Q1. The part of the brain concerned with muscular movements is
- 1) Cerebellum
- 2) Thalamus
- 3) Temporal lobe of cerebrum
- 4) Hippocampus
Solution
The cerebellum controls rapid muscular activities such as walking, running, typing, jogging etc.
Q2. The decoding and interpretation of visual information are carried by the
- 1) Frontal lobe
- 2) Cerebellum
- 3) Parietal lobe
- 4) Temporal lobe
- 5) Occipital lobe
Solution
The cerebral hemisphere is divided into four lobes – anterior frontal lobe, middle parietal lobe, posterior occipital lobe and lateral temporal lobe. The decoding and interpretation of visual information, shape and colour are carried by the occipital lobe.
Q3. The purplish red pigment rhodopsin contained in the rod type of photoreceptor cells of the human eye is a derivative of
- 1) Vitamin C
- 2) Vitamin B1
- 3) Vitamin D
- 4) Vitamin A
Solution
Rhodopsin, a visual purple pigment, is a derivative of vitamin A.
Q4. Which part of the brain controls intellectual ability?
- 1) Occipital lobe
- 2) Parietal lobe
- 3) Temporal lobe
- 4) Frontal lobe
Solution
In the frontal lobe of the cerebral hemisphere, thoughts and actions are monitored and creative ideas occur, so it controls all intellectual ability.
Q5. Which part of the nervous system controls the reflex activity of the body?
- 1) Pons
- 2) Vermis
- 3) Corpus callosum
- 4) Spinal cord
Solution
The spinal cord controls the reflex activity of the body as it is a spontaneous automatic response to a stimulus. So, it reduces the work load of the brain.
Q6. The Nissl’s granules of nerve cell are made up of
- 1) RNA
- 2) DNA
- 3) ribosomes
- 4) protein
Solution
Nissl’s granules are the groups of ribosomes and rough endoplasmic reticulum. They are involved in synthesis of proteins.
Q7. The myelin sheath is derived from
- 1) Neuroglial cells
- 2) All of the above
- 3) Schwann cells
- 4) Nerve cells
Solution
In myelinated nerve fibres, the myelin sheath is derived from Schwann cells. It is present around the axon.
Q8. Chemicals which are released at the synaptic junction are called
- 1) Cerebrospinal fluid
- 2) Lymph
- 3) Hormones
- 4) Neurotransmitters
Solution
Neurotransmitters are the chemicals released from a presynaptic neuron which interact with specific receptor sites of a postsynaptic neuron.
Q9. Which one of the following does not act as a neurotransmitter?
- 1) Norepinephrine
- 2) Epinephrine
- 3) Cortisone
- 4) Acetylcholine
Solution
Cortisone is a hormone released by the adrenal glands.
Q10. The thermoregulatory centre in the body of a homeothermal animal and man is found in the
- 1) Cerebrum
- 2) Cerebellum
- 3) Hypothalamus
- 4) Medulla oblongata
Solution
The thermoregulatory centre is found in the hypothalamus of a homeothermal animal and man. It maintains homeostasis, i.e. it regulates the temperature of the body.
Q11. The human hindbrain comprises three parts, one of which is the
- 1) Hypothalamus
- 2) Corpus callosum
- 3) Cerebellum
- 4) Spinal cord
Solution
Cerebellum, pons and medulla oblongata are the three parts of the hindbrain.
Q12. Name the membrane present above the hair cells in the cochlea.
Solution
Tectorial membrane
Q13. State the two main parts of the human neural system.
Solution
Two main parts of the human neural system are Central Neural System (CNS) Peripheral Neural System (PNS)
Q14. The satiety centre of the brain is present in the
- 1) Cerebellum
- 2) Hypothalamus
- 3) Medulla oblongata
- 4) Cerebral hemisphere
Solution
The centre of satiety, i.e. the feeling of being satisfied, is present in the hypothalamus of the brain.
