds little tear for lubrication. Lachrymal glands are found at outer corner of eye. Lachrymal glands secrete watery fluid called tear. Tear is salty fluid which keeps conjunctiva moist. Tear is drained into nose through nasolacrimal duct at inner corner of conjunctiva.
Eyes are spherical structure. The diameter is about 2.5 cm. Eyes consist of tissues arranged in three concentric layers.
o Outer layer consists of sclerotic or sclera and cornea
o Middle layer consists of choroids, ciliary body and iris
o Inner layer consists of retina
Sclerotic layer -- it is made up of tough connective tissue. it is white in color and opaque. It forms about 5/6 part of eye ball. Most of its part lies at back. It provides surface for attachment of muscles. It maintains shape and protects inner part.
Cornea -- it is elevated part at the front. It is thin and transparent. It forms about 1/5 part of eye ball. It allows light to pass into eye. Due to curvature, it helps in focusing a real inverted image on retina.
Conjunctiva -- it is very much thin transparent membrane covering the cornea and sclera. It is having blood supply. If injured, it gives red color to the eye.
Choroids-- it is vascularised and pigmented layer. So it provides nourishment to retina. Due to pigmentation, it reduces the reflection of light inside eye.
Ciliary body – it is found at the junction of sclera and cornea. It is also vascularised. There are presence of ciliary muscles. These muscles change shape of lens. Contraction results in more spherical shape and relaxation results in flattened shape. From ciliary body, there arises suspensory ligaments. Suspensory ligaments hold lens in position.
Iris -- it is separated from cornea and forms muscular diaphragm just in front of lens. It is also vascularised. It gives color to eye like black, brown, blue etc.
Pupil -- iris is perforated and the opening is called pupil. The dilated muscle present in iris can control the size of pupil. It controls the amount of light entering the eye. In the bright light the size of pupil becomes smaller and in dim light it becomes larger.
Retina -- it consists of two sub layers, outer pigmented and inner photoreceptor layer. In the photoreceptor layer, there are two types of photosensitive cells, cones and rods. The cones are for discrimination of color hence gives sharp vision. The rods are for formation of image at dim light. Three types of cones are there. One type is stimulated by red end of spectrum, the second one by middle green region and third one by blue violet end. The normal color blind is inability to distinguish between red and green.
Fovea -- it is also known as yellow spot. It is slightly depressed area at middle part of retina. It contains only cones. It forms sharpest image.
Blind spot—at the back of eye, from where the optic nerve enters into the eye is called blind spot. It does not contain cones and rods. If image is formed at blind spot, it can not be seen. No image is formed here.
Lens – it is transparent, biconvex structure held in position by suspensory ligaments. It focuses light on the retina for image formation.
Aqueous chamber -- it is space behind cornea and in front of lens. It is filled with watery fluid called aqueous humour. It nourishes cornea and support lens by its pressure. Behind the lens is large space called vitreous chamber filled with jelly like space called vitreous humour. It supports lens and retina.
Working of eye -- light rays fall on cornea. The light rays pass through pupil, lens. The rays are converged by cornea, aqueous humour lens and vitreous humour. They focus the rays at retina. So a small inverted image of object is formed. The convexity of lens can be changed to bring a sharp focus on retina. The eyes are able to focus distant object as well as near by objects. It is known as accommodation. The eyes are suited for viewing distant objects. To see nearer objects, the lens becomes thicker by contraction of ciliary muscles.
Defects of eyes
Defects of eyes are due to curvature of cornea, change in curvature of lens, size of eye ball and opacity of lens etc.
Normal vision is called emmetropia
Myopia or near sightedness
Nearer objects can be seen clearly but objects at about the distance of 6 meters can not be seen clearly. It is due to large eye ball or high curvature of lens. The rays coming fro distant object are focused in front of retina. It can be corrected by biconcave lens.
Hypermetropia
In this distant objects can be seen but near objects are not seen clearly. It is either due to small eye ball, or low convexity of lens. The rays coming from near objects are focused beyond the retina. Use of biconvex lens can correct it.
Presbyopia
It is also long sightedness. It is developed after the age of 40. It is due to loss of flexibility of lens. It is corrected by use of convex lens.
Astigmatism
The vertical and horizontal bars can not be focused at the same time. It is due to uneven curvature of cornea. For correction, cylindrical lens is used.
Cataract
It is developed after about the age of 60. The lens becomes less transparent. Light rays can not pass and person losses ability to see. No treatment for this, the lens should be removed surgically. The artificial lens should be implanted or spectacles with convex lens should be used.
Glaucoma
If the aqueous humour is secreted more, the intra ocular pressure increases which can cause blindness. If it is detected in time it can be cured.
Night blindness
It is due to deficiency of vitamin A in diet. Vitamin A forms Rhodopsin. It is needed for working of rods in the retina.
Color blindness
It takes place due to absence of certain cone cells. The normal colorblindness is that in which red and green can not be differentiated.
Human reproductive system
The reproductive system in and are distinctly different both in structure and fuction. There are some common terms applied to both.
Primary sex organs or gonads
Testis in
Ovaries in
These organs under go number of changes during development and perform basic functions
1. produce gametes testis -sperms
ovaries -ova
2. as ductless glands secrete hormones
testis - testosterone
ovary - estrogen and progesterone
the development of both of these organs is under the control of gonadotropins FSH and LH from anterior pituitary gland
secondary sex organs
in male, prostate gland, seminal vesicle, vas deferens and penis etc
in female, fallopian tubes, uterus, vagina and mammary glands etc
These organs perform important functions but do not produce gametes. These are associated with primary sex organs. The development growth maintenance is under the control of sex hormones produced by ovaries and testis. Sex hormones responsible for sexual behavior and drives influence development of many other organs and tissues of body.
Accessory or external sex characters
They do not play any direct role in reproduction but are distinct and help to distinguish both sexes.
In male, low pitch voice and distribution of pattern of body hair
In female, high pitch voice and distribution pattern of body hair.
Male reproductive system
The male reproductive system consists of testis, epididymus, duct system and accessory glands.
Testis
These are paired gonads. They produce male gametes sperms and secrete male sex hormones testosterone. These are present or enclosed in a loose fold of skin called scrotum. They are found out side the abdominal cavity, where temp remains 2- 3 C below body temperature that is essential for sperm formation. Each testis is enclosed in a tough capsule known as tunica albugenia and testis consists of large no. of seminiferous tubules. In between the tubules there are specialized cells known as Leydig cells. Seminiferous tubules open into a space inside the testis called rete testis. From this space a no. of small, very fine tubules called vasa efferentia arise. These vasa efferentia fuse in the head of epididymus.
Epididymus
Single highly coiled tube about 5 meters long. Sperms formed in the seminiferous tubules pass through vasa efferentia and they are stored in the epididymus. Sperms get concentrated and maturity and mobility in epididymus. Epididymus leads into vas deferens.
Vas deferens
It is short straight tube. It ascends into abdominal cavity. It loops over the urinary bladder and opens into common urethra. Urethra passes through penis and opens at tip of penis.
Penis
It is made up of spongy muscular tissue. This tissue when filled with blood causes erection and enlargement of the organ. The tip of penis (glans) is highly sensitive. Sexual excitement can cause the erection of penis. Vessels are dilated to collect blood in spongy tissue. As tissue become distended, it compresses the vein so as to inhibit flow of blood out of tissue. With continued stimulation the penis and underlying bulb become hard and enlarged.
The penis consists of 3 columns of spongy tissue, 2 columns of corpora cavernosa above and 1 column of corpus spongiosum below. Corpus spongiosum includes the urethra. The tip of glans is slightly enlarge. It is covered by fold of skin called prepuce. The function of penis is to deposit semen in the genital tract of female.
Female reproductive system
Consists of ovary, oviducts, uterus, vagina, vulva and accessory glands.
Ovary -- paired structure, dark coloured and held in position by ligaments( mesovarium. Situated in abdominal cavity, one on either side of vertebral coloumn behind kidneys.
Each ovary is lined by germinal epithelium. The inner mass of fibrous connective tissue is called stroma. Stroma contains blood capillaries and nerve fibers and ovarian follicles etc. ovarian follicles develop from germinal epithelial cells. A marured follicle is called Graafian follicle. Outer membrane of Graafian follicle is membrane granulose. There is fluid filled cavity called antrum. In this cavity there lies ovum. The ovum is surrounded by Zona pellucida or zona radiata
The Graafian follicle finally ruptures to release mature egg into surrounding peritoneal cavity. It is picked up by fimbriated opening of fallopian tube. The follicle cells with blood clot forms corpus luteum.
The duct system-- consists of 2 fallopian tubes, uterus and vagina.
Fallopian tubes or oviducts. These ducts have a funnel shaped fimbriated opening to receive eggs as they mature. The ciliated funnel leads distally into a long narrow and convoluted tubule called fallopian tube. It has infundibulum which is fimbriated, ampulla, wide part where fertilization takes place, isthimus, narrow and straight part. Its walls are contractile and lined internally with ciliated epithelium. These cilia help egg to move towards uterus.
Uterus – 2, fallopian tube open into a thick walled muscular organ called uterus. The inner wall of uterus is called endometrium. Endometrium is richly supplied with blood vessels and glands. Upper dome shaped part is Fundus, broad above and narrow below is body, The lower tip of uterus is called cervix where there is opening internal os and opening below external os opens to vagina
Vagina -- it is a large fibromuscular chamber ( tube) that runs from uterus to outside. The fibro muscular chamber is lined by stratified epithelium. It opens outside by vulva.
Females have separate urethral and vaginal openings unlike males. At vaginal orifice, partially covered membrane in vergin called hymen. Epithelial cells produce glycogen, anaerobic oxidation of which produce lactic acid for protection from infection.
Vulva is guarded by two folds of tissue labia majora and labia minora.
Clitoris present analogous to penis in male.
Glands
bertholin’s gland one pair,similar to cowper’s gland
The secretion of bertholin’s gland is viscid fluid that makes the vaginal passage slippery needed at the time of intercourse.
Mammary gland one pair, located at chest region. The development of mammary gland is influenced by female sex hormone. The production of milk is due to another hormone called prolactin. The release of milk is due to oxytocin hormone soon after the birth of child.
Process of fertilization
During the sexual intercourse, ejaculation takes place in which semen is deposited in the vagina of female called orgasm. Due to the contraction of vaginal passage, sperms move up into the uterus and fallopian tube. If they find the ovum, the wall of ovum dissolved by the sperm lysine of large no. of sperms. Then one sperm pierces the ovum and fuses with the ovum. It results into the formation of zygote. It is implanted into the wall of uterus known as endometrium.
Menstrual cycle
Cyclic changes occur with periodicity of 28 days. Starts about the age of 9- 10, continues to about the age of 50. No cycle during pregnancy. Starts again after few months of child birth. Stoppage of cycle at old age menopause, which shows incapability of woman of reproduction.
Menstrual phase
o lasts for about first 3- 5 days.
o Breaking down of endometrium , epithelium lining, connective tissue blood vessels slashed off and discharge as menstruation.
o Estrogen and progesterone very low.
o Weeping of uterus
Proliferative phase
o it remains for 5th to 14th day, it lasts for about 9 or 10 days till ovulation.
o Begins with repair of damaged endometrium
o Induced by FSH, also follicular phase – one egg matures in each cycle.
o Primary oocyte undergoes first meiotic div, and changed into sec oocyte forms Graafian follicle.
o Estrogen secreted by Graafian follicle, its level increases, becomes maximum about 3 days before ovulation.
o Estrogen causes thickening of endometrium and develop blood vessels in it.
o Uterine movement increase due to contraction of uterine muscles.
Ovulation phase
o One matured egg is released from the Graafian follicle on the 14th day.
o Corpus luteum is formed by ruptured follicle also called yellow body.
Secretory phase
o Lasts for 12 -14 days, from 15th to 28th day.
o Induced by LH also called Luteal phase.
o Corpus luteum releases Progesterone, causes further thickenings of endometrium for implantation.
o Under its influence, tubular glands secrete mucus, uterus becomes fluid filled and glandular.
o Uterine movement decrease considerably.
o Progesterone inhibits further maturation of any follicle or ovulation from ovary.
o If ovum is not fertilized, corpus luteum degenerates, level of both estrogen and progesterone decrease at about 28th day.
Ear is stato acoustic organ. It is responsible for sensations of equilibrium and hearing. It is sensitive to frequencies of sound waves and to change in relation with gravity. There are two ears and are situated one on either side of head.
Each ear consists of three main parts.
External ear
Middle ear
Internal ear
External ear -- it consists of pinna, auditory canal and tympanic membrane or ear drum. It is air filled cavity. It receives or collects sound waves and directs he sound waves to middle ear.
Pinnae-- these are flap of tissue supported by cartilages. These are found one on either side of head. these are immovable. Thee is presence of small opening that leads into auditory canal. It collects the sound waves and sends it to auditory canal.
Autitory canal -- it is also known as ear tube or external auditory meatus. It is lined by skin which has hairs for protection. Glands are preset to secret brown wax. If more and more wax is collected, it may cause deafness. It ends in eardrum.
Tympanic membrane-- it is also known as ear drum. It is thin sheet of tissue. it is delicate, membranous structure. It vibrates in response to the sound waves. It transmits sound waves to middle ear.
Middle ear - - it is also air filled cavity. It consist of three tiny bones called ear ossicles . thjey are malleus, incus and stapes, ear ossicles move forward and backward in resplonse to vibrations of ear drum.
Malllleus -- it is hammer shaped and articulate with incus on the other side.
Incus-- it is anvil like structure articulating with malleus on one side and stapes on other side.
Stapes -- it is stirrup like. Its foot plate or base is attached to oval window called fenestra ovalis or fenestra vestibule. These three ear ossicles are arranged in lever like action. They magnify and transfer the vibrations from ear drum to cochlea of inner ear through oval window.
Eustachian tube – it is a tube that leads from pharynx to middle ear. It helps in equalizing air pressure on both sides of ear drum. When air pressure is unequal, the ear drum becomes more stretched and can cause pain.
Inner ear -- it is fluid filled chamber it consists of complex system of canals and cavities. It basically consists of cochlea (associated with hearing) and vestibular apparatus( associated with balance)
Cochlea -- it is a highly coiled tube about 35 mm in length. It has got three canals inside, the vestibular canal, middle canal and tympanic canal. The reissner’s membrane separates the vestibular and middle canal. Similarly basilar membrane separates middle and tympanic canal. Both vestibular and tympanic canal are filled with fluid called perilymph. The vestibular canal is connected to oval window on the other side of which stapes is attached. The tympanic canal is connected to round window. The middle canal is filled with endolymph. There is basilar membrane on one side. The sensory hair cells rest on this basilar membrane. These cells are in contact with tectorial membrane above . the tectorial membrane, sensory hair cells and basilar membrane together form the organ of corti. The organ of corti can generate the sound impulse and send it to brain through auditory nerve.
