Question 1

Which structure of the eye is primarily responsible for the greatest degree of light refraction as light enters the eye?

Accepted Answer

Cornea

Question 2

A patient complains of blurry vision when looking at distant objects, but can see nearby objects clearly. Which condition is most likely present, and what type of lens would correct it?

Accepted Answer

Myopia; concave lens

Question 3

Which layer of the eyeball contains the photoreceptors responsible for detecting light?

Accepted Answer

Neural layer (retina)

Question 4

What is the main difference between rods and cones in the retina?

Accepted Answer

Rods are sensitive to low light and do not detect color; cones function best in bright light and detect color.

Question 5

During the process of accommodation for near vision, which of the following occurs?

Accepted Answer

Ciliary body contracts, decreasing tension on suspensory ligaments and rounding the lens.

Question 6

Which equation best describes the relationship between the focal length $f$, the object distance $d_o$, and the image distance $d_i$ in the eye's lens system?

Accepted Answer

$\frac{1}{f} = \frac{1}{d_o} + \frac{1}{d_i}$

Question 7

Which of the following best explains why the 'blind spot' in the retina is not usually noticed in daily life?

Accepted Answer

The brain fills in missing information based on surrounding images.

Question 8

A 60-year-old patient has difficulty focusing on close objects, with a near point of accommodation at 20 inches. What is the most likely diagnosis?

Accepted Answer

Presbyopia

Question 9

Which of the following is TRUE regarding the physiology of photoreceptors in the dark?

Accepted Answer

Na$^+$ channels are open due to cGMP, causing depolarization.

Question 10

Which pigment is found in rods and is essential for low-light vision?

Accepted Answer

Rhodopsin

Question 11

Which of the following best describes the visual pathway from the retina to the brain?

Accepted Answer

Retinal ganglion cell axons form the optic nerve, which transmits signals to the thalamus and then to the primary visual cortex.

Question 12

Which of the following conditions is caused by irregular curvature of the lens or cornea, resulting in uneven refraction of light?

Accepted Answer

Astigmatism

Question 13

Which of the following statements about cones is correct?

Accepted Answer

Cones contain photopsin pigments and are responsible for color vision.

Question 14

Which process occurs when light strikes rhodopsin in a rod cell?

Accepted Answer

Retinal changes from cis to trans form, activating transducin and phosphodiesterase (PDE).

Question 15

Which of the following is a function of the lacrimal apparatus?

Accepted Answer

Produces tears to lubricate and wash away debris from the eye

Question 16

Which equation best represents the change in membrane potential ($V_m$) of a photoreceptor cell when Na$^+$ channels close in response to light?

Accepted Answer

$V_m$ becomes more negative (hyperpolarizes)

Question 17

Which accessory structure of the eye is responsible for distributing tears and protecting the eye during blinking?

Accepted Answer

Palpebrae (eyelids)

Question 18

Which of the following best describes the role of horizontal and amacrine cells in the retina?

Accepted Answer

They alter sensitivity and increase contrast of visual images.

Question 19

Which of the following is TRUE regarding the flow of aqueous humor in the eye?

Accepted Answer

It flows from the posterior chamber to the anterior chamber and drains at the scleral venous sinus.

Question 20

Which of the following is a correct comparison between general and special senses?

Accepted Answer

General senses use receptive endings of sensory neurons; special senses use specialized receptor cells.

Vision: Anatomy, Physiology, and Sensory Pathways 13

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