5.2 The human nervous system

EasyMedium
12345678910111213141516171819202122232425262728293031323334353637
Question 4
Medium30%

Many human actions are reflexes.

a.

Which two of the following are examples of reflex actions?

  • Blinking when a fly flies close to your eye
  • Pulling away your foot after stepping on a sharp pin
  • Choosing to walk slower on a sunny day
  • Writing a letter to a friend
  • Jumping over a puddle on the street
[2]
b.

Figure 1 shows how the size of the pupil of the human eye can change by reflex action.

Figure 1: Two simplified diagrams of a human eye. Eye A shows a very small, constricted pupil at the center of the iris (labeled as Structure Q). Eye B shows a very large, dilated pupil at the center of the iris. An arrow points from Eye A to Eye B, indicating the transition from constricted to dilated.

Name one stimulus that would cause the pupil to change in size from AAA to BBB, as shown in Figure 1.

[1]
c.

Structure Q causes the change in size of the pupil.

Name structure Q.

[1]
d.

Describe how structure Q causes the change in the size of the pupil from AAA to BBB.

[1]
e.

Figure 2 shows some structures involved in the coordination of a reflex action.

Figure 2: A diagram of a reflex arc showing a cross-section of the spinal cord. Neurone X (the sensory neurone) travels from a receptor to the spinal cord. Inside the grey matter of the spinal cord, Neurone X connects via a synapse to Neurone Y (the relay neurone). Neurone Y connects via a synapse to Neurone Z (the motor neurone), which travels out of the spinal cord to connect to an effector (muscle).

Describe how the structures shown in Figure 2 help to coordinate a reflex action.

[6]

5.2 The human nervous system Questions

  1. GCSE
  2. /Biology
  3. /5.2 The human nervous system