51) When viewing an object in close distance, the lens should be more

A) rounded.

B) flattened.

C) convex.

D) lateral.

E) medial.

52) A blind spot in the retina occurs

A) at the fovea.

B) where ganglion cells synapse with bipolar cells.

C) at the optic disc.

D) where rod cells are clustered to form the macula.

E) where amacrine cells are located.

53) The abducens nerve innervates which extrinsic eye muscle?

A) superior oblique

B) medial rectus

C) inferior oblique

D) superior rectus

E) lateral rectus

54) Treatment of a cataract usually involves removal of the

A) cornea.

B) iris.

C) lens.

D) sclera.

E) vitreous humor.

55) The highest concentration of cones is in the ________.

A) fibrous layer

B) blind spot

C) choroid

D) optic disc

E) fovea centralis

56) A person suffering from ________ can see distant objects more clearly than those that are close.

A) myopia

B) hyperopia

C) glaucoma

D) emmetropia

E) cataracts

57) Which statement is correct?

A) For distant vision, the ciliary muscle is relaxed and the lens is rounded.

B) For close vision, the ciliary muscle is relaxed and the lens is flattened.

C) For distant vision, the ciliary muscle is contracted and the lens is flattened.

D) The closer the light source, the shorter the focal distance.

E) For close vision, the ciliary muscle is contracted and the lens is rounded.

58) There are three different types of cones, each one sensitive to a different color wavelength of light. These cones are designated

A) red, yellow, and blue.

B) red, blue, and green.

C) red, green, and yellow.

D) yellow, green, and blue.

E) red, yellow, and indigo.

59) The daily day/night cycle known as a circadian rhythm involves the

A) inferior colliculi.

B) cerebellum.

C) pituitary gland.

D) medulla oblongata.

E) pineal gland.

60) The photoreceptors of the retina are called ________.

A) bipolar cells

B) horizontal cells

C) amacrine cells

D) ganglion cells

E) rods and cones