Mechanism of hearing
As the sound waves enter the external ear, they pass through canal and strike the ear drum. The vibrations of ear drum are transmitted to three ear ossicles which magnify them 20 to 25 times. As stapes fits into the oval window, when it vibrates, the fluid perilymph in the vestibular canal vibrates. These vibrations cause the movement of the basilar membranes which in turn moves the sensory hair cells attached to it creating the nerve impulse. The sound waves transmitted to nerve impulse travel through auditory nerve to auditory cortex in brain. If the vibrations in perilymph are more than needed to stimulate the sensory hair cells, then they can be dissipated through round window into the middle ear and into the pharynx. The variations in the intensity and pitch are determined by the amplitude by which the basilar membrane vibrates and region of the organ of corti that gets stimulated.
Mechanism of balance
The vestibular apparatus of inner ear consist of utriculus, sacculus and semicircular canals. All of them are filled with endolymph. The three semicircular canals are at right angle to each other. Each one has a swelling at one end called ampulla. The semicircular canals open into utriculus where it is connected to the sacculus. The balance receptors are present in the utriculus, sacculus and the ampullae of the semicircular canals. These receptors contain the sensory hair cells which are very sensitive to the position of head with respect to gravity. The three semicircular canals are so arranged that the movement in any plane can be detected by these cells and generate impulse. The impulses are passed on to brain through the auditory nerves. Then we know that the body is not in balance and keep it in balance.
Eye
Eye is photoreceptor organ. Two eyes are situated at the front in the orbital fossae of skull. Eyes are very much important, so they are protected by eye brows and eye lids. Eyes can be moved within the orbit in different directions. The movement of eyes is due to six sets of muscles attached to outer surface of eye ball. They are superior, inferior , medial and lateral rectal muscles and superior and inferior oblique muscles. Eye lashes protect eyes from entering dust particles and germs.
There are presence of glands like meiobomian and lachrymal or tear gland. Meiobomian gland is found at upper inner corner of eye. It secretes oily secretion. This oil holds little tear for lubrication. Lachrymal glands are found at outer corner of eye. Lachrymal glands secrete watery fluid called tear. Tear is salty fluid which keeps conjunctiva moist. Tear is drained into nose through nasolacrimal duct at inner corner of conjunctiva.
Eyes are spherical structure. The diameter is about 2.5 cm. Eyes consist of tissues arranged in three concentric layers.
o Outer layer consists of sclerotic or sclera and cornea
o Middle layer consists of choroids, ciliary body and iris
o Inner layer consists of retina
Sclerotic layer -- it is made up of tough connective tissue. it is white in color and opaque. It forms about 5/6 part of eye ball. Most of its part lies at back. It provides surface for attachment of muscles. It maintains shape and protects inner part.
Cornea -- it is elevated part at the front. It is thin and transparent. It forms about 1/5 part of eye ball. It allows light to pass into eye. Due to curvature, it helps in focusing a real inverted image on retina.
Conjunctiva -- it is very much thin transparent membrane covering the cornea and sclera. It is having blood supply. If injured, it gives red color to the eye.
Choroids-- it is vascularised and pigmented layer. So it provides nourishment to retina. Due to pigmentation, it reduces the reflection of light inside eye.
Ciliary body – it is found at the junction of sclera and cornea. It is also vascularised. There are presence of ciliary muscles. These muscles change shape of lens. Contraction results in more spherical shape and relaxation results in flattened shape. From ciliary body, there arises suspensory ligaments. Suspensory ligaments hold lens in position.
Iris -- it is separated from cornea and forms muscular diaphragm just in front of lens. It is also vascularised. It gives color to eye like black, brown, blue etc.
Pupil -- iris is perforated and the opening is called pupil. The dilated muscle present in iris can control the size of pupil. It controls the amount of light entering the eye. In the bright light the size of pupil becomes smaller and in dim light it becomes larger.
Retina -- it consists of two sub layers, outer pigmented and inner photoreceptor layer. In the photoreceptor layer, there are two types of photosensitive cells, cones and rods. The cones are for discrimination of color hence gives sharp vision. The rods are for formation of image at dim light. Three types of cones are there. One type is stimulated by red end of spectrum, the second one by middle green region and third one by blue violet end. The normal color blind is inability to distinguish between red and green.
Fovea -- it is also known as yellow spot. It is slightly depressed area at middle part of retina. It contains only cones. It forms sharpest image.
Blind spot—at the back of eye, from where the optic nerve enters into the eye is called blind spot. It does not contain cones and rods. If image is formed at blind spot, it can not be seen. No image is formed here.
Lens – it is transparent, biconvex structure held in position by suspensory ligaments. It focuses light on the retina for image formation.
Aqueous chamber -- it is space behind cornea and in front of lens. It is filled with watery fluid called aqueous humour. It nourishes cornea and support lens by its pressure. Behind the lens is large space called vitreous chamber filled with jelly like space called vitreous humour. It supports lens and retina.
Working of eye -- light rays fall on cornea. The light rays pass through pupil, lens. The rays are converged by cornea, aqueous humour lens and vitreous humour. They focus the rays at retina. So a small inverted image of object is formed. The convexity of lens can be changed to bring a sharp focus on retina. The eyes are able to focus distant object as well as near by objects. It is known as accommodation. The eyes are suited for viewing distant objects. To see nearer objects, the lens becomes thicker by contraction of ciliary muscles.
Defects of eyes
Defects of eyes are due to curvature of cornea, change in curvature of lens, size of eye ball and opacity of lens etc.
Normal vision is called emmetropia
Myopia or near sightedness
Nearer objects can be seen clearly but objects at about the distance of 6 meters can not be seen clearly. It is due to large eye ball or high curvature of lens. The rays coming fro distant object are focused in front of retina. It can be corrected by biconcave lens.
Hypermetropia
In this distant objects can be seen but near objects are not seen clearly. It is either due to small eye ball, or low convexity of lens. The rays coming from near objects are focused beyond the retina. Use of biconvex lens can correct it.
Presbyopia
It is also long sightedness. It is developed after the age of 40. It is due to loss of flexibility of lens. It is corrected by use of convex lens.
Astigmatism
The vertical and horizontal bars can not be focused at the same time. It is due to uneven curvature of cornea. For correction, cylindrical lens is used.
Cataract
It is developed after about the age of 60. The lens becomes less transparent. Light rays can not pass and person losses ability to see. No treatment for this, the lens should be removed surgically. The artificial lens should be implanted or spectacles with convex lens should be used.
Glaucoma
If the aqueous humour is secreted more, the intra ocular pressure increases which can cause blindness. If it is detected in time it can be cured.
Night blindness
It is due to deficiency of vitamin A in diet. Vitamin A forms Rhodopsin. It is needed for working of rods in the retina.
Color blindness
It takes place due to absence of certain cone cells. The normal colorblindness is that in which red and green can not be differentiated.
Human reproductive system
The reproductive system in and are distinctly different both in structure and fuction. There are some common terms applied to both.
Primary sex organs or gonads
Testis in
Ovaries in
These organs under go number of changes during development and perform basic functions
1. produce gametes testis -sperms
ovaries -ova
2. as ductless glands secrete hormones
testis - testosterone
ovary - estrogen and progesterone
the development of both of these organs is under the control of gonadotropins FSH and LH from anterior pituitary gland
secondary sex organs
in male, prostate gland, seminal vesicle, vas deferens and penis etc
in female, fallopian tubes, uterus, vagina and mammary glands etc
These organs perform important functions but do not produce gametes. These are associated with primary sex organs. The development growth maintenance is under the control of sex hormones produced by ovaries and testis. Sex hormones responsible for sexual behavior and drives influence development of many other organs and tissues of body.
Accessory or external sex characters
They do not play any direct role in reproduction but are distinct and help to distinguish both sexes.
In male, low pitch voice and distribution of pattern of body hair
In female, high pitch voice and distribution pattern of body hair.
Male reproductive system
The male reproductive system consists of testis, epididymus, duct system and accessory glands.
Testis
These are paired gonads. They produce male gametes sperms and secrete male sex hormones testosterone. These are present or enclosed in a loose fold of skin called scrotum. They are found out side the abdominal cavity, where temp remains 2- 3 C below body temperature that is essential for sperm formation. Each testis is enclosed in a tough capsule known as tunica albugenia and testis consists of large no. of seminiferous tubules. In between the tubules there are specialized cells known as Leydig cells. Seminiferous tubules open into a space inside the testis called rete testis. From this space a no. of small, very fine tubules called vasa efferentia arise. These vasa efferentia fuse in the head of epididymus.
Epididymus
Single highly coiled tube about 5 meters long. Sperms formed in the seminiferous tubules pass through vasa efferentia and they are stored in the epididymus. Sperms get concentrated and maturity and mobility in epididymus. Epididymus leads into vas deferens.
Vas deferens
It is short straight tube. It ascends into abdominal cavity. It loops over the urinary bladder and opens into common urethra. Urethra passes through penis and opens at tip of penis.
Penis
It is made up of spongy muscular tissue. This tissue when filled with blood causes erection and enlargement of the organ. The tip of penis (glans) is highly sensitive. Sexual excitement can cause the erection of penis. Vessels are dilated to collect blood in spongy tissue. As tissue become distended, it compresses the vein so as to inhibit flow of blood out of tissue. With continued stimulation the penis and underlying bulb become hard and enlarged.
The penis consists of 3 columns of spongy tissue, 2 columns of corpora cavernosa above and 1 column of corpus spongiosum below. Corpus spongiosum includes the urethra. The tip of glans is slightly enlarge. It is covered by fold of skin called prepuce. The function of penis is to deposit semen in the genital tract of female.
Female reproductive system
Consists of ovary, oviducts, uterus, vagina, vulva and accessory glands.
Ovary -- paired structure, dark coloured and held in position by ligaments( mesovarium. Situated in abdominal cavity, one on either side of vertebral coloumn behind kidneys.
Each ovary is lined by germinal epithelium. The inner mass of fibrous connective tissue is called stroma. Stroma contains blood capillaries and nerve fibers and ovarian follicles etc. ovarian follicles develop from germinal epithelial cells. A marured follicle is called Graafian follicle. Outer membrane of Graafian follicle is membrane granulose. There is fluid filled cavity called antrum. In this cavity there lies ovum. The ovum is surrounded by Zona pellucida or zona radiata
The Graafian follicle finally ruptures to release mature egg into surrounding peritoneal cavity. It is picked up by fimbriated opening of fallopian tube. The follicle cells with blood clot forms corpus luteum.
The duct system-- consists of 2 fallopian tubes, uterus and vagina.
Fallopian tubes or oviducts. These ducts have a funnel shaped fimbriated opening to receive eggs as they mature. The ciliated funnel leads distally into a long narrow and convoluted tubule called fallopian tube. It has infundibulum which is fimbriated, ampulla, wide part where fertilization takes place, isthimus, narrow and straight part. Its walls are contractile and lined internally with ciliated epithelium. These cilia help egg to move towards uterus.
Uterus – 2, fallopian tube open into a thick walled muscular organ called uterus. The inner wall of uterus is called endometrium. Endometrium is richly supplied with blood vessels and glands. Upper dome shaped part is Fundus, broad above and narrow below is body, The lower tip of uterus is called cervix where there is opening internal os and opening below external os opens to vagina
Vagina -- it is a large fibromuscular chamber ( tube) that runs from uterus to outside. The fibro muscular chamber is lined by stratified epithelium. It opens outside by vulva.
Females have separate urethral and vaginal openings unlike males. At vaginal orifice, partially covered membrane in vergin called hymen. Epithelial cells produce glycogen, anaerobic oxidation of which produce lactic acid for protection from infection.
Vulva is guarded by two folds of tissue labia majora and labia minora.
Clitoris present analogous to penis in male.
Glands
bertholin’s gland one pair,similar to cowper’s gland
The secretion of bertholin’s gland is viscid fluid that makes the vaginal passage slippery needed at the time of intercourse.
Mammary gland one pair, located at chest region. The development of mammary gland is influenced by female sex hormone. The production of milk is due to another hormone called prolactin. The release of milk is due to oxytocin hormone soon after the birth of child.
Process of fertilization
During the sexual intercourse, ejaculation takes place in which semen is deposited in the vagina of female called orgasm. Due to the contraction of vaginal passage, sperms move up into the uterus and fallopian tube. If they find the ovum, the wall of ovum dissolved by the sperm lysine of large no. of sperms. Then one sperm pierces the ovum and fuses with the ovum. It results into the formation of zygote. It is implanted into the wall of uterus known as endometrium.
Menstrual cycle
Cyclic changes occur with periodicity of 28 days. Starts about the age of 9- 10, continues to about the age of 50. No cycle during pregnancy. Starts again after few months of child birth. Stoppage of cycle at old age menopause, which shows incapability of woman of reproduction.
Menstrual phase
o lasts for about first 3- 5 days.
o Breaking down of endometrium , epithelium lining, connective tissue blood vessels slashed off and discharge as menstruation.
o Estrogen and progesterone very low.
o Weeping of uterus
Proliferative phase
o it remains for 5th to 14th day, it lasts for about 9 or 10 days till ovulation.
o Begins with repair of damaged endometrium
o Induced by FSH, also follicular phase – one egg matures in each cycle.
o Primary oocyte undergoes first meiotic div, and changed into sec oocyte forms Graafian follicle.
o Estrogen secreted by Graafian follicle, its level increases, becomes maximum about 3 days before ovulation.
o Estrogen causes thickening of endometrium and develop blood vessels in it.
o Uterine movement increase due to contraction of uterine muscles.
Ovulation phase
o One matured egg is released from the Graafian follicle on the 14th day.
o Corpus luteum is formed by ruptured follicle also called yellow body.
Secretory phase
o Lasts for 12 -14 days, from 15th to 28th day.
o Induced by LH also called Luteal phase.
o Corpus luteum releases Progesterone, causes further thickenings of endometrium for implantation.
o Under its influence, tubular glands secrete mucus, uterus becomes fluid filled and glandular.
o Uterine movement decrease considerably.
o Progesterone inhibits further maturation of any follicle or ovulation from ovary.
o If ovum is not fertilized, corpus luteum degenerates, level of both estrogen and progesterone decrease at about 28th day.
Sunday, March 6, 2011
for touchstone 2011
The Living World
Raghubar Shrestha
Associate Prof. of Zoology,
HoD, Biology Department
Plants and animals have been surviving on this earth for time immemorial. They had different forms, shapes and structures. They are all, the part of the living world. They are all living a life and one question is often asked. What is life? It’s very difficult to answer. However, biologists have come across the suitable answer to this question. Life can generate energy within its body, use energy for carrying out various activities. Living things move about except the developed plants. They grow in size, take food, respire, excrete, undergo reproduction, and respond to the external stimuli. The use of energy within their body is in various forms like heat energy to keep their body warm. Certain fire worms can produce light, certain fishes can produce electric current. Most of the vertebrates can produce sound energy. On the other hands, non living things cannot use energy. Still it cannot be said that, non living things do not have energy. We have the example from the ancient period. Just by striking two stones, the ancestors of man produced fire. The stone at the top of the mountain has the potential energy. Similarly , the water in the pond has potential energy. Any time, the stone and water can go into movement and potential energy is changed into kinetic energy. The non living things move on and on until a force is applied to stop them.
When living things move, they can stop by themselves. They have internal force which can stop them from moving ahead. The life can be compared with some sort of movement. To remain idle is nearly death. The young children move here and there the whole day. More the movements, there is more life, many years to live. As we grow, movements slow down and down. At the very old age, the movement is very less and it means the death is very much near.
Before we born, or say, before we start our life, the sperms swim around the relatively stationary ovum. The sperms are always in movement. It is due to movement that the sperms find ovum and one of the sperms quickly fertilizes it. After the fertilization, the zygote is formed in all sexually reproducing organisms. This is the beginning of the life. Not only living things, the stars, the planets, the moons in the space are all the time in movement. In the smallest particle, the atom, we can see the electrons are in movements. The electrons are moving around the nucleus in their own orbit. The water, the air what are not in movement?
Inside the body of living organisms, the heart is pumping blood twenty-four hours a day. The circulation of blood is associated with life. Once the circulation of blood is ceased, there is no life. Similarly, the breathing movements are continuous process. At different parts of body, muscles are present. They can contract and expand. Actually, these muscles help in the movements of fluid and waste materials from one part to another part of the body. Because of such movements, urine and undigested wastes etc can be discharged from the body. Similarly, the sperms and ova in male and female are carried down the duct system for fertilization. The muscles contract and expand to secrete the juices and enzymes in the body so that foods can be digested properly. During the proliferative phase in the menstrual cycle in females, there is contraction in the wall of uterus which can help in the ascending movement of the sperms to find the ova. In the working of nervous system, the impulses are carried at the faster rate along the nerve fiber to the brain and various information from brain to the target organ. All these are one or other form of movements.
Again, not only the movements in side body, the muscles help in the movement of parts of the body or whole body, which is the external movement. The movement or locomotion of these animals are needed to find their food, to protect themselves from various types of enemies, to move to suitable environment as well as to find the sexual partner and to find the safer place to rear their young ones. They cannot remain moving here and there. In wild animals, they need certain area to move about for their reproduction. Still, many fishes and birds migrate for months and to a longer distances. Such migration in these animals are of great importance to get all the available facilities for proliferation of their race.
Besides, in the birds and mammals, there are movements used for communication among the members of various animals. In the Primates of Class Mammalia like monkeys, apes and man, facial expressions are seen. They can actively show the expression of happiness or sorrow by facial expression. For this, there are number of muscles in their face. By the movements of these muscle, the facial expression is possible. The eye movements are so important in communication that one can read the eyes to know many things. The blinking of eye is necessary for proper functioning of eye. Inside the ear of animal, there are three ear ossicles namely malleus, incus and stapes. They are heavily built and joined like in the lever. By their movements, magnify the sound waves and pass to the internal ear. Such movements help in the process of hearing. The movements in the parts of our body can help a great in the non verbal communication.
Though, we cannot see the locomotion in higher plants like the trees, bushes and herbs, there are the movements of water as well as of food they prepare in their leaves from one part to another part of their body. Transpiration is a continuous process, in which plants absorb water from the soil and excess water is lost from the leaves in the form of vapor. Most of the plants usually move towards the source of light. They need the light for manufacturing their food. Photosynthesis is the process in which plants absorb CO2 from atmosphere and water from soil and then in the presence of light chlorophyll can manufacture food.
In case of plants, the movement or transfer of pollen grains into the stigma of gynoeceium in the same flower or to the other flower in the another plant, is assisted by air, water, honey bees or other animals. There will be no fertilization and growth in plants without such movements.
In the non living things also, there are movements. The electric current moves from higher potential to lower potential. The air is always moving from higher pressure to lower pressure. The moving air takes the clouds from one part to another part. There is the water cycle. The water evaporates from the sea, clouds taken to the mountains by air and causes rainfall. The water in the brooks, rivers etc are always running which can support various lives at different parts of the world. Not only these, there are Carbon cycle, Nitrogen cycle, Phosphorus cycle etc. all these chemicals are moving from one part to another part helping all the living animals and plants in their survival.
Speed of some of the living and non living objects
Light 299792.458 Kilometer/second
Concord jet 594.44 meter/second
Sound 340.29 meter/second at sea level
Nerve impulse 120 meter/second
Fast train 111.1 meter/second
Cheetah 31.1 meter/second
Usual speed of running being 22.2 meter/second
Motor cycle 11.1 meter/second
A brisk walk of man 1.1 meter/second
A Rocket needs a velocity of 11.2 Kilometer/second to leave the earth if projected directly at perpendicular to the earth surface. From the above table, it seems that light travels the fastest of all, far more than that of Rocket. But still, the human mind can travel faster than the light.
The Sun, the various planets like Earth, Jupiter and Saturn etc are moving in their own orbit to balance the gravitational force. As the Earth goes round the Sun, there are the days and nights and different seasons throughout the year. The plants and animals have various activities according to the day length and different seasons like winter, spring, summer and autumn etc. They become inactive during winter and summer and active during spring, rainy season and autumn.
From all the things above, it is obvious that the life and movements are so much associated that there will be no life without movements in living as well as non living things. The movement is a kind of kinetic energy. All the living organism live using one or another form of energy and the movement or locomotion is of great importance in the act of living in this world.
Raghubar Shrestha
Associate Prof. of Zoology,
HoD, Biology Department
Plants and animals have been surviving on this earth for time immemorial. They had different forms, shapes and structures. They are all, the part of the living world. They are all living a life and one question is often asked. What is life? It’s very difficult to answer. However, biologists have come across the suitable answer to this question. Life can generate energy within its body, use energy for carrying out various activities. Living things move about except the developed plants. They grow in size, take food, respire, excrete, undergo reproduction, and respond to the external stimuli. The use of energy within their body is in various forms like heat energy to keep their body warm. Certain fire worms can produce light, certain fishes can produce electric current. Most of the vertebrates can produce sound energy. On the other hands, non living things cannot use energy. Still it cannot be said that, non living things do not have energy. We have the example from the ancient period. Just by striking two stones, the ancestors of man produced fire. The stone at the top of the mountain has the potential energy. Similarly , the water in the pond has potential energy. Any time, the stone and water can go into movement and potential energy is changed into kinetic energy. The non living things move on and on until a force is applied to stop them.
When living things move, they can stop by themselves. They have internal force which can stop them from moving ahead. The life can be compared with some sort of movement. To remain idle is nearly death. The young children move here and there the whole day. More the movements, there is more life, many years to live. As we grow, movements slow down and down. At the very old age, the movement is very less and it means the death is very much near.
Before we born, or say, before we start our life, the sperms swim around the relatively stationary ovum. The sperms are always in movement. It is due to movement that the sperms find ovum and one of the sperms quickly fertilizes it. After the fertilization, the zygote is formed in all sexually reproducing organisms. This is the beginning of the life. Not only living things, the stars, the planets, the moons in the space are all the time in movement. In the smallest particle, the atom, we can see the electrons are in movements. The electrons are moving around the nucleus in their own orbit. The water, the air what are not in movement?
Inside the body of living organisms, the heart is pumping blood twenty-four hours a day. The circulation of blood is associated with life. Once the circulation of blood is ceased, there is no life. Similarly, the breathing movements are continuous process. At different parts of body, muscles are present. They can contract and expand. Actually, these muscles help in the movements of fluid and waste materials from one part to another part of the body. Because of such movements, urine and undigested wastes etc can be discharged from the body. Similarly, the sperms and ova in male and female are carried down the duct system for fertilization. The muscles contract and expand to secrete the juices and enzymes in the body so that foods can be digested properly. During the proliferative phase in the menstrual cycle in females, there is contraction in the wall of uterus which can help in the ascending movement of the sperms to find the ova. In the working of nervous system, the impulses are carried at the faster rate along the nerve fiber to the brain and various information from brain to the target organ. All these are one or other form of movements.
Again, not only the movements in side body, the muscles help in the movement of parts of the body or whole body, which is the external movement. The movement or locomotion of these animals are needed to find their food, to protect themselves from various types of enemies, to move to suitable environment as well as to find the sexual partner and to find the safer place to rear their young ones. They cannot remain moving here and there. In wild animals, they need certain area to move about for their reproduction. Still, many fishes and birds migrate for months and to a longer distances. Such migration in these animals are of great importance to get all the available facilities for proliferation of their race.
Besides, in the birds and mammals, there are movements used for communication among the members of various animals. In the Primates of Class Mammalia like monkeys, apes and man, facial expressions are seen. They can actively show the expression of happiness or sorrow by facial expression. For this, there are number of muscles in their face. By the movements of these muscle, the facial expression is possible. The eye movements are so important in communication that one can read the eyes to know many things. The blinking of eye is necessary for proper functioning of eye. Inside the ear of animal, there are three ear ossicles namely malleus, incus and stapes. They are heavily built and joined like in the lever. By their movements, magnify the sound waves and pass to the internal ear. Such movements help in the process of hearing. The movements in the parts of our body can help a great in the non verbal communication.
Though, we cannot see the locomotion in higher plants like the trees, bushes and herbs, there are the movements of water as well as of food they prepare in their leaves from one part to another part of their body. Transpiration is a continuous process, in which plants absorb water from the soil and excess water is lost from the leaves in the form of vapor. Most of the plants usually move towards the source of light. They need the light for manufacturing their food. Photosynthesis is the process in which plants absorb CO2 from atmosphere and water from soil and then in the presence of light chlorophyll can manufacture food.
In case of plants, the movement or transfer of pollen grains into the stigma of gynoeceium in the same flower or to the other flower in the another plant, is assisted by air, water, honey bees or other animals. There will be no fertilization and growth in plants without such movements.
In the non living things also, there are movements. The electric current moves from higher potential to lower potential. The air is always moving from higher pressure to lower pressure. The moving air takes the clouds from one part to another part. There is the water cycle. The water evaporates from the sea, clouds taken to the mountains by air and causes rainfall. The water in the brooks, rivers etc are always running which can support various lives at different parts of the world. Not only these, there are Carbon cycle, Nitrogen cycle, Phosphorus cycle etc. all these chemicals are moving from one part to another part helping all the living animals and plants in their survival.
Speed of some of the living and non living objects
Light 299792.458 Kilometer/second
Concord jet 594.44 meter/second
Sound 340.29 meter/second at sea level
Nerve impulse 120 meter/second
Fast train 111.1 meter/second
Cheetah 31.1 meter/second
Usual speed of running being 22.2 meter/second
Motor cycle 11.1 meter/second
A brisk walk of man 1.1 meter/second
A Rocket needs a velocity of 11.2 Kilometer/second to leave the earth if projected directly at perpendicular to the earth surface. From the above table, it seems that light travels the fastest of all, far more than that of Rocket. But still, the human mind can travel faster than the light.
The Sun, the various planets like Earth, Jupiter and Saturn etc are moving in their own orbit to balance the gravitational force. As the Earth goes round the Sun, there are the days and nights and different seasons throughout the year. The plants and animals have various activities according to the day length and different seasons like winter, spring, summer and autumn etc. They become inactive during winter and summer and active during spring, rainy season and autumn.
From all the things above, it is obvious that the life and movements are so much associated that there will be no life without movements in living as well as non living things. The movement is a kind of kinetic energy. All the living organism live using one or another form of energy and the movement or locomotion is of great importance in the act of living in this world.
Tuesday, February 22, 2011
for class XII
Nervous system of man
As complexity in animals increases, the coordination of different parts of body among themselves and with the external environment becomes necessary. Human body is complex and highly developed. In human beings and other higher animals, the nervous system and endocrine system not only control and coordinate various cellular activities but also help animal to respond to stimulus. The nervous system is comparatively faster and localized in action.
Functions
• It receives changes in external environment by receptors and after interpreting and analyzing, sends the appropriate massages to effectors. The sensory organ like tongue, nose eye ears skin helps to receive stimulus from environment.
• It conducts information and transmits massages to various parts of body.
• It stimulates and inhibits the activities of various muscle and glands according to the kind of information received.
• It receives and coordinates the activities of various visceral organs in the body.
• By coordinating different activities it helps to maintain steady state of body.
Types
a. Central nervous system CNS which includes brain and spinal cord
b. Peripheral nervous system PNS which includes cranial nervous and spinal nerves.
c. Autonomic nervous system which includes nerve cells, ganglia etc
The central nervous system
The brain and spinal cord both are supported and protected by skeleton. The brain is protected by cranium and spinal cord is protected by vertebral column. Brain and spinal cord are covered by three membranes together known as meninges.
1. outer membrane duramater
2. middle membrane arachnoid
3. inner membrane piamater
Duramater is tough and made up of fibrous tissue. It is attached to skull. The middle membrane is soft and thin. Piamater is delicate and vascularised.
Subarachnoid space – it is space between arachnoid and piamater. An extracellular fluid called cerebrospinal fluid CSF is present in subarachnoid space, ventricles of brain and central canal of spinal cord. The CSF is slightly alkaline fluid. It is kept in circulation by beating of ciliated cells(ependymal) lining ventricles and central canal. It is secreted by anterior and posterior choroid plexus.
Functions of CSF
• It allows exchange of respiratory gases, nutrients and wastes between it and nervous tissue. It is both nutritive and excretory in function.
• It protects the CNS against mechanical shock and injury. It acts as cushion.
• It maintains the constant pressure inside cranium in spite of fluctuations in volume and pressure of blood.
Both brain and spinal cord show two distinct regions called Grey matter and White matter.
Differences between gray and white matter
Gray matter White matter
Gray in color White in color due to presence of fatty myelin sheath around nerve fiber.
Consist of cell bodies, dendrite and synapses of neuron. Consists of nerve fibers axon arising from or to nerve cell present in gray matter.
Contains numerous intermediate neurons Mainly consists of axons of neurons connecting various body of brain and links brain to spinal cord.
In brain, gray matter is found outside and white matter inside. The spinal cord, white matter forms outer layer and gray matter forms central core.
Human Brain
It is highly specialized delicate organ of the human body. It is present in a bony case called cranium. Cranium protects brain form external injuries. The brain of adult weighs about 1350 grams. It is mainly composed of soft nervous tissue. The cranial capacity of human is about 1450 cc.
The human brain can be divided into 3 parts
Fore brain (Prosencephalon)
Mid brain (Mesencepahlon)
Hind brain(Rhombencephalon)
Fore brain has 3 parts – Cerebrum, Thalamus and Hypothalamus
Cerebrum - it is largest part and divisible into right and left Cerebral Hemisphere (CH). Two CH are joined by broad curved and thick band of nerve fiber called Corpus Callosum. Each hemisphere has frontal lobe, parietal lobe and temporal lobe and occipital lobe. Outer layer is called cerebral cortex. It is made up of gray matter and has numerous fold like convolutions. The ridges of convolutions are known as gyri and depressions in between are known as sulci. These greatly increase surface area.
