MCQ Quiz

Q21. The immediate effect of light on photoreceptors is:

Depolarization

Hyperpolarization

Action potential generation

Neurotransmitter release

Explanation:
Light closes Na⁺ channels causing hyperpolarization.

Q22. In darkness, photoreceptors are:

Hyperpolarized

Silent

Depolarized and releasing inhibitory neurotransmitter

Releasing excitatory neurotransmitter

Explanation:
Dark current keeps photoreceptors depolarized.

Q23. Closure of sodium channels during phototransduction is due to:

↓ cGMP

↑ cGMP

↑ calcium

↓ phosphodiesterase

Explanation:
Light activates PDE → ↓ cGMP → Na⁺ channel closure.

Q24. Vitamin A deficiency leads to:

Color blindness

Glaucoma

Macular degeneration

Night blindness

Explanation:
Vitamin A is essential for rhodopsin regeneration.

Q25. Complete dark adaptation of rods takes approximately:

5–10 minutes

30–50 minutes

1–2 minutes

Several hours

Explanation:
Rods adapt slower but reach higher sensitivity.

Q26. Y ganglion cells are specialized for:

Rapid movement detection

Color discrimination

Fine visual acuity

Night vision only

Explanation:
Y cells transmit fast, black-and-white motion information.

Q27. Fibers from the nasal retina:

Remain ipsilateral

Terminate in superior colliculus only

Decussate at optic chiasm

Terminate in cerebellum

Explanation:
Nasal retinal fibers cross at the optic chiasm.

Q28. Lesion at the optic chiasm causes:

Homonymous hemianopia

Quadrantanopia

Central scotoma

Bitemporal hemianopia

Explanation:
Crossing nasal fibers carry temporal visual fields.

Q29. The primary relay station for vision is the:

Superior colliculus

Lateral geniculate body

Pretectal nucleus

Visual cortex

Explanation:
LGB controls and relays signals to visual cortex.

Q30. Magnocellular layers of LGB receive input from:

Y ganglion cells

X ganglion cells

W ganglion cells

Amacrine cells

Explanation:
Magnocellular layers (1–2) process motion & black-white vision.

Q31. Parvocellular layers of LGB are responsible for:

Motion detection

Night vision

Color and fine detail

Reflex eye movement

Explanation:
Layers 3–6 process color and high acuity.

Q32. Primary visual cortex corresponds to:

Area 18

Area 17

Area 19

Area 6

Explanation:
Area 17 lies in the calcarine fissure.

Q33. The fourth layer of visual cortex primarily receives input from:

Association cortex

Superior colliculus

Optic nerve

Lateral geniculate body

Explanation:
Layer IV is the main thalamocortical input layer.

Q34. The dorsal visual stream answers:

Where is the object?

What is the object?

What color is it?

Is it familiar?

Explanation:
Dorsal stream processes motion and spatial location.

Q35. The ventral visual stream is mainly concerned with:

Motion

Depth

Object recognition

Eye movement

Explanation:
Ventral stream is the “what” pathway.

Q36. Damage to inferior temporal cortex causes inability to:

See motion

See color

See light

Recognize faces

Explanation:
IT cortex is critical for face recognition.

Q37. The suprachiasmatic nucleus receives fibers mainly for:

Visual perception

Circadian rhythm control

Pupillary reflex

Eye movements

Explanation:
SCN is the biological clock.

Q38. Pretectal nucleus is essential for:

Pupillary light reflex

Visual acuity

Color vision

Depth perception

Explanation:
Pretectal nucleus mediates pupillary reflexes.

Q39. Superior colliculus is involved in:

Color discrimination

Form vision

Rapid eye movements

Visual memory

Explanation:
Superior colliculus controls rapid, reflex eye movements.

Q40. Contralateral homonymous hemianopia results from lesion of: