Question 1

Which of the following cell types in the retina have axon potentials?

Accepted Answer

A) Ganglion cells 
B) Amacrine cells 
C) Bipolar cells 
D) Horizontal cells A

Question 2

Under low or reduced light conditions, which of the following is responsible for the inward-directed sodium current in the outer segments of the photoreceptors?

Accepted Answer

A) Metarhodopsin II 
B) cGMP 
C) cis-retinal 
D) cAMP B

Question 3

Which of the following best describes the central fovea of the eye?

Accepted Answer

A) Cones only, highest visual acuity 
B) Cones only, lowest visual acuity 
C) Rods only, highest visual acuity 
D) Rods only, lowest visual acuity A

Question 4

Which of the following substances is responsible for activation of transducin during photoreception?

Accepted Answer

A) cGMP 
B) All-trans-retinal 
C) Rhodopsin 
D) Metarhodopsin II

Question 5

During photoreception all of the following increase except:

Accepted Answer

A) cGMP phosphodiesterase 
B) Transducin 
C) Metarhodopsin II 
D) Sodium influx into the outer segment of the rod

Question 6

Visual acuity is highest at the fovea centralis partly because each cone cell synapses with multiple ganglion cells in the fovea centralis.

Accepted Answer

A) Both the statement and the reason are correct and related. 
B) Both the statement and the reason are correct but not related. 
C) The statement is correct but the reason is not. 
D) The statement is not correct, but the reason is correct. 
E) Neither the statement nor the reason is correct.

Question 7

Males have a higher incidence of color blindness compared with females because of a genetic disorder passed along by which of the following?

Accepted Answer

A) X and Y chromosome 
B) X chromosome only 
C) X or Y chromosome 
D) Y chromosome only

Question 8

In the retina, the activation of adjacent rods and cones is prevented by the phenomenon of lateral inhibition. Which cell type is thought to be responsible for this process?

Accepted Answer

A) Bipolar cells 
B) Horizontal cells 
C) Ganglion cells 
D) Amacrine cells

Question 9

Rhodopsin decomposes on exposure to light, causing which of the following in rods of the retina?

Accepted Answer

A) Depolarization, decreased sodium conductance 
B) Depolarization, increased sodium conductance 
C) Hyperpolarization, decreased sodium conductance 
D) Hyperpolarization, increased sodium conductance

Question 10

Which of the following best describes cones of the retina?

Accepted Answer

A) Black and white 
B) Blue, green, violet 
C) Blue, yellow, orange 
D) Red, blue, green 
E) Red, blue, yellow

Question 11

Which of the following factors has a direct action to control sodium channel gating in rods of the retina?

Accepted Answer

A) Acetylcholine 
B) Cyclic adenosine monophosphate 
C) Cyclic guanosine monophosphate 
D) Norepinephrine 
E) Transducin

Question 12

Which of the following vitamins is essential for preventing night blindness?

Accepted Answer

A) A 
B) B 
C) C 
D) D 
E) E

Question 13

Which area of the retina is responsible for the greatest visual acuity in humans?

Accepted Answer

A) Fovea 
B) Optic disc 
C) Pigment layer 
D) Central fovea

Question 14

A 45-year-old woman with a vitamin A deficiency is most likely to have increased levels of which of the following substances in rods of the retina?

Accepted Answer

A) Activated transducin 
B) Cyclic guanosine monophosphate 
C) Rhodopsin 
D) Scotopsin

Exam 51: The Eye: II Receptor and Neural Function of the Retina