The cerebral cortex has different areas like motor area (movement), sensory area (heat and cold pain touch light pressure) auditory area (hearing), visual area (seeing), olfactory area (taste and smell), speech area etc.
Functions
1. Main center that governs all mental activities like intelligence, memory, reason, will, feelings, emotions etc.
2. Seat of consciousness, interpreter of sensations, origin of voluntary acts.
3. Also acts as control on many reflex acts that originates involuntary like weeping, laughing etc.
Thalamus
It lies between Cerebrum and mid brain. It consists of 2 rounded masses of gray matter.
It is found at the center of cerebrum.
Functions
1. Serves as relay center for sensory and motor impulses from spinal cord and brain stem to various parts of Cerebrum.
2. Regulates emotions and perceptions of heat cold pain etc.
Hypothalamus
It is present beneath Thalamus. It consists of gray matter scattered in white matter.
Functions
1. Controls internal mechanism or autonomic nervous system.
2. associated with temp regulation, water balance, hunger, blood pressure etc
3. In association with pituitary gland, secretes neurohormones.
Mid brain
It connects fore brain with hind brain. It possesses 2 pairs of round elevations called Corpora quadrigemina. The gray matter is found to be scattered in white matter. It is covered by CH. It controls the eye movements and auditory response. The floor of mid brain has thick crura cerebri. It contains bundles of fibers coming from hind brain and spinal cord passing forward.
Hind brain
It consists of Cerebellum on dorsal side and brain stem (pons and medulla) on ventral side.
Cerebellum - it is found at the back of head. It consists of 2 cerebellar hemispheres just like CH. It gives appearance of two halves of a large walnut. It is large reflex center for coordination of muscular body movements and maintained of posture or equilibrium. Cerebellar hemispheres are not convoluted but traversed by furrows. The central part is known as vermis.
Functions
• Coordinate muscular body movement, equilibrium and control posture.
• Control reflex action of skeletal muscle activities.
Pons varolii- it lies above medulla. It acts as bridge to connect two halves of cerebellum. It coordinates muscle movements on two sides.
Medulla oblongata – it is posterior most part of brain. It continues behind into spinal cord. Various ascending and descending tracts cross over from right to left and left to right. Any damage to one of its side causes paralyses on the opposite side of body.
Functions
• It carries nerve tracts connecting spinal cord to brain. All communications between brain and spinal cord pass through it.
• Center for vital activities
• Contains cardiac, respiratory and vasomotor center that control complex activities like heart action, respiration, coughing and sneezing etc.
Ventricles of brain.
These are cavities within the bran. They are 4 in number.
Right and left lateral ventricles lie within the CH. These communicate with the third ventricle (ventricle of Thalamus) by foramen of Monro. The third ventricle communicates with the fourth ventricle (ventricle of Medulla) by cerebral aqueduct or iter. The fourth ventricle is lozenge shaped and continues behind as central canal of spinal cord.
Spinal cord
It is tubular or cylindrical structure extending from Medulla Oblongata. It is situated in the neural canal of vertebral column. It is covered by all three membranes. The cerebrospinal fluid is present in the central canal and in between membranes. The white matter is found outside and Grey matter is found inside. The grey matter is in the the H shaped of butterfly shaped form. The dorsal and ventral horns come out from the Grey matter. In the middle, there is central canal. It is filled with cerebrospinal fluid and continuous with the ventricles of brain.
Peripheral nervous system
It consists of two types of nerves. Cranial nerves are arising from brain and spinal nerves arising from spinal cords.
A nerve is composed of many nerve fibers enclosed in a connective tissue sheath. Nerve fiber is long axon of a neuron . it could be myelinated or non myelinated.
Types of nerve fiber
Depending upon the direction of nerve impulse carried by nerve fiber, they are classified into
• Afferent nerve fiber which conduct impulses from peripheral tissue or organ (receptors) to CNS. It is also called sensory neuron
• Efferent nerve fiber which conduct nerve impulse from CNS to peripheral tissue or organs or effectors. It is also called motor neurons
Cranial nerves
There are 12 pairs of cranial nerves. They arise from different parts of Brain. These nerves innervate different tissue of organ to carry out different functions. They are sensory or motor or mixed in function.
Name of nerve nature Tissue innervated function
1. olfactory sensory Olfactory mucosa in nose smell
2. optic sensory Retina vision
3. oculomotor motor Eye muscle Eye movement
4. trochlear motor ,, ,, ,, ,,
5. trigeminal mixed Skin, teeth, mucosal membrane of mouth Sensation of head and face
6. abducens motor Eye muscle Eye movement
7. facial mixed Taste buds, salivary gland, muscle of face and neck Facial expression, saliva secretion
8. auditory sensory Internal ear Equilibrium, hearing
9. glossopharyngeal mixed Pharynx tongue Taste, sensation, swallowing
10. vagus mixed Pharynx, oesophagus, trachea, viscera Visceral reflex
11. spinal accessory motor Thoracic and abdominal viscera Visceral reflex, shoulder movement
12. hypoglossal motor Muscle of tongue movement
Sensory -- 1st , 2nd , 8th
Motor -- 3rd , 4th , 6th , 11th , 12th
Mixed -- 5th , 7th , 9th , 10th
Spinal nerves
There are 31 pairs of spinal nerves in man. They arise from the spinal cord. They innervate different parts of body. They are all mixed in nature.
Cervical nerves = 8 pairs
Thoracic nerves = 12 pairs
Lumbar nerves = 5 pairs
Sacral nerves = 5 pairs
Coccygeal nerves = 1 pair
C 8 Th 12 L 5 S 5 Co 1
Autonomic nervous system
It consists of nerves that control and coordinate activities of visceral organ like heart, lung, kidney, arteries, vein etc. It controls the functioning of visceral organ so, it is known as visceral nervous system.
Properties
• Basically motor system – they carry impulses from CNS to effectors
• Involuntary in action, controls activities like heart beat, peristaltic movement
• Consists of preganglionic fiber, autonomic ganglion and post ganglionic fiber etc
• Preganglionic nerve fiber is made up of motor neuron emerge from CNS and enter into autonomic ganglion
• Autonomic ganglion is swollen bulbous structure in which preganglionic fiber terminate and synapse with cell bodies of post ganglionic fiber
• Axon from cell bodies emerge out and pass to organ concerned
Sympathetic nervous system
They emerge from thoraco lumbar region. At the end of post ganglionic fiber, nor adrenaline is secrected. So, they are called adrenergic in function.
• Can stimulate many organ
• Prepare body for emergency
• Increase heart beat
• Dilate pupil
• Rise arterial BP
Parasympathetic nervous system
They emerge from cranio sacral out flow. At the end of post ganglionic fiber, acetyl choline is produced. So they are called cholinergic in nature.
Properties
• Associated with daily normal activities
• Stimulation of gastric, pancreatic secretion
• Gastro intestinal movement
• It has inhibitory effect on organ
• Brings about relaxation, comfort
• Prevent over working of organ
• Restore normalcy of organ
Transmission of nerve impulse
Prosser defined the nerve impulse as the sum of mechanical, chemical and electrical disturbances created by a stimuli in a neuron. The most accepted mechanism f nerve impulse conduction is Ionic theory prepared by Hodgekin and Huxley. This theory states that nerve impulse is an electrochemical event governed by differential permeability of neurilemma to Na + and K+ which in turn is regulated by the electrical field. The transmission of nerve impulse takes place always in one direction. It is very rapid process. About 1000 impulses can be carried in one second time along the same nerve fiber. It consists of following steps.
• Polarisation (resting potential) -- the extracellular fluid has high concentration of Na+ and low concentration of K+ . Out side the membrane, there are 10 times more Na+ and inside there are 25 times more K+ . The neurilemma is less permeable to Na+ and more permeable to K+ . the neurilemma shows – 70 to – 90 milli volts (mV). Out side the membrane there are + charges and inside there are – charges.
• Depolarization (action potential)-- when it receives stimuli, the permeability changes. It becomes more permeable to Na+ and less permeable to K+ . Now Na+ ions rush inside and K+ ions out side. Due to rapid inflow of Na+ the potential increases to 0 and then to +45 to +50 mV. Inside the membrane the + charges are developed and out side, - charges are developed. The newly developed potential difference is called action potential.
• Repolarisation -- after peak of action potential called spike potential, permeability to Na+ decreases and permeability to K+ increases. Na + ions are pumped out and K+ ions are taken in. This is called Sodium Potassium pump or simply Sodium pump. Sodium pump is a process of expelling out Sodium ions and drawing in Potassium ions against the concentration and electrochemical gradient. Out side the membrane there develop the + charges and inside, there develop the – charges. It is called repolarisation. The axon is made ready to receive another impulse.
Transmission of nerve impulse along the medullated nerve fiber
The medullary sheath is not permeable to both Na + and K+ ions. So, the ionic exchange occur only at the nodes of Ranvier. The action potential is conducted from node to node in a jumping manner. Nerve impulse is conducted faster ( about 20 times) in myelinated nerve fiber. It is called salutatory conduction.
Conduction of nerve impulse through synapse
In a synaptic cleft, the impulse is always carried from axon to dendrite. It is assisted by neurotransmitter like acetyl choline. It is purely a chemical event. Calcium ions help in this process.
As complexity in animals increases, the coordination of different parts of body among themselves and with the external environment becomes necessary. Human body is complex and highly developed. In human beings and other higher animals, the nervous system and endocrine system not only control and coordinate various cellular activities but also help animal to respond to stimulus. The nervous system is comparatively faster and localized in action.
Functions
• It receives changes in external environment by receptors and after interpreting and analyzing, sends the appropriate massages to effectors. The sensory organ like tongue, nose eye ears skin helps to receive stimulus from environment.
• It conducts information and transmits massages to various parts of body.
• It stimulates and inhibits the activities of various muscle and glands according to the kind of information received.
• It receives and coordinates the activities of various visceral organs in the body.
• By coordinating different activities it helps to maintain steady state of body.
Types
a. Central nervous system CNS which includes brain and spinal cord
b. Peripheral nervous system PNS which includes cranial nervous and spinal nerves.
c. Autonomic nervous system which includes nerve cells, ganglia etc
The central nervous system
The brain and spinal cord both are supported and protected by skeleton. The brain is protected by cranium and spinal cord is protected by vertebral column. Brain and spinal cord are covered by three membranes together known as meninges.
1. outer membrane duramater
2. middle membrane arachnoid
3. inner membrane piamater
Duramater is tough and made up of fibrous tissue. It is attached to skull. The middle membrane is soft and thin. Piamater is delicate and vascularised.
Subarachnoid space – it is space between arachnoid and piamater. An extracellular fluid called cerebrospinal fluid CSF is present in subarachnoid space, ventricles of brain and central canal of spinal cord. The CSF is slightly alkaline fluid. It is kept in circulation by beating of ciliated cells(ependymal) lining ventricles and central canal. It is secreted by anterior and posterior choroid plexus.
Functions of CSF
• It allows exchange of respiratory gases, nutrients and wastes between it and nervous tissue. It is both nutritive and excretory in function.
• It protects the CNS against mechanical shock and injury. It acts as cushion.
• It maintains the constant pressure inside cranium in spite of fluctuations in volume and pressure of blood.
Both brain and spinal cord show two distinct regions called Grey matter and White matter.
Differences between gray and white matter
Gray matter White matter
Gray in color White in color due to presence of fatty myelin sheath around nerve fiber.
Consist of cell bodies, dendrite and synapses of neuron. Consists of nerve fibers axon arising from or to nerve cell present in gray matter.
Contains numerous intermediate neurons Mainly consists of axons of neurons connecting various body of brain and links brain to spinal cord.
In brain, gray matter is found outside and white matter inside. The spinal cord, white matter forms outer layer and gray matter forms central core.
Human Brain
It is highly specialized delicate organ of the human body. It is present in a bony case called cranium. Cranium protects brain form external injuries. The brain of adult weighs about 1350 grams. It is mainly composed of soft nervous tissue. The cranial capacity of human is about 1450 cc.
The human brain can be divided into 3 parts
Fore brain (Prosencephalon)
Mid brain (Mesencepahlon)
Hind brain(Rhombencephalon)
Fore brain has 3 parts – Cerebrum, Thalamus and Hypothalamus
Cerebrum - it is largest part and divisible into right and left Cerebral Hemisphere (CH). Two CH are joined by broad curved and thick band of nerve fiber called Corpus Callosum. Each hemisphere has frontal lobe, parietal lobe and temporal lobe and occipital lobe. Outer layer is called cerebral cortex. It is made up of gray matter and has numerous fold like convolutions. The ridges of convolutions are known as gyri and depressions in between are known as sulci. These greatly increase surface area.
The cerebral cortex has different areas like motor area (movement), sensory area (heat and cold pain touch light pressure) auditory area (hearing), visual area (seeing), olfactory area (taste and smell), speech area etc.
Functions
1. Main center that governs all mental activities like intelligence, memory, reason, will, feelings, emotions etc.
2. Seat of consciousness, interpreter of sensations, origin of voluntary acts.
3. Also acts as control on many reflex acts that originates involuntary like weeping, laughing etc.
Thalamus
It lies between Cerebrum and mid brain. It consists of 2 rounded masses of gray matter.
It is found at the center of cerebrum.
Functions
1. Serves as relay center for sensory and motor impulses from spinal cord and brain stem to various parts of Cerebrum.
2. Regulates emotions and perceptions of heat cold pain etc.
Hypothalamus
It is present beneath Thalamus. It consists of gray matter scattered in white matter.
Functions
1. Controls internal mechanism or autonomic nervous system.
2. associated with temp regulation, water balance, hunger, blood pressure etc
3. In association with pituitary gland, secretes neurohormones.
Mid brain
It connects fore brain with hind brain. It possesses 2 pairs of round elevations called Corpora quadrigemina. The gray matter is found to be scattered in white matter. It is covered by CH. It controls the eye movements and auditory response. The floor of mid brain has thick crura cerebri. It contains bundles of fibers coming from hind brain and spinal cord passing forward.
Hind brain
It consists of Cerebellum on dorsal side and brain stem (pons and medulla) on ventral side.
Cerebellum - it is found at the back of head. It consists of 2 cerebellar hemispheres just like CH. It gives appearance of two halves of a large walnut. It is large reflex center for coordination of muscular body movements and maintained of posture or equilibrium. Cerebellar hemispheres are not convoluted but traversed by furrows. The central part is known as vermis.
Functions
• Coordinate muscular body movement, equilibrium and control posture.
• Control reflex action of skeletal muscle activities.
Pons varolii- it lies above medulla. It acts as bridge to connect two halves of cerebellum. It coordinates muscle movements on two sides.
Medulla oblongata – it is posterior most part of brain. It continues behind into spinal cord. Various ascending and descending tracts cross over from right to left and left to right. Any damage to one of its side causes paralyses on the opposite side of body.
Functions
• It carries nerve tracts connecting spinal cord to brain. All communications between brain and spinal cord pass through it.
• Center for vital activities
• Contains cardiac, respiratory and vasomotor center that control complex activities like heart action, respiration, coughing and sneezing etc.