Q15. Cornea transplantation is outstandingly successful because
- 1) The technique involved is very simple
- 2) Cornea is not linked with blood vascular and immune systems
- 3) Cornea is easily available
- 4) Cornea is easy to preserve
Solution
Cornea is non-vascular. So, its transplantation is successful.
Q16. The receptor absent in the tongue is
- 1) Thermoreceptor
- 2) Photoreceptor
- 3) None of the above
- 4) Gustatoreceptor
Solution
Thermoreceptors (for temperature) and gustatoreceptors (for taste) are present in the tongue. Photoreceptors (for light) are present in the eye but absent in the tongue.
Q17. Name the structures which constitute the vestibular apparatus.
Solution
Semicircular canals and the otolith organ constitute the vestibular apparatus.
Q18. Explain the structure of the cochlea.
Solution
The cochlea is a spiral structure present in the inner ear. Reissner’s membrane and the basilar membrane divide the bony labyrinth into the scala vestibuli and scala tympani which are filled with perilymph. The scala media is filled with endolymph. The organ of Corti is the sensory structure present in the cochlea. It is located on the basilar membrane and contains sensory hair cells which act as auditory receptors. These hair cells are present in rows, and their apical parts bear stereo cilia. A tectorial membrane which is thin is present above the rows of sensory hair cells.
Q19. State the significance of the cone cells.
Solution
Cone cells are responsible for colour vision and photopic vision.
Q20. Name the two membranes of cochlea.
Solution
The two membranes of the cochlea are Reissner’s and basilar membranes.
Q21. Protein found in the eye lens is
- 1) Collagen
- 2) Crystallin
- 3) Rhodopsin
- 4) Opsin
Solution
Crystallin is a water-soluble protein present in the eye lens and cornea of the eye.
Q22. Corpora striata occur in
- 1) Diencephalon
- 2) Medulla
- 3) Cerebellum
- 4) Cerebrum
Solution
Corpora striata is present in the ventrolateral walls of the cerebral hemisphere.
Q23. Which of the cells are phagocytic as well as scavengers?
- 1) Microglia
- 2) Oligodendrocytes
- 3) Astrocytes
- 4) Neurons
Solution
Astrocytes, oligodendrocytes and microglia are three types of neuroglia. Astrocytes provide mechanical support to the neurons. Oligodendrocytes form myelin sheaths around the axon and microglia are phagocytic and scavengers. They engulf microbes and cellular debris.
Q24. Mark the vitamin present in Rhodopsin
- 1) Vitamin B
- 2) Vitamin D
- 3) Vitamin C
- 4) Vitamin A
Solution
Rhodopsin, a visual purple pigment, is a derivative of vitamin A.
Q25. Name the region in the eye where the photoreceptor cells are absent.
Solution
Blind spot
Q26. Name the structure which connects the middle ear and the pharynx. Also state its function.
Solution
The Eustachian tube connects the middle ear and the pharynx. It equalises the pressure on either side of the tympanic membrane or the ear drum.
Q27. Apart from the skull, name the covering which protects the brain. Write the names of the three layers which form this protective covering.
Solution
Cranial meninges. It is made of the following three layers: Outer dura mater Middle arachnoid Inner pia mater
Q28. The corpus callosum is formed between two
- 1) Kidneys
- 2) Ventricles
- 3) Cerebral hemispheres
- 4) Auricles
Solution
The corpus callosum is a large, curved tract of myelinated axons present at the bottom of the cerebral hemispheres.
Q29. State the function of the ear ossicles.
Solution
Ear ossicles increase the efficiency of the transmission of sound waves to the inner ear.
Q30. Cells of Schwann are associated with
- 1) Nervous tissue
- 2) Skeleton muscle
- 3) Connective tissue
- 4) Cartilage tissue
- 5) Cardiac muscle
Solution
The nervous tissue comprises a cell body (neuron) and neurites (dendrites and axon). In myelinated nerve fibres, Schwann cells form a myelin sheath around the axon.
