Q.1. Which of the following statements is correct? (2019)
(a) Cornea consists of dense matrix of collagen and is the most sensitive portion of the eye.
(b) Cornea is an external, transparent and protective proteinacious covering of the eye-ball.
(c) Cornea consists of dense connective tissue of elastin and can repair itself.
(d) Cornea is convex, transparent layer which is highly vascularised.
Q.2. Which part of the brain is responsible for thermoregulation? (2019)
(a) Medulla oblongata
(d) Corpus callosum
Hypothalamus is thermoregulatory centre. Hence it is called “thermostat” of the body. It keeps body temperature at roughly 37°C by means of a complex thermostat system.
Q.3. Which of the following statements is not correct? (2019)
(a) An action potential in an axon does not move backward because the segment behind is in a refractory phase.
(b) Depolarisation of hair cells of cochlea results in the opening of the mechanically gated potassium-ion channels.
(c) Rods are very sensitive and contribute to daylight vision.
(d) In the knee-jerk reflex, stimulus is the stretching of muscle and response is its contraction.
Cones contribute to daylight vision whereas rods contribute to twilight vision.
Q.4. Which of the following receptors are specifically responsible for maintenance of balance of body and posture? (2019)
(a) Basilar membrane and otoliths
(b) Hair cells and organ of corti
(c) Tectorial membrane and macula
(d) Crista ampul laris and macula
Q.5. Nissl’s bodies are mainly composed of (2018)
(a) Proteins and lipids
(b) DNA and RNA
(c) Nucleic acids and SER
(d) Free ribosomes and RER.
Nissl’s bodies, also know n as NissPs granules are irregular masses of rough endoplasmic reticulum (RER) with numerous as well as free ribosomes and polysomes, found in cell body or cyton of a neuron. These probably synthesise protein for the nerve cell.
Q.6. Which of the following structures or regions is incorrectly paired with its functions? (2018)
| (a) Medulla oblongata||Controls respiration and cardiovascular reflexes|
|(b) Limbic system||Consists of fibre tracts that interconnect different regions of brain controls movement|
|(c) Hypothalamus||Production of releasing hormones and regulation of temperature, hunger and thirst|
|(d) Corpus callosum||Band of fibers connecting left and right cerebral hemispheres|
Certain components of the cerebrum and diencephalon constitute the limbic system. It is sometimes called the emotional brain because it controls emotional behaviour expressed in the form of joy, sorrow, fear, fight, friendship, liking and disliking. It also controls food habits and sex behaviours necessary for survival of the individual.
Q.7. The transparent lens in the human eye is held in its place by (2018)
(a) Ligaments attached to the ciliary body
(b) Ligaments attached to the iris
(c) Smooth muscles attached to the iris
(d) Smooth muscles attached to the ciliary body.
Lens is a transparent, biconvex structure that bends light waves as they pass through its surface. In the human eye, the lens is held in its place by suspensory ligament attached to the ciliary body.
Q.8. Myelin sheath is produced by (2017)
(a) Astrocytes and Schwann cells
(b) Oligodendrocytes and osteoclasts
(c) Osteoclasts and astrocytes
(d) Schwann cells and oligodendrocytes.
Schwann cells and oligodendrocytes form myelin sheath around the axon. Myelin sheath serves as an insulating layer, preventing loss of energy of the nerve impulse during its passage along the fibre.
Q.9. Receptor sites for neurotransmitters are present on (2017)
(a) Pre-synaptic membrane
(b) Tips of axons
(c) Post-synaptic membrane
(d) Membranes of synaptic vesicles.
Neurotransmitter is a chemical substance responsible for transmission of nerve impulse across synapse. It is released by synaptic vesicle into the synaptic cleft. Neurotransmitter binds with protein receptor molecule present on post synaptic membrane causing its depolarisation and generation of action potential.
Q.10. Good vision depends on adequate intake of carotene rich food.
Select the best option from the following statements. (2017)
(1) Vitamin A derivatives are formed from carotene.
(2) The photopigments are embedded in the membrane discs of the inner segment.
(3) Retinal is a derivative of vitamin A.