Ventricles of brain.
These are cavities within the bran. They are 4 in number.
Right and left lateral ventricles lie within the CH. These communicate with the third ventricle (ventricle of Thalamus) by foramen of Monro. The third ventricle communicates with the fourth ventricle (ventricle of Medulla) by cerebral aqueduct or iter. The fourth ventricle is lozenge shaped and continues behind as central canal of spinal cord.
Spinal cord
It is tubular or cylindrical structure extending from Medulla Oblongata. It is situated in the neural canal of vertebral column. It is covered by all three membranes. The cerebrospinal fluid is present in the central canal and in between membranes. The white matter is found outside and Grey matter is found inside. The grey matter is in the the H shaped of butterfly shaped form. The dorsal and ventral horns come out from the Grey matter. In the middle, there is central canal. It is filled with cerebrospinal fluid and continuous with the ventricles of brain.
Peripheral nervous system
It consists of two types of nerves. Cranial nerves are arising from brain and spinal nerves arising from spinal cords.
A nerve is composed of many nerve fibers enclosed in a connective tissue sheath. Nerve fiber is long axon of a neuron . it could be myelinated or non myelinated.
Types of nerve fiber
Depending upon the direction of nerve impulse carried by nerve fiber, they are classified into
• Afferent nerve fiber which conduct impulses from peripheral tissue or organ (receptors) to CNS. It is also called sensory neuron
• Efferent nerve fiber which conduct nerve impulse from CNS to peripheral tissue or organs or effectors. It is also called motor neurons
Cranial nerves
There are 12 pairs of cranial nerves. They arise from different parts of Brain. These nerves innervate different tissue of organ to carry out different functions. They are sensory or motor or mixed in function.
Name of nerve nature Tissue innervated function
1. olfactory sensory Olfactory mucosa in nose smell
2. optic sensory Retina vision
3. oculomotor motor Eye muscle Eye movement
4. trochlear motor ,, ,, ,, ,,
5. trigeminal mixed Skin, teeth, mucosal membrane of mouth Sensation of head and face
6. abducens motor Eye muscle Eye movement
7. facial mixed Taste buds, salivary gland, muscle of face and neck Facial expression, saliva secretion
8. auditory sensory Internal ear Equilibrium, hearing
9. glossopharyngeal mixed Pharynx tongue Taste, sensation, swallowing
10. vagus mixed Pharynx, oesophagus, trachea, viscera Visceral reflex
11. spinal accessory motor Thoracic and abdominal viscera Visceral reflex, shoulder movement
12. hypoglossal motor Muscle of tongue movement
Sensory -- 1st , 2nd , 8th
Motor -- 3rd , 4th , 6th , 11th , 12th
Mixed -- 5th , 7th , 9th , 10th
Spinal nerves
There are 31 pairs of spinal nerves in man. They arise from the spinal cord. They innervate different parts of body. They are all mixed in nature.
Cervical nerves = 8 pairs
Thoracic nerves = 12 pairs
Lumbar nerves = 5 pairs
Sacral nerves = 5 pairs
Coccygeal nerves = 1 pair
C 8 Th 12 L 5 S 5 Co 1
Autonomic nervous system
It consists of nerves that control and coordinate activities of visceral organ like heart, lung, kidney, arteries, vein etc. It controls the functioning of visceral organ so, it is known as visceral nervous system.
Properties
• Basically motor system – they carry impulses from CNS to effectors
• Involuntary in action, controls activities like heart beat, peristaltic movement
• Consists of preganglionic fiber, autonomic ganglion and post ganglionic fiber etc
• Preganglionic nerve fiber is made up of motor neuron emerge from CNS and enter into autonomic ganglion
• Autonomic ganglion is swollen bulbous structure in which preganglionic fiber terminate and synapse with cell bodies of post ganglionic fiber
• Axon from cell bodies emerge out and pass to organ concerned
Sympathetic nervous system
They emerge from thoraco lumbar region. At the end of post ganglionic fiber, nor adrenaline is secrected. So, they are called adrenergic in function.
• Can stimulate many organ
• Prepare body for emergency
• Increase heart beat
• Dilate pupil
• Rise arterial BP
Parasympathetic nervous system
They emerge from cranio sacral out flow. At the end of post ganglionic fiber, acetyl choline is produced. So they are called cholinergic in nature.
Properties
• Associated with daily normal activities
• Stimulation of gastric, pancreatic secretion
• Gastro intestinal movement
• It has inhibitory effect on organ
• Brings about relaxation, comfort
• Prevent over working of organ
• Restore normalcy of organ
Transmission of nerve impulse
Prosser defined the nerve impulse as the sum of mechanical, chemical and electrical disturbances created by a stimuli in a neuron. The most accepted mechanism f nerve impulse conduction is Ionic theory prepared by Hodgekin and Huxley. This theory states that nerve impulse is an electrochemical event governed by differential permeability of neurilemma to Na + and K+ which in turn is regulated by the electrical field. The transmission of nerve impulse takes place always in one direction. It is very rapid process. About 1000 impulses can be carried in one second time along the same nerve fiber. It consists of following steps.
• Polarisation (resting potential) -- the extracellular fluid has high concentration of Na+ and low concentration of K+ . Out side the membrane, there are 10 times more Na+ and inside there are 25 times more K+ . The neurilemma is less permeable to Na+ and more permeable to K+ . the neurilemma shows – 70 to – 90 milli volts (mV). Out side the membrane there are + charges and inside there are – charges.
• Depolarization (action potential)-- when it receives stimuli, the permeability changes. It becomes more permeable to Na+ and less permeable to K+ . Now Na+ ions rush inside and K+ ions out side. Due to rapid inflow of Na+ the potential increases to 0 and then to +45 to +50 mV. Inside the membrane the + charges are developed and out side, - charges are developed. The newly developed potential difference is called action potential.
• Repolarisation -- after peak of action potential called spike potential, permeability to Na+ decreases and permeability to K+ increases. Na + ions are pumped out and K+ ions are taken in. This is called Sodium Potassium pump or simply Sodium pump. Sodium pump is a process of expelling out Sodium ions and drawing in Potassium ions against the concentration and electrochemical gradient. Out side the membrane there develop the + charges and inside, there develop the – charges. It is called repolarisation. The axon is made ready to receive another impulse.
Transmission of nerve impulse along the medullated nerve fiber
The medullary sheath is not permeable to both Na + and K+ ions. So, the ionic exchange occur only at the nodes of Ranvier. The action potential is conducted from node to node in a jumping manner. Nerve impulse is conducted faster ( about 20 times) in myelinated nerve fiber. It is called salutatory conduction.
Conduction of nerve impulse through synapse
In a synaptic cleft, the impulse is always carried from axon to dendrite. It is assisted by neurotransmitter like acetyl choline. It is purely a chemical event. Calcium ions help in this process.
for class XI model questions 2067 Biology
Zoology class XI model questions set 1
1. Give very short answers of the followings (any seven) 1x7=7
1.1. Classify liver fluke.
1.2. What is adaptational feature of apes .
1.3. List the classes of the phylum Porifera.
1.4. What is sinus venosus ?
1.5. How is the biological science related to physics ?
1.6. What is natural selection ?
1.7. Differentiate between anadromous migration and catadromous migration in fishes .
1.8. Write about the premordial atmosphere of the earth .
1.9. Define homologous organ with example .
1.10. Give scientific name of any two endangered mammal.
2. Give short answers of the followings (any five ) 3x5=15
2.1. What is extinction ?what are the causes of extinction?
2.2. Draw well labeled diagram of alimentary canal of frog.
2.3. Describe in brief the female reproductory organ of female earth worm.
2.4. Discuss the gamogony phase of life cycle of plasmodium vivax.
2.5. Explain the biochemical origin of life.
2.6. Explain the asexual reproduction of paramecium .
2.7. Explain the renal portal system found in frog .
3. What is reproduction ?Describe male reproductive organ of frog
with well label diagram . [7.5]
or
Give an account of conjugation in Paramecium caudatum and discuss its significance.
4.Define evolution .Explain the evolution of man from the pre ape man . [8]
Botany class XI model questions set 1
1. Give very short answers of the followings (any seven) 1x7=7
1.1. Differentiate between primary and secondary succession ?
1.2. Differentiate between primary and secondary succession.
1.3. Define binomial nomenclature .
1.4. What part of moss have diploid cells ?
1.5. Why are the blue green algae blue green in color ?
1.6. Define alternation of generation.
1.7. Define syngenesious stamen .
1.8. Name the chemical components of DNA.
1.9. Name the storage found in green and brown algae .
1.10. What do you mean by tetradynamous stamens ?
2. Give short answers of the followings (any five ) 3x5=15
2.1. Describe and structure and function of amino acids .
2.2. Discuss the changes that occur during metaphase of Mitosis.
2.3. Explain food chain with examples.
2.4. Explain about the structure and function of mitochondria .
2.5. Give beneficial aspects of Lichen.
2.6. What are the methods of forest conservation?
2.7. Draw a labelled diagram of mitotic anaphase and also mention its characteristic.
3. Give the distinguishing character of Solanaceae with its floral formula and floral diagram. Write the scientific name of sunflower , radish, maize and gram. [7.5]
OR
Discuss the vegetative structure and life cycle of mushroom .
4. Define bio geo chemical cycle . Describe nitrogen cycle in nature [8]
Zoology class XI model questions set 2
1. Give very short answers of the followings (any seven) 1x7=7
1.1. Define coacervate.
1.2. Give the function of seminal vesicles of earth worm .
1.3. Define homologous organ with example .
1.4. Name the various forms of locomotory organ found in aquatic animals .
1.5. Name the excretory organ found in Platyhelminthes and Annelids.
1.6. Define Neo Darwinism.
1.7. Define ornithology.
1.8. What was archaeopteryx ?
1.9. What is the functions of akinetes?
1.10. What is reflex action ?
2. Give short answers of the followings (any five ) 3x5=15
2.1. List the Volant adaptational characters of birds.
2.2. Give the significance of archaeopteryx in the study of evolution .
2.3. Explain the relation of biology with other science .
2.4. How exconjugants are formed during conjugation of paramecium ?
2.5. Explain the histological structure of liver of frog .
2.6. "Cro-Magnon is immediate ancestor of modern man " justify.
2.7. Explain the hepatic portal system found in frog .
3. Give an account of the structure of digestive tract of Pheretima. [7.5]
OR
Describe the structure of heart of frog with necessary diagram
4. Write an Essay on Darwinism. [8]
Botany class XI model questions set 2
1. Give very short answers of the followings (any seven) 1x7=7
1.1. Define the terms phycology and mycology.
1.2. Why yeast placed in fungi?
1.3. What is cell theory ?
1.4. Name two chemical components in the structure of virus.
1.5. In which food chain pyramid of number is inverted?
1.6. Name two economically important fungi.
1.7. State what spiklet inflorescence is.
1.8. Name four green house gasses .
1.9. Define the term coenocytic hypha.
1.10. What is acid rain ?
2. Give short answers of the followings (any five ) 3x5=15
2.1. Differentiate between mitotic and meiotic cell division.
2.2. Describe and structure and function of amino acids .
2.3. What is pesticides? What are the hazards caused by pesticides?
2.4. List the characteristics of gymnosperm .
2.5. Write briefly about the structure and function of nucleus .
2.6. Draw diagrammatic life cycle of Funaria . No description is needed .
2.7. Discuss the consequence of ozone layer depletion .
3. Give the distinguishing character of solanaceae with its floral formula and floral diagram. Write the scientific name of sunflower , radish, maize and gram[7.5]
Or
Discuss the vegetative structure and life cycle of mushroom .
4. Define bio geo chemical cycle . Describe nitrogen cycle in nature [8]
Zoology class XI model questions set 3
1. Give very short answers of the followings (any seven) 1x7=7
1.1. Give the scientific name of tapeworm and wall lizard.
1.2. Discuss the role of variation in organic evolution .
1.3. How do insects differ from Arachnida?
1.4. Define fossil.
1.5. What are early primates resemble to ?
1.6. Give two example of vestigial organ.
1.7. What is reflex arc?
1.8. What is the function of choanoderm in Porifera?
1.9. Who suggested that monkeys, apes and man have a common ancestor ?
1.10. Name the muscles that controls the setae of earthworm .
2. Give short answers of the followings (any five ) 3x5=15
2.1. Explain arboreal adaptation among reptiles.
2.2. Give an account on Australopithecus.
2.3. Represent diagrammatically the process of conjugation in paramecium .
2.4. Write in brief the erythrocytic cycle of Plasmodium.
2.5. Describe the experiment of Urey miller for the origin of life .
2.6. Differentiate between chondrichthys and oesteichtys fish .
2.7. Give the adaptational modifications found in scansorial animals .
3. Describe the reproductive organ of earthworm. [7.5]
Or
Describe the internal structure of heart in frog and give its working mechanism.
4. Write an Essay on Lamarckism. Write down the demerits of this theory and about the Neo Lamarckism. [8]
Botany class XI model questions set 3
1. Give very short answers of the followings (any seven) 1x7=7
1.1. What is the function of heterocyst?
1.2. Name two edible mushroom available in market .
1.3. Why is Spirogyra placed in algae?
1.4. Name two type recemose inflorescence you have studied.
1.5. Name the chemical components of RNA.
1.6. Name the storage found in green and brown algae .
1.7. What do you mean by tetradynamous stamens ?
1.8. Mention any two points of differences between primary and secondary mycelium.
1.9. Name the major components of virus .
1.10. Define the term nucleotide.
2. Give short answers of the followings (any five ) 3x5=15
2.1. Discuss the economic importance of fungi.
2.2. Give the structure and function of Golgi complex.
2.3. Differentiate between metaphase I and metaphase II of meiosis.
2.4. State the economic importance of the family solanaceae.
2.5. Draw diagrammatic life cycle of spirogyra. (no description)
2.6. Discuss the consequences of acid rain .
2.7. Explain the structure and functions of mitochondria.
3. What is altenation of generation ?Explain it with suitable diagram in a Marchantia. [7.5]
OR
Explain the characters of the family Papilionaceae in semitechnical term
with floral diagram and floral formula .Discuss any two major importance
of this family .
4. What is energy flow .Explain how it takes place in terrestrial ecosystem. [8]
Zoology class XI model questions set 4
1. Give very short answers of the followings (any seven) 1x7=7
1.1. Give scientific names of any two endangered mammals of Nepal.
1.2. Define Osteology.
1.3. Which technique is used to know the age of fossils ?
1.4. Give the functions of Typhlosole in Earth worm.
1.5. Write Scientific names of frog and star fish.
1.6. What do you mean by the word Arthropoda?
1.7. What is adaptation?
1.8. What is catadromous migration?
1.9. What is serological test?
1.10. What is torsion ? Give one example of animal which shows torsion .
2. Give short answers of the followings (any five ) 3x5=15
2.1. Discuss about the Cro magnon man.
2.2. Give the characteristic feature of class Aves.
2.3. Draw a neat and labeled diagram of Paramecium.
2.4. Give the functions of skin of earthworm.
2.5. How does cocoon formation takes place in earthworm?
2.6. Give a brief description of the T.S. of the testis of frog with neat labeled diagram.
2.7. Enumerate the characters of Annelida .
3. Give an account of life cycle of Plasmodium in man . [7.5]
OR
Discuss the reproductive system of Frog.
