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UNIVERSAL EDUCATION ICSE GRADE X SUBJECT : BIOLOGY ___________________________________________________________________________ Chapter 9 - Nervous system Q1. Name the following 1. The part of the brain which is considered with muscular coordination in the body Cerebellum 2. The structure for the alteration of the shape of the lens Ciliary body 3. The structure for the constriction of the pupil in the bright light Iris 4. The nerve which transmits impulse from the eye to the brain Optic nerve 5. The unit of nervous system Neuron 6. The neuron which transmits impulse from the brain to the effector organ Motor neuron 7. The lower part of the brain that contains reflex centre Spinal cord 8. The middle coat of the eye Choroid 9. The smallest bone in the body Stapes 10. Response to a stimulus without the intervention of the will of an animal Reflex action 11. One neurotransmitter Acetylcholine 12. A bony socket in which the eye is well protected Orbit 13. A small opening in the centre of the iris Pupil 14. The organ of hearing Ear 15. The structure that has a sensory organ called organ of corti Cochlea 16. The defect of the eye caused due to uneven curvature of the cornea Astigmatism 17. The nature of image formed on the retina Real, inverted and diminished. 18. The fluid that is present in the brain Cerebrospinal fluid 19. The part of the brain which controls the activities of the internal organ Medulla oblongata 20. The part of the brain which helps in maintaining the balance of the body Cerebellum Q.2] Select the correct answer out of the four available choices given under each question. 1. Which part of the ear passes sound waves from the outer to the middle ear a. Eustachian tube, b. ear drum, c. oval window, d. pinna Ans ear drum 2. Adjustment of the eye in the normal person to view near and distant object is called a. accommodation , b. myopia, c. refraction, d. astigmatism Ans accommodation 3. The condition in which light rays from the distant object are brought into focus in front of the retina is called a. astigmatism, b. myopia, c. accommodation, d. refraction Ans myopia 4. The dorsal root ganglion of the spinal cord contain cell bodies of a. motor neurons, b. sensory neurons, c. association neuron, d. none of these Ans - sensory neurons 5. Which one of these receptors in man is stimulated by sound waves a. utriculus, b. organ of corti, c. semicircular canal, d. sacculus Ans - organ of corti 6. To view distant object the lens of the eye becomes a. more convex, b. less convex, c. more concave, d. less concave Ans - more convex 7. Function of the iris is to a. move the lens, b. alter the diameter of the pupil, c. close the eyelid, d. secrete aqueous humor Ans - alter the diameter of the pupil 8. Which one of the following is not involved in the knee jerk reflex a. spinal cord, b. motor neuron, c. connecting neuron, d. sensory neuron Ans - connecting neuron 9. Blind spot in an eye is located a. in fovea centralis, b. in middle of the lens, c. where optic nerve leaves the retina, d. in centre of the pupil Ans - where optic nerve leaves the retina Q.3 Complete the following statements. 1. Brain and spinal cord are the parts of the sympathetic system. 2. Cerebrum is the largest part of the brain. 3. A bundle of axons enclosed in the tubular sheath is called as nerve. 4. Long thread like part of the nerve cell is called axon. 5. Yellow spot is the place of best vision in the retina. 6. Place of no vision in the retina of the eye is blind spot. 7. Capacity of the eye to focus at different distances is power of accommodation. 8. The cavities of the brain are called as ventricles. 9. The meninges include pia mater, arachnoid and dura mater. 10. 11. 12. 13. 14. 15. 16. 17. 18. 19. 20. The three layers of the eye include sclera, choroid and retina. The three small bones in the middle ear are called ear ossicles. Cochlea is filled with endolymph. Tympanic chamber is filled with perilymph. The spinal cord is the centre of reflex action. The thin transparent membrane covering the eye is conjunctiva. The middle ear is separated from the external ear by tympanic membrane. Organ of hearing is cochlea. Passage connecting middle ear and pharynx is called as Eustachian tube. In color blindness person cannot distinguish between red and green color. Spiral canal located in the internal ear cochlea. Q.4] State whether the following statement are true or false. If false correct the statement. 1. Cranial nerves arise from the brain True. 2. A convex lens is used for correcting myopia False, concave lens is used for correcting myopia. 3. Hypermetropia is a defect of the eye ball being elongated False, Hypermetropia is a defect of the eye ball being flat. 4. Deafness is caused due to rupturing of the pinna False, Deafness is caused due to rupturing of the eardrum. 5. Cochlea of the human ear is concerned with the sense of balance False, Cochlea of the human ear is concerned with sense of hearing. 6. Salivation at the smell of food is a natural reflex False, Salivation at the smell of food is a conditional reflex. 7. The unit of nervous system is neuron True. 8. The element needed for the transmission of the impulse is sodium True. 9. The middle ear contains cochlea False, the middle ear contains ear ossicle. 10. Spinal nerves are twelve pairs False, Spinal nerves are 31 pairs. Q.5] Define the following. 1) Synapse Ans. Synapse is the point of contact between the terminal branches of the axon of a neuron with the dendrites of another neuron separated by a fine gap. 2) Yellow spot Ans. It is the point on the retina where best vision is possible. 