(4) Retinal is a light absorbing part of all the visual photopigments.
(a) (1), (3) and (4)
(b) (1) and (3)
(c) (2), (3) and (4)
(d) (1) and (2)
Q.11. Choose the correct statement. (2016)
(a) Nociceptors respond to changes in pressure.
(b) Meissner's corpuscles are thermoreceptors.
(c) Photoreceptors in the human eye are depolarised during darkness and become hyperpolarised in response to the light stimulus.
(d) Receptors do not produce graded potentials.
Photoreceptors in human eye are unique because they are only type of sensory cells that are relatively depolarised (about - 35mV) when it is at rest (i.e., in the dark), and hyperpolarised (to about - 70mV) in response to adequate light stimulus. Nociceptors respond to potentially damaging stimuli that result in pain. Meissner’s corpuscles are a type of mechanoreceptor, responsible for touch sensitivity. Receptors generally produce graded potentials called receptor potentials.
Q.12. Photosensitive compound in human eye is made up of (2016)
(a) Guanosine and Retinol
(b) Opsin and Retinal
(c) Opsin and Retinol
(d) Transducin and Retinene
Retinal is also known as retinaldehyde. It was originally called retinene, and renamed afterwards it was discovered to be vitamin A aldehyde. Retinal is one of the many forms of vitamin A (the number of which varies from species to species). Retinal is a polyene chromophore, bound to proteins called opsins, and is the chemical basis of animal vision.
Q.13. A gymnast is able to balance his body upside down even in the total darkness because of: (2015)
(a) Vestibular apparatus
(b) Tectorial membrane
(c) Organ of corti
Vestibular apparatus has specific receptors called crista and macula to maintain the balance and posture of body
Q.14. Which of the following regions of the brain is incorrectly paired with its function? (2015)
(a) Cerebellum – language comprehension
(b) Corpus callosum – communication between the left and right cerebral cortices
(c) Cerebrum – calculation and contemplation
(d) Medulla oblongata – homeostatic control
Cerebellum maintains the balance and body posture. It is not concerned with logical part.
Q.15. In mammalian eye, the 'fovea' is the center of the visual field, where: (2015)
(a) The optic nerve leaves the eye
(b) Only rods are present
(c) More rods than cones are found
(d) High density of cones occur, but has no rods.
Fovea centralis is the most sensitive part of retina. It has high density of cones, but rods are not found.
Q.16. Destruction of the anterior horn cell of the spinal cord would result in loss of: (2015)
(a) Voluntary motor impulses
(b) Commissural impulses
(c) Integrating impulses
(d) Sensory impulses
In poliomyelitis, anterior horn cells of spinal cord are destructed which causes loss of motor activities of limbs.
Q.17. Stimulation of a muscle fiber by a motor neuron occurs at: (2014)
(a) The neuromuscular junction
(b) The transverse tubules
(c) The myofibril
(d) The sacroplasmic reticulum
The neuromuscular junction connects the nervous system to the muscular system via synapses between efferent nerve fibres and muscle fibres.
Q.18. Injury localized to the hypothalamus would most likely disrupt: (2014)
(a) Short - term memory.
(b) Co-ordination during locomotion.
(c) Executive functions, such as decision making.
(d) Regulation of body temperature.
The hypothalamus is a highly complex structure in the brain that regulates many important brain chemicals. The hypothalamus is responsible for hormone production. The hormones produced by this area govern body temperature, thirst, hunger, sleep, circadian rhythm, moods, sex drive, and the release of other hormones in the body. This area of the brain controls the pituitary gland and other glands in the body.
Q.19. Which one of the following statements is not correct? (2014)
(a) Retinal is the light absorbing portion of visual photo pigments.
(b) In retina the rods have the photopigment rhodopsin while cones have three different photopigments.
(c) Retinal is a derivative of Vitamin C.
(d) Rhodopsin is the purplish red protein present in rods only.
Retinal is a derivative of vitamin A. Retinal is a polyene chromophore, and bound to proteins called opsins, is the chemical basis of animal vision. Bound to proteins called type 1 rhodopsins, retinal allows certain microorganisms to convert light into metabolic energy.