nervous system/coordination

Question 1

Some diseases cause changes in blink rate. Doctors do not often use blink rate to diagnose these diseases. Suggest reasons why

Answer 1

Would not know the patient’s / human’s normal blink rate so unable to make a comparison;

Blink rate could be affected by stress of seeing a doctor;

Many factors could affect blink rate so it would be difficult to tell if blink rate was due to illness

Question 2

The KDR plus allele codes for the sodium ion channels found in neurones.

When DDT binds to a sodium ion channel, the channel remains open all the time.
Use this information to suggest how DDT kills insects.

and

Suggest how the KDR minus allele gives resistance to DDT.

Answer 2

1. Nerone remain depolarized
2. so no action potential
3. mutation changes shape