4. What is organic evolution ?Trace out evolution of man starting from Ramapethicus . [8]
Botany class XI model questions set 4
1. Give very short answers of the followings (any seven) 1x7=7
1.1. Define net primary productivity.
1.2. What is trophic level.
1.3. What do you mean by succession?
1.4. Why is lysosomes called as suicidal bag ?
1.5. Write any two consequence of acid rain.
1.6. Mention the chemical components of virus.
1.7. Write the meaning of syngenesis.
1.8. What is the function of pyrenoid ?
1.9. What is nucleotides ?
1.10. What do you mean by pioneer community in water and land ?
2. Give short answers of the followings (any five ) 3x5=15
2.1. Mention any three points of difference between Akinetes and Aplanospore.
2.2. Draw a well labeled diagram of cell structure of Nostoc.
2.3. Explain the structure and function of nucleus.
2.4. Discuss the changes that occur during anaphase of Mitosis.
2.5. Explain food web.
2.6. Explain about the structure and function of plastids .
2.7. What is nitrogen fixtaion ? How is nitrogen fixed in the cell ?
3. What is alternation of generation ?Explain it with suitable diagram in a Funaria ? [7.5]
OR
Explain the characters of the family Gramineae in semi technical terms
with its floral diagram and floral formula . Discuss any two major economic
importance of this family .
4. What is ecosystem ?Discuss the structural and functional aspects of any one ecosystem
you have studied. [8]
Zoology class XI model questions set 5
1. Give very short answers of the followings (any seven) 1x7=7
1.1. Define phylogeny.
1.2. What is Cyclosis in Paramecium.
1.3. What are analogous organ ?Give two examples.
1.4. Give two identifying characters of Echinodermata.
1.5. Mention the classes of phylum Porifera with one example of each .
1.6. What is taxis ?
1.7. Write the meaning of Signet-ring stage.
1.8. Name any endangered animal of Nepal .
1.9. Malarial patient shows the symptoms of malaria in every 48 hours.Why?
1.10. What are nematocysts?
2. Give short answers of the followings (any five ) 3x5=15
2.1. Explain the experiment of Miller Urey .
2.2. Explain the binary fission in paramecium with a well labeled diagram.
2.3. Differentiate between old world monkey and new world monkey.
2.4. Explain the characteristic of leadership.
2.5. Describe the types of migratory fish.
2.6. How sound is produced in frog ?
2.7. Explain different causes of birds migration .
3. Explain the Lemarck’s theory of inheritance of acquired characters with its draw backs. [8]
4. What is portal system ?Describe it with reference to frog . [7.5]
or
Describe the digestive organ of earthworm with a labelled diagram.
Botany class XI model questions set 5
1. Give very short answers of the followings (any seven) 1x7=7
1.1. Name the pigments found in red algae.
1.2. Give the full form of ADP and AMP.
1.3. Give the example of monosacchride and disacchride.
1.4. Give the difference of cisternae and cristae.
1.5. What are leucoplast? Mention their function.
1.6. What is grazing food chain?
1.7. What are primary and secondary myceliums in Agaricus?
1.8. Write two important effect of acid rain.
1.9. How does DNA differ from RNA.
1.10. Which cell organnele is responsible for cell plate formation.
2. Give short answers of the followings (any five ) 3x5=15
2.1. Illustrate the haplo diplo biontic life cycle of yeast .
2.2. Draw well lable diagram of cynobacterical cell .
2.3. What is gametophyte ?Describe it in fern plant .
2.4. Draw outline sketch of 5kingdom classification also mention its basis on which it has been classified.
2.5. Give beneficial aspects of bacteria.
2.6. What are the methods of water resource conservation?
2.7. Draw a labeled diagram of mitotic metaphase and also mention its characteristic.
3. What is mitosis ?explain about the process of mitosis. (7.5)
or
Describe family Cruciferae in semi technical terms with its Floral diagram and floral formula.
4. Describe the nitrogen cycle in nature . (8)
Zoology class XI model questions set 6
1. Give very short answers of the followings (any seven) 1x7=7
1.1. Classify Paramecium in scientific position .
1.2. What do you mean by microbiology.
1.3. What is metamerical segmentation?
1.4. Define Endangered Species .Give scientific names of two endangered species.
1.5. What is taxis ?
1.6. Define the term coelom .Give any two examples of coelomate animals .
1.7. List the classes of phylum mollusca.
1.8. List the type of migration in birds.
1.9. which trait is unique to the human species among primates ?
1.10. Name any two renewable sources of Nepal.
2. Give short answers of the followings (any five ) 3x5=15
2.1. Give some characters of cro-magnon Man.
2.2. Write the objective and conclusion of Urey miller experiment .
2.3. Discuss how fossils give the evidences of evolution .
2.4. Draw a labelled sketch of the TS of gizzard of earthworm.
2.5. Give an account of binary fission of paramecium.
2.6. Describe the aquatic adaptation feature of fishes .
2.7. What are the function of liver in frog?
3. Describe the process of food digestion in frog. [7.5]
or
Describe the life cycle of plasmodium vivax in human body
4. Explain Lamarck's theory of inheritance of acquired character with examples. [8]
Botany class XI model questions set 6
1. Give very short answers of the followings (any seven) 1x7=7
1.1. What is the function of acinates in Nostoc.
1.2. Give types of fruits found in family Gramineae.
1.3. What is lichens?
1.4. Give the meaning of plasmogamy and karyogamy
1.5. What are dwarf shoot in Pinus?
1.6. What is cyclosis?
1.7. What are the characteristic features of telophase of mitosis ?
1.8. What is tetradyanmous condition of stamens
1.9. Define food chain ?
1.10. Write down the pigment and storage food material found in phaeophyceae.
2. Give short answers of the followings (any five ) 3x5=15
2.1. Differentiate between prokaryote and eukaryotic cells.
2.2. Describe the structure of DNA in short .
2.3. How is arcegonium formed in Funaria ?discuss .
2.4. Draw a lable diagram of bacterial cell.
2.5. Compare eukaryotic and prokaryotic cell.
2.6. Describe the vegetative structure of spirogyra .
2.7. Describe the carbon cycle in nature in short.
3. Discuss the prophase I of meiosis with suitable diagram and give differences between mitotic and meiotic prophases .
Or
What is the alternation of generation? Describe the process of alternation of generation with reference to the life cycle of Marchantia.
4. Dicuss how ecosystem is maintained in pond . [8]
Zoology class XI model questions set 7
1. Give very short answers of the followings (any seven) 1x7=7
1.1. Classify Malaria parasite.
1.2. Which pigment gives the dark brown pigmentation in earthworm?
1.3. Give one example of each of class Trematoda and Calcarea.
1.4. Why is responsibility given to human for the protection of earth ?
1.5. Give two important features of java man .
1.6. Name the organelles in Paramecium controlling Osmoregulation and vegetative functions
1.7. What is Neo-Darwinism?
1.8. Give two main identifying characters of Aves.
1.9. Mention the classes of phylum Platyhelminthes.
1.10. Give the position of brain in earth worm.
2. Give short answers of the followings (any five ) 3x5=15
2.1. Give the diagrammatic representation of Miller and Urey experiment in support of biochemical origin of life .
2.2. Describe male reproductive organ of frog in short.
2.3. Describe sporogony of Plasmodium.
2.4. Describe the animal behaviour related to sneezing.
2.5. Explain in brief Oparin Haldane's Theory of Origin of life.
2.6. Give the characteristics of african ape man.
2.7. What are homologous organs? How do homologous organs supports organic evolution?
3. Describe the reproductive organ of earthworm. (7.5)
OR
Describe the structure of heart of frog with well labeled diagram.
4. Write an essay on evolution of man . [8]
Botany class XI model questions set 7
1. Give very short answers of the followings (any seven) 1x7=7
1.1. What are reducing sugars ?
1.2. What is phycology ?
1.3. Why are lichens called bio indicators of air pollution ?
1.4. What is meant by Binomial nomenclature?
1.5. How do you identify Anaphage of mitotic cell division?
1.6. Write the floral formula of Leguminoceae Family.
1.7. What do you understand by green house effect?
1.8. Lysosome is called suicidal bag of cell. why?
1.9. Write the function of heterocyst in nostoc.
1.10. How the glycosidal bond is formed?
2. Give short answers of the followings (any five ) 3x5=15
2.1. Draw a neat floral diagram of crucifera and graminea.
2.2. How does Pioneer Stage from Climax stage in succession.
2.3. Explain the beneficial aspects of bacteria.
2.4. Describe the heterothallic reproduction in spirogyra species.
2.5. Define Primary and secondary succession.
2.6. Describe the structure and function of chloroplast .
2.7. Write down the chromosomal changes found during Pachytine sub stages of prophase I.
3. Describe family Poaceae in semi technical terms with floral formula and diagram .Write botanical name of three economical important plants of this family. [7.5]
or
Describe about sexual life cycle of Spyrogyra with neat and labeled diagram.
4. What is bio geo chemical cycle ?explain the Nitrogen cycle with graphical representation. [8]
Zoology class XI model questions set 8
1. Give very short answers of the followings (any seven) 1x7=7
1.1. What is meant by polyphydont teeth?
1.2. Define alternation of generation .
1.3. Define the term "Incubation period".
1.4. What are apes ?
1.5. With which animal do you fine the following parts .i)muscular foot ii)flame cell.
1.6. Give the scientific name of any two triploblastic insects.
1.7. What does Oparin’s theory suggest ?
1.8. Define the portal system .
1.9. Write the biological name of i)sea-lily ii)jelly-fish .
1.10. What is the nearest ancestor of modern man ?
2. Give short answers of the followings (any five ) 3x5=15
2.1. What are the adaptational features of volant animal?
2.2. Justify "fossil provides incomplete evidence of organic evolution ".
2.3. Write in brief about Pancreas of frog .
2.4. Mention the characteristic of Javaman and Neanderthal man .
2.5. Write in brief sporogony phase of life cycle in plasmodium .
2.6. Enumerate the characters of the phylum Platyhelminthes with two example .
2.7. Discuss the process of spermatogenesis.
3. Describe the process of reproduction of plasmodium in its secondary host. [7.5]
Or
What is portal system ? Discuss that of frog with necessary diagram .
4. Describe Oparin Haldane theory of origin of life. Why is this theory widely accepted? . [8]
Botany class XI model questions set 8
1. Give very short answers of the followings (any seven) 1x7=7
1.1. Write two importances of proteins in organisms.
1.2. Mention major changes occurring at Anaphage of mitosis.
1.3. Give a chief function of Ribosome.
1.4. Mention two methods of forest conservation.
1.5. Give the meaning of hierarchy in taxonomy.
1.6. Write two important characters of Monera.
1.7. Write Floral Formula of mustard plant.
1.8. Mention one important difference between red and brown algae.
1.9. What are the short coming of two -kingdon system of classification ?
1.10. How the peptide bond is formed?
2. Give short answers of the followings (any five ) 3x5=15
2.1. Show the nitrogen cycle diagramatically.
2.2. Explain the prophase 1 of mitotic cell division.
2.3. Describe types of lysosomes and why is it called suicidal bag?
2.4. What do you mean by ozone layer depletion ?Describe its consequences .
2.5. Describe the structure and function of plasma membrane .
2.6. What are proteins ?Discuss their functions .
2.7. Discuss the economical importances of lichens .
3. Describe life cycle of Funaria with graphical representation. [7.5]
Or
Describe family Solanaceae with all necessary diagrams and also mention scientific names of three economical important plants of this family.
4. Define food chain and discuss it with reference of grass land ecosystem . [8]
Zoology class XI model questions set 9
1. Give very short answers of the followings (any seven) 1x7=7
1.1. Give the position of testis and ovary of Pheretima.
1.2. Why does the cross fertilization take place in earthworm?
1.3. Give the biological name of flying lizard and spider.
1.4. Give two examples of endangered species of wildlife.
1.5. Mention the enzyme found in the duodenum.
1.6. Write down the function of ovaries of frog.
1.7. What is vector?
1.8. What is catadromous migration?
1.9. Give two important features of Peking man .
1.10. Give one example of each of class Cestoda and Oligochaeta.
2. Give short answers of the followings (any five ) 3x5=15
2.1. Explain the structure of a tooth in Rana tigrina.
2.2. Mention the characteristic of Neanderthal man .
2.3. Explain the biogenetic law as evidence of organic evolution.
2.4. What are the functions of pancreas in frog?
2.5. Differentiate between old world monkey and new world monkey.
2.6. Write in brief the pre and exo erythrocytic cycle of Plasmodium.
2.7. Explain the relation of biology with other science .
3. Describe the digestive system of earthworm with well labeled diagram. [7.5]
Or
Describe the conjugation in paramecium with necessary diagram .Also give its significance .
4. Describe the Darwin's theory of natural selection . [8]
Botany class XI model questions set 9
1. Give very short answers of the followings (any seven) 1x7=7
1.1. What is capsid ?
1.2. Name the type of vascular bundle found in pinus stem .
1.3. Define taxomomy .
1.4. Give the composition of deoxyribonucleic acid .
1.5. Give the chemical component of virus .
1.6. Define syngenesous anther lobes .
1.7. Name any two micro nutrient and their role .
1.8. Write a difference between mesosomes and ribosomes .
1.9. Name any two human diseases caused by bacteria.
1.10. Define epipetalous stamens.
2. Give short answers of the followings (any five ) 3x5=15
2.1. Justify "viruses are both living and non living body”.
2.2. Define meiosis. Give diagrams for prophase of meiosis I ( no description required )
2.3. Discuss the role of bacteria in medecine.
2.4. Write down the differences between green algae and brown algae .
2.5. Describe the asexual reproduction in mucor.
2.6. Write down the consequence of acid rain.
2.7. Give an account of structure and function of golgi appratus.
3. Describe the family Solanaceae with necessary diagram and mention two economically important plant . [7.5]
Or
Describe lifecycle of mushroom with well labeled diagram.
4. Describe the pond ecosystem with well labelled diagram and mention the flow of energy in trophic level. [8]
Zoology class XI model questions set 10
1. Give very short answers of the followings (any seven) 1x7=7
1.1. Write two important significances of conjugation in Paramecium.
1.2. Give reason "Paramecium is a protistan organism".
1.3. What is alternation of host ?
1.4. Define the term "Incubation period".
1.5. Give the biological name of one flying mammal and one flying reptile.
1.6. Give two examples of endangered birds.
1.7. Mention the enzyme found in the stomach of frog.
1.8. Write down the function of testis of frog.
1.9. What is carrier?
1.10. What is meant by acrodont teeth?
2. Give short answers of the followings (any five ) 3x5=15
2.1. What are the functions of pancreas in frog?
2.2. Differentiate between ape and man.
2.3. Write in brief the erythrocytic cycle of Plasmodium.
2.4. What are the adaptational features of aquatic animal?
2.5. Justify "embryology provides evidence of organic evolution ".
2.6. Mention the characteristic of Australopethicus and Homo habilis .
2.7. Describe the animal behavior in short .
3. Describe the alimentary canal of Frog with suitable diagram. (7.5)
Or
Describe the male and female reproductive system of earthworm.