Q31. Nissl’s granules are present in
- 1) WBC
- 2) RBC
- 3) Both 1 and 2 above
- 4) Nerve cells
Solution
Nissl’s granules are present in the cytoplasm of the cell body and the dendrites of the neuron.
Q32. The autonomic nervous system affects
- 1) None of the above
- 2) Internal organs
- 3) Reflex actions
- 4) Sensory organs
Solution
The autonomic nervous system controls the functioning of involuntary visceral organs. It is formed of the sympathetic nervous system and the parasympathetic nervous system. Both these systems are antagonistic to each other.
Q33. What is the organ of Corti?
Solution
The organ of Corti comprises the structures which are present on the basilar membrane of the cochlea and which bear auditory receptor hair cells.
Q34. In human brain, the corpus callosum connects
- 1) Bone and muscle
- 2) Two optic lobes
- 3) Two lobes of the pituitary gland
- 4) Two cerebral hemispheres
Solution
Two cerebral hemispheres are interconnected by a thick band of transverse nerve fibres called the corpus callosum.
Q35. Explain the mechanism of hearing in humans.
Solution
The pinna receives sound waves and directs them to the ear drum. The ear drum vibrates, and the vibrations are sent to the ear ossicles in the middle ear. The ear ossicles further transmit the vibrations to the oval window. The oval window passes the vibrations to the fluid of cochlea and causes vibrations in it.
The vibrations induce a ripple in the basilar membrane which bends the hair cells, which are pressed against the tectorial membrane. This causes the generation of the nerve impulse which is transmitted to the brain via the auditory nerve. The impulses are analysed, and the sound is recognised or heard.
Q36. Retina is most sensitive at
- 1) Fovea centralis
- 2) Periphery
- 3) Optic disc
- 4) Macula lutea
Solution
Macula lutea is a small area on the retina which lies opposite to the optical axis of the lens. It has a depression (the fovea centralis) in the middle. It is the area of most distinct day vision.
Q37. Describe the structure of a neuron.
Solution
Structure of neuron: Neuron is composed of cell body, dendrites and axon. The cell body contains cytoplasm. The cytoplasm consists of Nissl’s granules which are also present in dendrites. Dendrites are the short cytoplasmic branches given out by the cell body. Dendrites carry nerve impulse towards the cell body. Axon is the longest process given out by the cell body. In case of myelinated neuron, axon is covered with a myelinated sheath formed by Schwann cells. The gap between the two adjacent myelinated regions is called Node of Ranvier. The distal end of the axon called axon-terminal has bulb like structures call synaptic knobs which contain neurotransmitters.
Q38. In frog, “fenestra ovalis” is
- 1) the external opening of the tympanic cavity which is covered by the tympanic membrane
- 2) the air-filled cavity of the middle ear
- 3) the communication between the pharynx and the tympanic cavity
- 4) the opening in the auditory capsule which separates the middle ear from internal ear
Solution
“Fenestra ovalis” is an oval aperture through which tympanic cavity is connected with auditory capsule which houses the internal ear.
Q39. Name the photosensitive compounds present in the photopigments.
Solution
The photosensitive compounds present in the photopigments are Opsin – a protein and retinal (an aldehyde of vitamin A).
Q40. Colour perception in man is due to
- 1) Iodopsin pigment in cone cells
- 2) Rhodopsin pigment in cone cells
- 3) Iodopsin pigment in rod cells
- 4) Rhodopsin pigment in rod cells
Solution
Colour perception in man is due to iodopsin pigment in cone cells. In the retina, there are three types of cones which respond to red (erythropsin), green (chloropsin) and blue light (cyanopsin). Other colours are detected by simultaneous stimulation of more than one type of cone cell.
Q41. The electrical potential difference between outside and inside of a nerve axon before excitation is known as
- 1) Reaction potential
- 2) Activation potential
- 3) Resting potential
- 4) Spike potential
- 5) Action potential
Solution
The electrical potential difference across the resting plasma membrane is called a resting potential.
