Myelin sheath is produced by
1. Schwann cells and Oligodendrocytes
2. Astrocytes and Schwann cells
3. Oligodendrocytes and Osteoclasts
4. Osteoclasts and Astrocytes

In mammalian eye, the 'fovea' is the center of the visual field where
1. high density of cones occur, but has no rods
2. the optic nerve leaves the eye
3. only rods are present
4. more rods than cones are found

Photosensitive compound in human eye is made up of
1. Opsin and Retinal
2. Opsin and Retinol
3. Transducin and Retinene
4. Guanosine and Retinol

The process by which the vertebrate eye changes optical power to maintain a clear image or focus on an object as its distance varies is known as:

1. adaptation
2. accommodation
3. amblyopia
4. visual acquity

Choose the correct statement:
1. Nociceptors respond to changes in pressure
2. Meissner’s corpuscles are thermoreceptors
3. Photoreceptors in the human eye are depolarised during darkness and become hyperpolarised in response to the stimulus
4. Receptors do not produce graded potentials

Receptor sites for neurotransmitters are present on
1.membranes of synaptic vesicles
2. pre-synaptic membrane
3. tips of axons
4. post-synaptic membrane

The pigment that gets oxidized/bleached/decomposed when exposed to light is:
1. retinol
2. retinoyl ester
3. rhodopsin
4. iodopsin

Good vision depends on adequate intake of carotene rich food.
Select the best option from the following statements:
I. Vitamin-A derivatives are formed from carotene.
I. The photo pigments are embedded in the membrane discs of the inner segment.
III. Retinal is a derivative of vitamin-A.
IV. Retinal is a light absorbing part of all the visual photo pigments.
1. (I) and (II)
2. (I), (III) and (IV)
3. (I) and (III)
4. (II), (III) and (IV)

Destruction of the anterior horn cells of the spinal cord would result in loss of
1. sensory impulses
2. voluntary motor impulses
3. commissural impulses
4. integrating impulses