4. Write an essay on evolution of man starting from Ramapethicus. [8]
Botany class XI model questions set 10
1. Give very short answers of the followings (any seven) 1x7=7
1.1. Give two industrial values of fungi.
1.2. Why are cyanobacteria included in Monera?
1.3. Name the pigment found in red algae .
1.4. Who gave 5 kingdom system of classification and when?
1.5. What is the significance of crossing over in meiosis?
1.6. What are the major Green house gasses ?
1.7. What kinds of fruit is called legume ?
1.8. Give one important function of lysosome.
1.9. Mention two methods of forest conservation.
1.10. What is hierarchy in taxonomy?
2. Give short answers of the followings (any five ) 3x5=15
2.1. What are the economical nature of Bacteria?
2.2. Explain the structure of nucleus ?
2.3. Describe a typical flower in brief.
2.4. Name the different biotic components of the pond ecosystem .
2.5. Explain the beneficial aspects of lichen.
2.6. What are the consequences of ozone layer depletion ?
2.7. Describe the structure and function of plasma membrane in short.
3. Explain the nitrogen cycle in nature with graphical representation. [8]
4. Describe the sexual reproduction in Mucor with diagram. [7.5]
Or
Give the distinguishing character of sub famaly paplionaceae in semi technical term. Give the floral diagram and floral formula as well as any two economical plants of this family
1. Give very short answers of the followings (any seven) 1x7=7
1.1. Classify liver fluke.
1.2. What is adaptational feature of apes .
1.3. List the classes of the phylum Porifera.
1.4. What is sinus venosus ?
1.5. How is the biological science related to physics ?
1.6. What is natural selection ?
1.7. Differentiate between anadromous migration and catadromous migration in fishes .
1.8. Write about the premordial atmosphere of the earth .
1.9. Define homologous organ with example .
1.10. Give scientific name of any two endangered mammal.
2. Give short answers of the followings (any five ) 3x5=15
2.1. What is extinction ?what are the causes of extinction?
2.2. Draw well labeled diagram of alimentary canal of frog.
2.3. Describe in brief the female reproductory organ of female earth worm.
2.4. Discuss the gamogony phase of life cycle of plasmodium vivax.
2.5. Explain the biochemical origin of life.
2.6. Explain the asexual reproduction of paramecium .
2.7. Explain the renal portal system found in frog .
3. What is reproduction ?Describe male reproductive organ of frog
with well label diagram . [7.5]
or
Give an account of conjugation in Paramecium caudatum and discuss its significance.
4.Define evolution .Explain the evolution of man from the pre ape man . [8]
Botany class XI model questions set 1
1. Give very short answers of the followings (any seven) 1x7=7
1.1. Differentiate between primary and secondary succession ?
1.2. Differentiate between primary and secondary succession.
1.3. Define binomial nomenclature .
1.4. What part of moss have diploid cells ?
1.5. Why are the blue green algae blue green in color ?
1.6. Define alternation of generation.
1.7. Define syngenesious stamen .
1.8. Name the chemical components of DNA.
1.9. Name the storage found in green and brown algae .
1.10. What do you mean by tetradynamous stamens ?
2. Give short answers of the followings (any five ) 3x5=15
2.1. Describe and structure and function of amino acids .
2.2. Discuss the changes that occur during metaphase of Mitosis.
2.3. Explain food chain with examples.
2.4. Explain about the structure and function of mitochondria .
2.5. Give beneficial aspects of Lichen.
2.6. What are the methods of forest conservation?
2.7. Draw a labelled diagram of mitotic anaphase and also mention its characteristic.
3. Give the distinguishing character of Solanaceae with its floral formula and floral diagram. Write the scientific name of sunflower , radish, maize and gram. [7.5]
OR
Discuss the vegetative structure and life cycle of mushroom .
4. Define bio geo chemical cycle . Describe nitrogen cycle in nature [8]
Zoology class XI model questions set 2
1. Give very short answers of the followings (any seven) 1x7=7
1.1. Define coacervate.
1.2. Give the function of seminal vesicles of earth worm .
1.3. Define homologous organ with example .
1.4. Name the various forms of locomotory organ found in aquatic animals .
1.5. Name the excretory organ found in Platyhelminthes and Annelids.
1.6. Define Neo Darwinism.
1.7. Define ornithology.
1.8. What was archaeopteryx ?
1.9. What is the functions of akinetes?
1.10. What is reflex action ?
2. Give short answers of the followings (any five ) 3x5=15
2.1. List the Volant adaptational characters of birds.
2.2. Give the significance of archaeopteryx in the study of evolution .
2.3. Explain the relation of biology with other science .
2.4. How exconjugants are formed during conjugation of paramecium ?
2.5. Explain the histological structure of liver of frog .
2.6. "Cro-Magnon is immediate ancestor of modern man " justify.
2.7. Explain the hepatic portal system found in frog .
3. Give an account of the structure of digestive tract of Pheretima. [7.5]
OR
Describe the structure of heart of frog with necessary diagram
4. Write an Essay on Darwinism. [8]
Botany class XI model questions set 2
1. Give very short answers of the followings (any seven) 1x7=7
1.1. Define the terms phycology and mycology.
1.2. Why yeast placed in fungi?
1.3. What is cell theory ?
1.4. Name two chemical components in the structure of virus.
1.5. In which food chain pyramid of number is inverted?
1.6. Name two economically important fungi.
1.7. State what spiklet inflorescence is.
1.8. Name four green house gasses .
1.9. Define the term coenocytic hypha.
1.10. What is acid rain ?
2. Give short answers of the followings (any five ) 3x5=15
2.1. Differentiate between mitotic and meiotic cell division.
2.2. Describe and structure and function of amino acids .
2.3. What is pesticides? What are the hazards caused by pesticides?
2.4. List the characteristics of gymnosperm .
2.5. Write briefly about the structure and function of nucleus .
2.6. Draw diagrammatic life cycle of Funaria . No description is needed .
2.7. Discuss the consequence of ozone layer depletion .
3. Give the distinguishing character of solanaceae with its floral formula and floral diagram. Write the scientific name of sunflower , radish, maize and gram[7.5]
Or
Discuss the vegetative structure and life cycle of mushroom .
4. Define bio geo chemical cycle . Describe nitrogen cycle in nature [8]
Zoology class XI model questions set 3
1. Give very short answers of the followings (any seven) 1x7=7
1.1. Give the scientific name of tapeworm and wall lizard.
1.2. Discuss the role of variation in organic evolution .
1.3. How do insects differ from Arachnida?
1.4. Define fossil.
1.5. What are early primates resemble to ?
1.6. Give two example of vestigial organ.
1.7. What is reflex arc?
1.8. What is the function of choanoderm in Porifera?
1.9. Who suggested that monkeys, apes and man have a common ancestor ?
1.10. Name the muscles that controls the setae of earthworm .
2. Give short answers of the followings (any five ) 3x5=15
2.1. Explain arboreal adaptation among reptiles.
2.2. Give an account on Australopithecus.
2.3. Represent diagrammatically the process of conjugation in paramecium .
2.4. Write in brief the erythrocytic cycle of Plasmodium.
2.5. Describe the experiment of Urey miller for the origin of life .
2.6. Differentiate between chondrichthys and oesteichtys fish .
2.7. Give the adaptational modifications found in scansorial animals .
3. Describe the reproductive organ of earthworm. [7.5]
Or
Describe the internal structure of heart in frog and give its working mechanism.
4. Write an Essay on Lamarckism. Write down the demerits of this theory and about the Neo Lamarckism. [8]
Botany class XI model questions set 3
1. Give very short answers of the followings (any seven) 1x7=7
1.1. What is the function of heterocyst?
1.2. Name two edible mushroom available in market .
1.3. Why is Spirogyra placed in algae?
1.4. Name two type recemose inflorescence you have studied.
1.5. Name the chemical components of RNA.
1.6. Name the storage found in green and brown algae .
1.7. What do you mean by tetradynamous stamens ?
1.8. Mention any two points of differences between primary and secondary mycelium.
1.9. Name the major components of virus .
1.10. Define the term nucleotide.
2. Give short answers of the followings (any five ) 3x5=15
2.1. Discuss the economic importance of fungi.
2.2. Give the structure and function of Golgi complex.
2.3. Differentiate between metaphase I and metaphase II of meiosis.
2.4. State the economic importance of the family solanaceae.
2.5. Draw diagrammatic life cycle of spirogyra. (no description)
2.6. Discuss the consequences of acid rain .
2.7. Explain the structure and functions of mitochondria.
3. What is altenation of generation ?Explain it with suitable diagram in a Marchantia. [7.5]
OR
Explain the characters of the family Papilionaceae in semitechnical term
with floral diagram and floral formula .Discuss any two major importance
of this family .
4. What is energy flow .Explain how it takes place in terrestrial ecosystem. [8]
Zoology class XI model questions set 4
1. Give very short answers of the followings (any seven) 1x7=7
1.1. Give scientific names of any two endangered mammals of Nepal.
1.2. Define Osteology.
1.3. Which technique is used to know the age of fossils ?
1.4. Give the functions of Typhlosole in Earth worm.
1.5. Write Scientific names of frog and star fish.
1.6. What do you mean by the word Arthropoda?
1.7. What is adaptation?
1.8. What is catadromous migration?
1.9. What is serological test?
1.10. What is torsion ? Give one example of animal which shows torsion .
2. Give short answers of the followings (any five ) 3x5=15
2.1. Discuss about the Cro magnon man.
2.2. Give the characteristic feature of class Aves.
2.3. Draw a neat and labeled diagram of Paramecium.
2.4. Give the functions of skin of earthworm.
2.5. How does cocoon formation takes place in earthworm?
2.6. Give a brief description of the T.S. of the testis of frog with neat labeled diagram.
2.7. Enumerate the characters of Annelida .
3. Give an account of life cycle of Plasmodium in man . [7.5]
OR
Discuss the reproductive system of Frog.
4. What is organic evolution ?Trace out evolution of man starting from Ramapethicus . [8]
Botany class XI model questions set 4
1. Give very short answers of the followings (any seven) 1x7=7
1.1. Define net primary productivity.
1.2. What is trophic level.
1.3. What do you mean by succession?
1.4. Why is lysosomes called as suicidal bag ?
1.5. Write any two consequence of acid rain.
1.6. Mention the chemical components of virus.
1.7. Write the meaning of syngenesis.
1.8. What is the function of pyrenoid ?
1.9. What is nucleotides ?
1.10. What do you mean by pioneer community in water and land ?
2. Give short answers of the followings (any five ) 3x5=15
2.1. Mention any three points of difference between Akinetes and Aplanospore.
2.2. Draw a well labeled diagram of cell structure of Nostoc.
2.3. Explain the structure and function of nucleus.
2.4. Discuss the changes that occur during anaphase of Mitosis.
2.5. Explain food web.
2.6. Explain about the structure and function of plastids .
2.7. What is nitrogen fixtaion ? How is nitrogen fixed in the cell ?
3. What is alternation of generation ?Explain it with suitable diagram in a Funaria ? [7.5]
OR
Explain the characters of the family Gramineae in semi technical terms
with its floral diagram and floral formula . Discuss any two major economic
importance of this family .
4. What is ecosystem ?Discuss the structural and functional aspects of any one ecosystem
you have studied. [8]
Zoology class XI model questions set 5
1. Give very short answers of the followings (any seven) 1x7=7
1.1. Define phylogeny.
1.2. What is Cyclosis in Paramecium.
1.3. What are analogous organ ?Give two examples.
1.4. Give two identifying characters of Echinodermata.
1.5. Mention the classes of phylum Porifera with one example of each .
1.6. What is taxis ?
1.7. Write the meaning of Signet-ring stage.
1.8. Name any endangered animal of Nepal .
1.9. Malarial patient shows the symptoms of malaria in every 48 hours.Why?
1.10. What are nematocysts?
2. Give short answers of the followings (any five ) 3x5=15
2.1. Explain the experiment of Miller Urey .
2.2. Explain the binary fission in paramecium with a well labeled diagram.
2.3. Differentiate between old world monkey and new world monkey.
2.4. Explain the characteristic of leadership.
2.5. Describe the types of migratory fish.
2.6. How sound is produced in frog ?
2.7. Explain different causes of birds migration .
3. Explain the Lemarck’s theory of inheritance of acquired characters with its draw backs. [8]
4. What is portal system ?Describe it with reference to frog . [7.5]
or
Describe the digestive organ of earthworm with a labelled diagram.
Botany class XI model questions set 5
1. Give very short answers of the followings (any seven) 1x7=7
1.1. Name the pigments found in red algae.
1.2. Give the full form of ADP and AMP.
1.3. Give the example of monosacchride and disacchride.
1.4. Give the difference of cisternae and cristae.
1.5. What are leucoplast? Mention their function.
1.6. What is grazing food chain?
1.7. What are primary and secondary myceliums in Agaricus?
1.8. Write two important effect of acid rain.
1.9. How does DNA differ from RNA.
1.10. Which cell organnele is responsible for cell plate formation.
2. Give short answers of the followings (any five ) 3x5=15
2.1. Illustrate the haplo diplo biontic life cycle of yeast .
2.2. Draw well lable diagram of cynobacterical cell .
2.3. What is gametophyte ?Describe it in fern plant .
2.4. Draw outline sketch of 5kingdom classification also mention its basis on which it has been classified.
2.5. Give beneficial aspects of bacteria.
2.6. What are the methods of water resource conservation?
2.7. Draw a labeled diagram of mitotic metaphase and also mention its characteristic.
3. What is mitosis ?explain about the process of mitosis. (7.5)
or
Describe family Cruciferae in semi technical terms with its Floral diagram and floral formula.
4. Describe the nitrogen cycle in nature . (8)
Zoology class XI model questions set 6
1. Give very short answers of the followings (any seven) 1x7=7
1.1. Classify Paramecium in scientific position .
1.2. What do you mean by microbiology.
1.3. What is metamerical segmentation?
1.4. Define Endangered Species .Give scientific names of two endangered species.
1.5. What is taxis ?
1.6. Define the term coelom .Give any two examples of coelomate animals .
1.7. List the classes of phylum mollusca.
1.8. List the type of migration in birds.
1.9. which trait is unique to the human species among primates ?