Q42. Name the two main divisions of the peripheral neural system.
Solution
Two main divisions of the peripheral neural system are Somatic neural system Autonomic neural system
Q43. Name the system which transmits impulses from the central neural system to the skeletal muscles.
Solution
Somatic neural system
Q44. Nissl’s granules are absent in the
- 1) Axon
- 2) Schwann cells
- 3) Cyton
- 4) Dendron
Solution
The cyton and dendrites contain Nissl’s granules. The axon does not have Nissl’s granules. In myelinated nerve fibres, Schwann cells form a myelin sheath around the axon.
Q45. Which part of the human brain is the largest?
- 1) Cerebellum
- 2) Cerebrum
- 3) Thalamus
- 4) Medulla
Solution
The cerebrum or cerebral hemisphere forms the largest part of the brain. It constitutes four-fifths of the brain weight.
Q46. Distinguish between axon and dendrite.
Solution
Axon Dendrite It is the longest fibre given out by the cell body of a neuron. Dendrites are small branches given out by the cell body. It carries impulses away from the cell body. It carries impulses towards the cell body.
Q47. Name the neurons which are found only during the embryonic stage.
Solution
Unipolar neurons
Q48. Where in the neural system are the multipolar neurons found?
Solution
Cerebral cortex
Q49. Which of the following is not involved in knee-jerk reflex?
- 1) Inter neurons
- 2) Motor neuron
- 3) Brain
- 4) Muscle spindle
Solution
The brain is not involved in the knee jerk reflex action as it is a spontaneous, automatic mechanical response to a stimulus without the will or thinking, of an organism.
Q50. In mammals, the brain centre which regulates body temperature is situated in the
- 1) Cerebellum
- 2) Cerebral lobe
- 3) Medulla oblongata
- 4) Hypothalamus
Solution
In mammals, the hypothalamus maintains homeostasis, i.e. it regulates body temperature.
Q51. Nodes of Ranvier are found in
- 1) Both 1 and 2 above
- 2) None of the above
- 3) Non-myelinated nerve fibres
- 4) Myelinated nerve fibres
Solution
Nodes of Ranvier are found in myelinated nerve fibres. These are the gaps between two adjacent myelin sheaths.
Q52. Name the ossicle to which the tympanic membrane is attached.
Solution
Malleus
Q53. Name the two parts of the bony labyrinth formed due to the cochlea.
Solution
Two parts of the bony labyrinth formed due to cochlea are Upper scala vestibule Lower scala tympani
Q54. One of the examples of the action of the autonomous nervous system is
- 1) Knee-jerk response
- 2) Swallowing of food
- 3) Pupillary reflex
- 4) Peristalsis of the intestines
Solution
Peristalsis of the intestines is an example of the autonomous nervous system as it is an involuntary activity of the body and is not according to the will of an organism.
Q55. Name the two photoreceptor cells present in the eye.
Solution
Rods and cones
Q56. Distinguish between the yellow spot and the blind spot.
Solution
Yellow Spot Blind Spot It is located lateral to the blind spot at the posterior pole of the eye. Blood vessels enter and the optic nerve leaves the eye at this spot. Cone cells are densely packed in this region. Photoreceptor cells, i.e. rods and cones, are absent. It is the region of sharpest vision. No vision is formed at the blind spot.
Q57. The area where the medullary sheath is absent in the nerve fibre is called
- 1) Schwann cells
- 2) Node of Ranvier
- 3) Nissl’s granules
- 4) Schwann nodes
Solution
The area where the medullary sheath is absent in the nerve fibre is called Node of Ranvier. These are the gaps between two adjacent myelin sheaths.
Q58. Telescopic vision is found in
- 1) Birds
- 2) Dog
- 3) Rabbit
- 4) Frog
Solution
Telescopic vision is found in birds, i.e. they have the ability to see distant objects clearly.