3) Power of accommodation Ans. It is the ability of the eye lens to view an object at different distances. 4) Nerve Ans. Nerve is a bundle of nerve fiber of separate neurons enclosed in a tubular sheath. 5) Retina Ans. It is the innermost light sensitive coat of the eyeball. 6) Iris Ans. The pigmented area in choroid of the eye. It controls the quality of light that will reach the retina. 7. Ganglia Ans. Ganglia are the aggregates of the nerve cells from which the nerve fibers may arise or enter into. 8. Reflex action Ans. Reflex action is an automatic, quick and voluntary action in the body brought about by a stimulus. 9. Conditioned reflex Ans. A conditioned reflex is an involuntary, spontaneous automatic response brought about due to a previously learned experience. 10. Stimulus Ans. A stimulus is any agent or an environmental change which initiates a response in the body. Q.6] State one main function of the following. 1. Neuron Ans. Conduction of nerve impulses. 2. Myelin sheath Ans. It insulates the axon. 3. Acetylcholine Ans. It sets a new impulse in the dendrites of the adjacent neuron. 4. Cerebrum Ans. Seat of memory, speech, reasoning, etc. 5. Cerebellum Ans. It controls body equilibrium. 6. Medulla oblongata Ans. Controls all involuntary activities. 7. Spinal cord Ans. It controls the reflex action. 8. Iris Ans. It controls the size of pupil. 9. Cornea Ans. It refracts the light rays entering the pupil 10. Retina Ans. It helps in the formation of image. 11. Optic nerve Ans. It carries impulse from eye to the brain. 12. Ear drum Ans. It receive the vibrations from the auditory canal and transmit to the ear ossicles. 13. Organ of corti Ans. It helps in hearing. 14. Auditory nerve Ans. To carry impulse from the internal ear to the brain. 15. Semicircular canal Ans. These are concerned with body equilibrium. 16. Thalamus Ans. It is the relay centre to cerebrum for pain and pressure. 17. Hypothalamus Ans. It controls the body temperature and controls the pituitary gland. Q.7] State differences between the following pair. 1. Sensory neuron Motor neurom transmits stimulus from the receptor transmits stimulus from the CNS organ organ to CNS to receptor 2. Sympathetic nervous system Parasympathetic nervous system Prepares the body for an abnormal Prepares the body for the normal situation functioning after abnormal situation 3. Simple reflex Conditioned reflex These are inborn reflexes These are acquired reflexes 4. Myopia Hypermetropia The image of distant object is formed in The image of near object of formed behind front of the retina the retina 5. Central nervous system Peripheral nervous system It consist of brain and spinal cord Consist of cranial and spinal nerve It contains centers for controlling These nerves can only transmit the nerve various activities of the body impulse. 6. Dendrite Axon These are many short branched It is the only one long process going away processes present in the nerve cell body Through dendrites messages are received from the nerve cell body. Through axon the messages leave the cell to another nerve cell. Reflex action It is an unconscious or involuntary action and it takes place quickly It originates from the receptor organ Voluntary action It is a conscious action bringing a desired movement of the body It originates from the brain White matter It is composed of axons from the nerve cell It is inside the brain but outside the spinal cord Grey matter It is composed of cell body of a nerve cell Rods Rods are insensitive to colour Cones Cones are sensitive to colour and are responsible for colour vision They contain a pigment called iodopsin. 7. 8. It is outside the brain but inside the spinal cord 9. They contain photo pigment called rhodopsin 10. Blind spot It is insensitive to light and so no image is formed It is present at the entry of optic nerve just below the yellow spot Yellow spot It is sensitive to light and so a distinct image is formed It is present exactly opposite to the center of the lens in the retina Myopia The image of distant object is formed in front and not on the retina It is corrected by use of biconcave lens Hypermetropia The image of distant object is formed beyond the retina It is corrected by use of biconvex lens 11. Q.8] Answer the following question briefly 1. What is corpus callosum? A transverse band of nervous tissue connecting the left and the right cerebral hemisphere is called as corpus callosum. 2. What is cerebrospinal fluid? It is fluid present in the cerebrospinal cavity of the brain which lubricates the brain and functions as a mechanical shock absorber. 3. What are meninges? The protective membrane covering the brain and the spinal cord. 4. What is pons varoli? The broad bridge of fibers that connect the two hemispheres of the hind brain is called as pons varoli. It serves as a relay centre. 5. What is reflex action The spontaneous, automatic and involuntary action in the body brought about by the stimulus. 6. What is reflex arc? It is the shortest route that can be taken by an impulse from a receptor to an effector. 7. What is binocular vision? Simultaneous focusing of an object in both the eyes and their images by overlapping in the brain. 8. What is night blindness? It is the condition of the eye in which a person cannot view objects during night or in the dim light. 9. What is Eustachian tube? It is present in the middle ear and connects the cavity of the middle ear with the throat. 