1.10. Name any two renewable sources of Nepal.
2. Give short answers of the followings (any five ) 3x5=15
2.1. Give some characters of cro-magnon Man.
2.2. Write the objective and conclusion of Urey miller experiment .
2.3. Discuss how fossils give the evidences of evolution .
2.4. Draw a labelled sketch of the TS of gizzard of earthworm.
2.5. Give an account of binary fission of paramecium.
2.6. Describe the aquatic adaptation feature of fishes .
2.7. What are the function of liver in frog?
3. Describe the process of food digestion in frog. [7.5]
or
Describe the life cycle of plasmodium vivax in human body
4. Explain Lamarck's theory of inheritance of acquired character with examples. [8]
Botany class XI model questions set 6
1. Give very short answers of the followings (any seven) 1x7=7
1.1. What is the function of acinates in Nostoc.
1.2. Give types of fruits found in family Gramineae.
1.3. What is lichens?
1.4. Give the meaning of plasmogamy and karyogamy
1.5. What are dwarf shoot in Pinus?
1.6. What is cyclosis?
1.7. What are the characteristic features of telophase of mitosis ?
1.8. What is tetradyanmous condition of stamens
1.9. Define food chain ?
1.10. Write down the pigment and storage food material found in phaeophyceae.
2. Give short answers of the followings (any five ) 3x5=15
2.1. Differentiate between prokaryote and eukaryotic cells.
2.2. Describe the structure of DNA in short .
2.3. How is arcegonium formed in Funaria ?discuss .
2.4. Draw a lable diagram of bacterial cell.
2.5. Compare eukaryotic and prokaryotic cell.
2.6. Describe the vegetative structure of spirogyra .
2.7. Describe the carbon cycle in nature in short.
3. Discuss the prophase I of meiosis with suitable diagram and give differences between mitotic and meiotic prophases .
Or
What is the alternation of generation? Describe the process of alternation of generation with reference to the life cycle of Marchantia.
4. Dicuss how ecosystem is maintained in pond . [8]
Zoology class XI model questions set 7
1. Give very short answers of the followings (any seven) 1x7=7
1.1. Classify Malaria parasite.
1.2. Which pigment gives the dark brown pigmentation in earthworm?
1.3. Give one example of each of class Trematoda and Calcarea.
1.4. Why is responsibility given to human for the protection of earth ?
1.5. Give two important features of java man .
1.6. Name the organelles in Paramecium controlling Osmoregulation and vegetative functions
1.7. What is Neo-Darwinism?
1.8. Give two main identifying characters of Aves.
1.9. Mention the classes of phylum Platyhelminthes.
1.10. Give the position of brain in earth worm.
2. Give short answers of the followings (any five ) 3x5=15
2.1. Give the diagrammatic representation of Miller and Urey experiment in support of biochemical origin of life .
2.2. Describe male reproductive organ of frog in short.
2.3. Describe sporogony of Plasmodium.
2.4. Describe the animal behaviour related to sneezing.
2.5. Explain in brief Oparin Haldane's Theory of Origin of life.
2.6. Give the characteristics of african ape man.
2.7. What are homologous organs? How do homologous organs supports organic evolution?
3. Describe the reproductive organ of earthworm. (7.5)
OR
Describe the structure of heart of frog with well labeled diagram.
4. Write an essay on evolution of man . [8]
Botany class XI model questions set 7
1. Give very short answers of the followings (any seven) 1x7=7
1.1. What are reducing sugars ?
1.2. What is phycology ?
1.3. Why are lichens called bio indicators of air pollution ?
1.4. What is meant by Binomial nomenclature?
1.5. How do you identify Anaphage of mitotic cell division?
1.6. Write the floral formula of Leguminoceae Family.
1.7. What do you understand by green house effect?
1.8. Lysosome is called suicidal bag of cell. why?
1.9. Write the function of heterocyst in nostoc.
1.10. How the glycosidal bond is formed?
2. Give short answers of the followings (any five ) 3x5=15
2.1. Draw a neat floral diagram of crucifera and graminea.
2.2. How does Pioneer Stage from Climax stage in succession.
2.3. Explain the beneficial aspects of bacteria.
2.4. Describe the heterothallic reproduction in spirogyra species.
2.5. Define Primary and secondary succession.
2.6. Describe the structure and function of chloroplast .
2.7. Write down the chromosomal changes found during Pachytine sub stages of prophase I.
3. Describe family Poaceae in semi technical terms with floral formula and diagram .Write botanical name of three economical important plants of this family. [7.5]
or
Describe about sexual life cycle of Spyrogyra with neat and labeled diagram.
4. What is bio geo chemical cycle ?explain the Nitrogen cycle with graphical representation. [8]
Zoology class XI model questions set 8
1. Give very short answers of the followings (any seven) 1x7=7
1.1. What is meant by polyphydont teeth?
1.2. Define alternation of generation .
1.3. Define the term "Incubation period".
1.4. What are apes ?
1.5. With which animal do you fine the following parts .i)muscular foot ii)flame cell.
1.6. Give the scientific name of any two triploblastic insects.
1.7. What does Oparin’s theory suggest ?
1.8. Define the portal system .
1.9. Write the biological name of i)sea-lily ii)jelly-fish .
1.10. What is the nearest ancestor of modern man ?
2. Give short answers of the followings (any five ) 3x5=15
2.1. What are the adaptational features of volant animal?
2.2. Justify "fossil provides incomplete evidence of organic evolution ".
2.3. Write in brief about Pancreas of frog .
2.4. Mention the characteristic of Javaman and Neanderthal man .
2.5. Write in brief sporogony phase of life cycle in plasmodium .
2.6. Enumerate the characters of the phylum Platyhelminthes with two example .
2.7. Discuss the process of spermatogenesis.
3. Describe the process of reproduction of plasmodium in its secondary host. [7.5]
Or
What is portal system ? Discuss that of frog with necessary diagram .
4. Describe Oparin Haldane theory of origin of life. Why is this theory widely accepted? . [8]
Botany class XI model questions set 8
1. Give very short answers of the followings (any seven) 1x7=7
1.1. Write two importances of proteins in organisms.
1.2. Mention major changes occurring at Anaphage of mitosis.
1.3. Give a chief function of Ribosome.
1.4. Mention two methods of forest conservation.
1.5. Give the meaning of hierarchy in taxonomy.
1.6. Write two important characters of Monera.
1.7. Write Floral Formula of mustard plant.
1.8. Mention one important difference between red and brown algae.
1.9. What are the short coming of two -kingdon system of classification ?
1.10. How the peptide bond is formed?
2. Give short answers of the followings (any five ) 3x5=15
2.1. Show the nitrogen cycle diagramatically.
2.2. Explain the prophase 1 of mitotic cell division.
2.3. Describe types of lysosomes and why is it called suicidal bag?
2.4. What do you mean by ozone layer depletion ?Describe its consequences .
2.5. Describe the structure and function of plasma membrane .
2.6. What are proteins ?Discuss their functions .
2.7. Discuss the economical importances of lichens .
3. Describe life cycle of Funaria with graphical representation. [7.5]
Or
Describe family Solanaceae with all necessary diagrams and also mention scientific names of three economical important plants of this family.
4. Define food chain and discuss it with reference of grass land ecosystem . [8]
Zoology class XI model questions set 9
1. Give very short answers of the followings (any seven) 1x7=7
1.1. Give the position of testis and ovary of Pheretima.
1.2. Why does the cross fertilization take place in earthworm?
1.3. Give the biological name of flying lizard and spider.
1.4. Give two examples of endangered species of wildlife.
1.5. Mention the enzyme found in the duodenum.
1.6. Write down the function of ovaries of frog.
1.7. What is vector?
1.8. What is catadromous migration?
1.9. Give two important features of Peking man .
1.10. Give one example of each of class Cestoda and Oligochaeta.
2. Give short answers of the followings (any five ) 3x5=15
2.1. Explain the structure of a tooth in Rana tigrina.
2.2. Mention the characteristic of Neanderthal man .
2.3. Explain the biogenetic law as evidence of organic evolution.
2.4. What are the functions of pancreas in frog?
2.5. Differentiate between old world monkey and new world monkey.
2.6. Write in brief the pre and exo erythrocytic cycle of Plasmodium.
2.7. Explain the relation of biology with other science .
3. Describe the digestive system of earthworm with well labeled diagram. [7.5]
Or
Describe the conjugation in paramecium with necessary diagram .Also give its significance .
4. Describe the Darwin's theory of natural selection . [8]
Botany class XI model questions set 9
1. Give very short answers of the followings (any seven) 1x7=7
1.1. What is capsid ?
1.2. Name the type of vascular bundle found in pinus stem .
1.3. Define taxomomy .
1.4. Give the composition of deoxyribonucleic acid .
1.5. Give the chemical component of virus .
1.6. Define syngenesous anther lobes .
1.7. Name any two micro nutrient and their role .
1.8. Write a difference between mesosomes and ribosomes .
1.9. Name any two human diseases caused by bacteria.
1.10. Define epipetalous stamens.
2. Give short answers of the followings (any five ) 3x5=15
2.1. Justify "viruses are both living and non living body”.
2.2. Define meiosis. Give diagrams for prophase of meiosis I ( no description required )
2.3. Discuss the role of bacteria in medecine.
2.4. Write down the differences between green algae and brown algae .
2.5. Describe the asexual reproduction in mucor.
2.6. Write down the consequence of acid rain.
2.7. Give an account of structure and function of golgi appratus.
3. Describe the family Solanaceae with necessary diagram and mention two economically important plant . [7.5]
Or
Describe lifecycle of mushroom with well labeled diagram.
4. Describe the pond ecosystem with well labelled diagram and mention the flow of energy in trophic level. [8]
Zoology class XI model questions set 10
1. Give very short answers of the followings (any seven) 1x7=7
1.1. Write two important significances of conjugation in Paramecium.
1.2. Give reason "Paramecium is a protistan organism".
1.3. What is alternation of host ?
1.4. Define the term "Incubation period".
1.5. Give the biological name of one flying mammal and one flying reptile.
1.6. Give two examples of endangered birds.
1.7. Mention the enzyme found in the stomach of frog.
1.8. Write down the function of testis of frog.
1.9. What is carrier?
1.10. What is meant by acrodont teeth?
2. Give short answers of the followings (any five ) 3x5=15
2.1. What are the functions of pancreas in frog?
2.2. Differentiate between ape and man.
2.3. Write in brief the erythrocytic cycle of Plasmodium.
2.4. What are the adaptational features of aquatic animal?
2.5. Justify "embryology provides evidence of organic evolution ".
2.6. Mention the characteristic of Australopethicus and Homo habilis .
2.7. Describe the animal behavior in short .
3. Describe the alimentary canal of Frog with suitable diagram. (7.5)
Or
Describe the male and female reproductive system of earthworm.
4. Write an essay on evolution of man starting from Ramapethicus. [8]
Botany class XI model questions set 10
1. Give very short answers of the followings (any seven) 1x7=7
1.1. Give two industrial values of fungi.
1.2. Why are cyanobacteria included in Monera?
1.3. Name the pigment found in red algae .
1.4. Who gave 5 kingdom system of classification and when?
1.5. What is the significance of crossing over in meiosis?
1.6. What are the major Green house gasses ?
1.7. What kinds of fruit is called legume ?
1.8. Give one important function of lysosome.
1.9. Mention two methods of forest conservation.
1.10. What is hierarchy in taxonomy?
2. Give short answers of the followings (any five ) 3x5=15
2.1. What are the economical nature of Bacteria?
2.2. Explain the structure of nucleus ?
2.3. Describe a typical flower in brief.
2.4. Name the different biotic components of the pond ecosystem .
2.5. Explain the beneficial aspects of lichen.
2.6. What are the consequences of ozone layer depletion ?
2.7. Describe the structure and function of plasma membrane in short.
3. Explain the nitrogen cycle in nature with graphical representation. [8]
4. Describe the sexual reproduction in Mucor with diagram. [7.5]
Or
Give the distinguishing character of sub famaly paplionaceae in semi technical term. Give the floral diagram and floral formula as well as any two economical plants of this family
Sunday, September 19, 2010
for BLAS students
model questions
Long question 20 Marks each
1. Describe the Oparin Haldane theory of origin of life.
2. Describe the Mendel’s Laws of Inheritance.
3. Describe the theory of Natural selection with its limitation.
4. Discuss the various scopes of Natural science.
5. Discuss the strategies in the management of wildlife in Nepal.
6. What is Law of Independent Assortment? Describe it with dihybrid cross of Mendel’s experiment.
Short questions (attempt any five) 8 marks each
1. How is Chemistry related with Biology?
2. Write short notes on spontaneous generation.
3. Describe Miller Urey experiment about origin of life.
4. Illustrate the use and disuse of organ in Lamarckism
5. Write a short note on survival of the fittest.
6. Describe Redi’s experiment. How does it prove Biogenesis?
7. Give the meaning of a) Punnet Square b) Genotype
8. Describe the monohybrid cross of Mendel’s experiment.
9. Describe the dihybrid cross of Mendel’s experiment.
10. Why did Mendel select pea plant for his experiment.
11. Write down the role of forest.
12. Write down the role of the river.
13. Write short account of any one National Park of Nepal.
14. What are the causes of Flood.
15. What are the strategies in the management of landslides
16. What are the protective measures to be carried out at the time of earth quake?
17. Why are mountains important to us?
18. How are the Himalayas different from mountains?
19. Write short note on mountain ecosystem
20. Write consequences of deforestation
21. Write short notes on Special Creation Theory regarding origin of life.
22. The giraffe has long neck and long fore limb. What do this prove.?
23. Why have snakes lost legs?
24. Give name of four endangered animals of Nepal and causes of being endangered.
Long question 20 Marks each
1. Describe the Oparin Haldane theory of origin of life.
2. Describe the Mendel’s Laws of Inheritance.
3. Describe the theory of Natural selection with its limitation.
4. Discuss the various scopes of Natural science.
5. Discuss the strategies in the management of wildlife in Nepal.
6. What is Law of Independent Assortment? Describe it with dihybrid cross of Mendel’s experiment.
Short questions (attempt any five) 8 marks each
1. How is Chemistry related with Biology?
2. Write short notes on spontaneous generation.
3. Describe Miller Urey experiment about origin of life.
4. Illustrate the use and disuse of organ in Lamarckism
5. Write a short note on survival of the fittest.
6. Describe Redi’s experiment. How does it prove Biogenesis?
7. Give the meaning of a) Punnet Square b) Genotype
8. Describe the monohybrid cross of Mendel’s experiment.
9. Describe the dihybrid cross of Mendel’s experiment.
10. Why did Mendel select pea plant for his experiment.
11. Write down the role of forest.
12. Write down the role of the river.
13. Write short account of any one National Park of Nepal.
14. What are the causes of Flood.
15. What are the strategies in the management of landslides
16. What are the protective measures to be carried out at the time of earth quake?
17. Why are mountains important to us?
18. How are the Himalayas different from mountains?
19. Write short note on mountain ecosystem
20. Write consequences of deforestation
21. Write short notes on Special Creation Theory regarding origin of life.
22. The giraffe has long neck and long fore limb. What do this prove.?
23. Why have snakes lost legs?
24. Give name of four endangered animals of Nepal and causes of being endangered.
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