Q59. Acute vision is present in
- 1) Frog
- 2) Shark
- 3) Bat
- 4) Vulture
Solution
Acute vision is found in birds like vulture.
Q60. Name the gap which exists between pre-synaptic and post-synaptic neurons.
Solution
Synaptic cleft
Q61. How many pairs of spinal nerves are there in man?
- 1) 21
- 2) 31
- 3) 10
- 4) 15
Solution
There are 31 pairs of spinal nerves in man. These are classified into five groups: Cervical nerves – 8 pairs Thoracic nerves – 12 pairs Lumbar nerves – 5 pairs Sacral nerves – 5 pairs Coccygeal – 1 pair
Q62. Nerve cells do not divide because they do not have
- 1) Centrosome
- 2) Golgi body
- 3) Mitochondria
- 4) Nucleus
Solution
Nerve cells do not divide because they do not have a centrosome which helps in cell division by forming microtubule-organizing centres.
Q63. Which one of the following pairs of structures distinguishes a nerve cell from other types of cells?
- 1) Nucleus and mitochondria
- 2) Flagellum and medullary sheath
- 3) Perikaryon and dendrites
- 4) Vacuoles and fibres
Solution
Perikaryon and dendrites are present in a neuron. Perikaryon is a cytoplasm surrounding the nucleus. Dendrites are shorter, tapering and branched processes present in the cell body.
Q64. Name the granular bodies present in the cytoplasm of neurons.
Solution
Nissl’s granules
Q65. Iris is part of
- 1) Sclerotic
- 2) Choroid
- 3) Choroid and retina
- 4) Sclerotic and choroid
Solution
The iris consists of two layers—outer one in continuation with the choroid and inner one in continuation with the retina.
Q66. Name the region of the brain responsible for controlling body temperature.
Solution
Hypothalamus
Q67. The sequence of ear ossicles from the outside to inside is
- 1) Malleus ➜ stapes ➜ incus
- 2) Malleus ➜ incus ➜ stapes
- 3) Incus ➜ stapes ➜ malleus
- 4) Stapes ➜ incus ➜ malleus
Solution
The sequence of ear ossicles from outside to inside is Malleus ➜ incus ➜ stapes. Human ear bones or ossicles are incus, malleus and stapes. The outer ossicle is hammer-shaped and is called the malleus. The inner ossicle is stirrup-shaped and is called the stapes. The middle ossicle is anvil-shaped and is called the incus.
Q68. Name the two parts which form the outer ear.
Solution
Pinna and external auditory meatus form the outer or external ear.
Q69. One of the following examples of an action of the autonomic nervous system is
- 1) Knee jerk reflex
- 2) Swallowing of food
- 3) Pupillary reflex
- 4) Peristalsis of intestine
Solution
Peristalsis of intestine is an example of an action of the autonomic nervous system (ANS). ANS controls the function of visceral organs.
Q70. The sensitive pigmented layer of the eye is
- 1) Sclerotic
- 2) Retina
- 3) Iris
- 4) Cornea
Solution
The retina consists of a pigmented layer and a nervous tissue layer.
Q73. Name the two structures of the external ear and state their functions.
Solution
The two structures of the external ear are pinna and external auditory meatus. The pinna collects vibrations from the surroundings to generate sound. The external auditory meatus connects the pinna to the tympanic membrane and carries vibrations to the tympanic membrane.
Q72. What is the significance of the corpus callosum?
Solution
The corpus callosum connects the two cerebral hemispheres.
Q73. The mammalian brain differs from an amphibian brain in possessing
- 1) Cerebellum
- 2) Olfactory lobes
- 3) Corpus callosum
- 4) Hypothalamus
Solution
The mammalian brain has a corpus callosum which an amphibian brain does not possess. The corpus callosum is a large, curved tract of myelinated axons present at the bottom of the cerebral hemispheres.
Q74. The organ of Corti is a structure present in the
- 1) External ear
- 2) Middle ear
- 3) Semicircular canal
- 4) Cochlea
Solution
The organ of Corti is a structure present in the cochlea on its basilar membrane.