10. What is light adaptation? When person moves from the dark area to the lighted area he experiences the dazzling effect for a short period of time and becomes normal after a short period. The adaptation of the eye is called light adaptation. 11. What is myopia? It is a defect of the eye in which a person can see nearby things but cannot see the distant object. 12. What is Hypermetropia? It is a defect of the eye in which a person can see distant things but cannot see the nearby object. 13. What is response? The change or the reaction brought in an organism by stimulus is called as response. 14. Name the type of response depending upon the nerve impulse. Sensory neuron Motor neuron Association neuron. 15. Name the different types of nerve fibers. Sensory nerve Motor nerve Mixed nerve 16. What is Hypermetropia? It is a defect of the eye in which a person can see image of distant object but fail to see nearby objects. 17. What is myopia? It is a defect of the eye when a person can see clearly near objects but m=not the distant objects. 18. What is astigmatism? It is the defect of the eye when the image is not properly focused in the different axes due to unevenness of the lenses or the cornea. Q.9] Answers based on diagram 1. Draw a well labeled diagram of a neuron showing the following parts. cyton, axon, dendrites, Node of Ranvier, and myelin sheath. 2. The diagram shows the section of the human brain. Answer the question that follows. 1. Name the parts labeled as A, B and C. A- Cerebrum B- Cerebellum C- Medulla oblongata. 2. Give the main functions of each of the following parts labeled above. Cerebrum seat of memory, reason and logic Cerebellum controls body balance Medulla oblongata controls involuntary actions. 3. Name the three protective covering membranes of the brain. Dura mater Arachnoid Pia mater. 4. Name the basic unit of the brain. Neuron. 3. The diagram given below represents the structure found in the inner ear. Study the same and then answer the following. 1. Name the parts labeled as A, B, C and D. A- Semi-circular canal B- Utriculus C- Sacculus D- Cochlea. 2. Name nerve that conducts impulse to the brain. Auditory nerve 3. Name the audio receptor cells which pick up vibrations. Sensory cells of the organ of corti 4. Name the fluid present in the inner ear. Perilymph 4. Given below is the diagram depicting a defect of the human eye. Study the same and answer the questions that follow. 1. Identify the defect. Myopia 2. Name the parts labeled as 1, 2, and 3. 1. Vitreous humor 2. Fovea 3. Optic nerve 3. Give two possible reasons for the eye defect. 1. Lengthening of the eye ball from front to back 2. Lens is too curved. 4. Draw a diagram to show the correction. 5. Draw diagram of the human eye as seen in the vertical section and label the parts which suits the following function. i. The layer which prevents the reflection of light. ii. The structure that alters the focal length of the lens iii. The region of distinct vision iv. The part which transmits the impulse to the brain. v. The outer most transparent layer in front of the eye. vi. The fluid present in the anterior part of the eye in front of the lens. 6. Given below is the diagram of the human ear. Study the same and answer the questions that follow. 1. Give the biological term for the part labeled as A. Ear ossicles 2. Name the part labeled as B and state its function. Eustachian tube-to equalize the air pressure on either side of the ear drum 3. Name the part labeled as C and state its function. Auditory nerve-its function is to send the impulse to the temporal lobe of the brain 4. Give the function of ear wax It prevents the entry of the dust particle into the ear. 7. Given below is the diagram depicting a defect of the human eye. Study the same and answer the questions that follow. 1. Identify the defect. Hypermetropia 2. Mention two reasons for the above defect. 1. The lens is the flattened 2. Eye ball is short from front to back. 3. State how the defect can be rectified. By using convex lens of proper focal length 4. Name the part of the eye responsible for maintaining the shape of the eyeball. Vitreous humor 8. The diagram given shows the structure of spinal cord depicting a simple reflex. Study the same and answer the questions that follows. 1. Name the parts labeled 1 to 5. 1. Sensory neuron, 2. Cell body 3. White mater 4. Cell body of the motor neuron, 5. Spinal nerve 2. What is the term given to the point of contact between the two nerve cells. Synapse 3. What is meant by simple reflex? It is an involuntary quick response to the stimulus. 4. How does the arrangement of nerve cells in the spinal cord differ from that in the brain? In spinal cord the white mater is outside and the grey matter is inside while in brain grey matter is outside and the white mater is inside. 5. 1. 1. 2. 3. 4. 5. 6. 7. 8. The given figure represents the human eye. Label the parts 1 to 8. Sclera, Choroid, Retina, Suspensory ligament, Lens, Conjunctiva, pupil Iris 2. State the function of sclera and ciliary muscles 1. Sclera protects the eye ball 2. Ciliary muscles changes the shape of the lens for viewing objects at different distances. 3. What is retina? Name the photosensitive cells present in the eye. 1. The photosensitive layer of the eye ball is called as retina. 2. It contains rod and cones. 4. What is visual purple? Rhodopsin pigment present in the rods. 5. What difference between yellow spot and blind spot? Yellow spot is the spot of best vision and blind spot is the region of no vision.
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