Coordination and control – the nervous system

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Question 8
Medium

An ecologist is studying the visual reflexes of a mammal. During the study, the animal is moved from a brightly lit chamber into a dark observation enclosure.

Diagram A shows the animal's eye while inside the brightly lit chamber. Diagram B shows the animal's eye after it has been moved into the dark observation enclosure.

Two diagrams of an eye. Diagram A shows an eye with a very small, constricted pupil at the center of the iris. Diagram B shows the same eye but with a very large, dilated pupil occupying most of the iris.

a.

Explain why the pupil changes from Diagram A to Diagram B, and describe the mechanism that causes this change.

[3]
b.

The diagrams below show how light from a distant object is focused in the eyes of two different people, Person X and Person Y.

Two diagrams showing simplified horizontal cross-sections of human eyes. In the eye of Person X, the incoming light rays pass through the lens and focus at a point behind the retina. In the eye of Person Y, the incoming light rays pass through the lens and focus at a point in the middle of the eyeball, well in front of the retina.

Name the eye defect shown for each person.

  • Person X
  • Person Y
[2]
c.

Identify the type of corrective lens needed for each person and explain how these lenses work.

[2]

Coordination and control – the nervous system Questions

  1. GCSE
  2. /Biology
  3. /Coordination and control – the nervous system