Q75. Name the pigment present in rod cells
Solution
Rhodopsin (visual purple)
Q76. Which of the following nerves is purely a motor nerve?
- 1) Vagus
- 2) Abducens
- 3) Trigeminal
- 4) Facial
Solution
Abducens is a motor nerve which controls the movement of the eyeball. Vagus, facial and trigeminal are mixed nerves.
Q77. Name the pigment which is the derivative of vitamin A.
Solution
Rhodopsin is the derivative of vitamin A.
Q78. Describe the mechanism of the formation of vision or image.
Solution
The light rays of the visible length are focused on the retina through the cornea and the lens. This light generates impulse in the rods and cones which contain photosensitive pigments composed of opsin and retinal. The light brings about the dissociation of retinal from opsin which brings about changes in the structure of opsin.
The change in the structure of opsin causes changes in membrane permeability which generates an action potential in the ganglion cells through the bipolar cells. Once the change in action potential is transmitted to the brain through the optic nerve, the brain sends the signals back to the eye forming the image of the retina.
Q79. Name the ossicle which is attached to the oval window.
Solution
Stapes is attached to the oval window.
Q80. Resting membrane potential is maintained by
- 1) Neurotransmitters
- 2) Hormones
- 3) None of the above
- 4) Ion pumps
Solution
The resting membrane potential is maintained by a sodium-potassium pump.
Q81. Name the middle layer of the cranial meninges.
Solution
Arachnoid
Q82. Describe the conduction of a nerve impulse through an axon.
Solution
At resting potential, the outer surface of the axon has a positive charge and the axoplasm has a negative charge. When a stimulus is received by the axon at resting potential, say at site A, the axonal membrane becomes freely permeable to Na+ ions.
This causes the rapid influx of Na+ ions which makes the outer surface of the membrane negatively charged, and the axoplasm is positively charged. Hence, the action potential is achieved.
The region ahead of the region, site B, which is the action potential will be still in the resting potential. Due to this, the current from site A flows to site B on the inner surface, and it flows from site B to site A on the outer surface. This results in the reverse of polarity, and hence, the action potential is generated at site B. This sequence is repeated along the length of the axon till the impulse reaches the axon terminal.
Q83. What are the two nerve fibres of PNS?
Solution
The two nerve fibres of PNS are Afferent fibres Efferent fibres
Q84. How is the action potential achieved by a neuron?
Solution
When a stimulus is received by the axon which is in the resting potential at certain site, say at site A, the axonal membrane becomes freely permeable to Na+ ions. This causes the rapid influx of Na+ ions which makes the outer surface of the membrane negatively charged, and the axoplasm is positively charged. The changes in the permeability of the membrane and influx of Na+ ions reverse the polarity of the membrane, and thus, the action potential achieved by the axon.
Q85. Where are the eyes located?
Solution
Eyes are located in socket-like structures called orbits of the skull.
Q86. The junction between the axon of one neuron and the dendrite of the next is called
- 1) Synapse
- 2) Junction point
- 3) Constant bridge
- 4) A joint
Solution
The junction between the axon of one neuron and the dendrite of the next is called a synapse. Depending on the nature of transfer of information, there are two types of synapses – chemical synapses and electrical synapses.
Q87. The supporting and nutritive cells found in the brain are
- 1) Ependymal cells
- 2) Oligodendrocytes
- 3) Astrocytes
- 4) Microglia
Solution
Astrocytes are star-shaped glial cells present in the brain. These are supporting and nutritive cells and also maintain ionic balance in the brain.
Q88. Name the region where the cone cells are densely packed.
Solution
At the fovea, the cone cells are densely packed.
Q89. Where is the vitreous chamber present?
Solution
The vitreous chamber is present between the lens and the retina.
