The eye — return questions

1. state

State the stimulus that the receptors in (a) the eye and (b) the nose respond to.

(a) Eye

(b) Nose

2. state

State the function of (a) the lens and (b) the retina.

(a) Lens

(b) Retina

3. identify

Which place on the retina has no light receptors?

Circle one answer.

• Where the image of what you look at falls.
• At the front edge, closest to the iris.
• Where the optic nerve leaves the eye.
• Nowhere: the whole retina has receptors.

4. state / explain

In the experiment, you turned the lamp setting down from 5 (bright) to 1 (dim). (a) State what happened to the pupil diameter. (b) Explain how this change helps the eye to see.

(a) Pupil diameter

(b) How it helps

5. identify / state

Supplement: identify the two sets of muscles in the iris, and state what happens to the pupil when each set contracts.

(a) First set and its effect

(b) Second set and its effect

6. identify

What is the stimulus in the pupil reflex?

Circle one answer.

• The contraction of the iris muscles.
• A change in light intensity.
• A change in the distance of the object.
• Impulses in the optic nerve.

7. state

Supplement: you look at a distant object. State what happens to (a) the ciliary muscles, (b) the suspensory ligaments and (c) the lens.

(a) Ciliary muscles

(b) Suspensory ligaments

(c) Lens

8. state / explain

Supplement: a tiny sample of a human retina is found to contain no rods at all. (a) State the two places on the retina it could have come from. (b) Explain how counting its cones would tell you which place it came from.

(a) The two places

(b) How the cones tell them apart

9. compare

Supplement: state two differences between the functions of rods and cones.

10. state

Supplement: state (a) where the fovea is and (b) its function.

(a) Where

(b) Function