Q90. The wax gland present in the ear canal is called
- 1) Prostate gland
- 2) Sebaceous gland/ceruminous gland
- 3) Cowper’s gland
- 4) Sweat gland
Solution
Wax glands present in the ear canal are called sebaceous glands or ceruminous glands. They secrete a brownish, semisolid, fatty substance called wax or cerumen.
Q91. What are synapses?
Solution
Synapses are the nerve junctions at which nerve impulses are transmitted from one neuron to another neuron.
Q92. Differentiate between rods and cones.
Solution
Rods Cones Rods are responsible for daylight and colour vision. Cones are responsible for the twilight or scotopic vision. Rods contain a purple-red pigment called rhodopsin. Cones contain a pigment called iodopsin.
Q93. Which cells are responsible for the twilight or scotopic vision?
Solution
Rods
Q94. What is reflex action? Explain the reflex pathway.
Solution
An involuntary response on stimulation of the peripheral nervous system which requires the involvement of a part of the central nervous system is called reflex action. The afferent neuron receives a signal from a sensory organ. It then transmits the impulse to the spinal cord via the dorsal root. The spinal cord sends the processed signal to the effectors through the efferent neuron forming a reflex arc.
Q95. Name the visible coloured portion of the eye.
Solution
Iris
Q96. Name the ions to which the axonal membrane is more permeable during the resting potential.
Solution
Potassium ions
Q97. What is the other name for the ear drum?
Solution
The other name for the ear drum is tympanic membrane.
Q98. Name the two structures of the brain which form the limbic system.
Solution
Amygdala and hippocampus
Q99. Write the significance of the autonomic neural system.
Solution
The autonomic neural system transmits nerve impulses from the central neural system to the involuntary organs and smooth muscles of the body.
Q100. Differentiate between myelinated nerve fibres and non-myelinated nerve fibres.
Solution
Myelinated Nerve Fibres Non-myelinated Nerve Fibres These nerve fibres have a myelinated sheath made of Schwann cells. These nerve fibres are enclosed by Schwann cells, but they do not form a myelinated sheath around the nerve fibres. They are found in spinal and cranial nerves. They are found in the autonomic and somatic nervous systems.
Q101. State the name of the anterior thick part of the choroid layer.
Solution
Ciliary body
Q102. Name the pigment spot present at the posterior pole of the eye.
Solution
Macula lutea
Q103. The pigment iodopsin is contained in
- 1) Horizontal cells
- 2) Amacrine cells
- 3) Cone cells
- 4) Rod cells
Solution
Cone cells contain a visual violet pigment called iodopsin which is sensitive to bright day light.
Q104. Name the region of the brain which analyses the image formed on the retina.
Solution
The visual cortex of the brain analyses the image formed on the retina.
Q105. Name the space between the cornea and the lens.
Solution
Aqueous chamber
Q106. Name the three ossicles present in the ear.
Solution
Three ossicles present in the ear are malleus, incus and stapes.
Q107. Name the ridge of the ampulla which is projected and contains hair cells.
Solution
Crista ampullaris
Q108. State the three types of neurons on the basis of number of axons and dendrites present. Also, state the number of axons and dendrites present and their location in the neural system.
Solution
The three types of neurons on the basis of number of axons and dendrites are Multi-polar neuron Bipolar neuron Unipolar neuron Multi-polar neuron: It has one axon and two or more dendrites. It is found in the cerebral cortex. Bipolar neuron:It has one axon and one dendrite. It is found in the retina of the eye. Unipolar neuron: It has a cell body with only one axon. It is found during embryonic development.
Q109. How many sodium ions move outwards per two potassium ions during the conduction of nerve impulse?
Solution
Three sodium ions
Q110. Explain the conduction of the nerve impulse at a chemical synapse.
Solution
Pre-synaptic and post-synaptic neurons are separated from each other by a synaptic cleft filled with a fluid. When the impulse reaches the axon terminal of the pre-synaptic neuron, it stimulates the movement of synaptic vesicles containing neurotransmitters towards the axon terminal to fuse with the plasma membrane. When synaptic vesicles fuse with the plasma membrane, they release neurotransmitters.
These neurotransmitters travel through the synaptic cleft and bind to the receptors present on the post-synaptic membrane. This binding opens the channels on the post-synaptic membrane which allows the entry of ions. The entry of ions into the post-synaptic neuron generates a new potential.
Q111. What is the function of the association areas?
Solution
Association areas are responsible for functions such as memory, communication and intersensory association.
Q112. Name the cells which form a myelinated sheath around a myelinated nerve fibre.
Solution
Schwann cells
Q113. Where is the endolymph present?
Solution
Endolymph is present in the membranous labyrinth and the scala media of cochlea.
Q114. The sense of smell is perceived by
- 1) Pituitary
- 2) Hypothalamus
- 3) Olfactory lobe
- 4) Cerebrum
Solution
The anterior part of the brain is formed by a pair of short club-shaped structures, the olfactory lobes. Olfactory lobes are concerned with the sense of smell.
Q115. Name the pigment present in the photopigments.
Solution
Opsin
Q116. Name the layer of cranial meninges which is in direct contact with the brain tissue.
Solution
Pia mater
Q117. Define coordination in living organisms. Why is it necessary? Give any one example.
Solution
Coordination is the process in which one or more tissues or organs interact and complement the function of each other to maintain the homeostasis of the body. During physical exercise, there is always increased energy demand. To fulfil this demand, the supply of oxygen to the cells in concern increases. To provide more oxygen, our respiration rate, heartbeat and blood flow increase.
Q118. State the significance of pinna.
Solution
Pinna collects vibrations from the surroundings to generate sound.
Q119. At the action potential, what charge is present on the inner surface of the axonal membrane?
Solution
Positive charge
Q120. Name the canal which passes through the midbrain.
Solution
Canal aqueduct
Q121. At the resting potential, the inner axonal membrane contains K+ ions and negatively charged proteins and the fluid outside the membrane contains Na+ ions. What would be the charge present on the outer surface of the membrane during the action potential?
Solution
Negative charge
Q122. Where are the non-myelinated neurons present in the neural system?
Solution
Autonomic and somatic neural systems
Q123. Differentiate between aqueous chamber and vitreous chamber.
Solution
Aqueous Chamber Vitreous Chamber It is the space between the cornea and the lens. It is the space between the lens and the retina. It is filled with a fluid called the aqueous humour. It is filled with the vitreous humour.
Q124. Name the three cells present in the retina of the eye.
Solution
Three cells present in the retina of the eye are ganglion cells, bipolar cells and photoreceptor cells.
Q125. Eyes are the most important sense organs in animals without which it would have been difficult to experience the beauty of life. Name the photoreceptor cells and their pigments present in the retina. Name the compounds present in the photopigments. State the functions of rods and cones. What values do you learn from questions (a) and (c)?
Solution
Cones and rods. Iodopsin is present in cone cells, and rhodopsin is present in rid cells. Opsin and retinal are present in photopigments. Rod cells are responsible for coloured and daylight vision, while cones are responsible for twilight vision. In team work, to achieve success in any task, synchronisation in the work of team members is of utmost importance.
Q126. Name the external layer of the eyeball.
Solution
Sclera
Q127. Which types of neurons are found in the retina of the eye?
Solution
Bipolar neurons
Q128. Name the fluid present outside the membranous labyrinth.
Solution
Perilymph
Q129. In which parts of the neural system are the myelinated nerve fibres found?
Solution
Spinal and cranial nerves
Q130. Colour blindness is due to a defect in
- 1) Cones
- 2) Rods
- 3) Rods and cones
- 4) Rhodopsin
Solution
Colour blindness is the inability to see colours. Lack of one or more types of cone cells causes colour blindness.
Q131. When is the sensation of white light produced?
Solution
When the cones responsible for different colours are stimulated equally, white light is produced.
Q132. Which layer of the eyeball contains more number of blood vessels?
Solution
Choroid layer