Coordination, Response & Homeostasis (CIE IGCSE Biology: Co-ordinated Sciences (Double Award))

Define the term sensitivity.

Fig. 1 shows the reflex arc involved in a simple reflex action.

Fig. 1

On Fig. 1, use label lines to identify and name the three types of neurone shown. 

A reflex is an involuntary action.

Explain what is meant by the term involuntary action.

When a body senses danger, more adrenaline is secreted from the adrenal glands.

Describe two ways in which the hormone adrenaline affects the body in preparation for action.

This question is about neurones and reflex actions.

Choose words from the list to complete the sentences.

Each word may be used once, more than once, or not at all.

endocrine                      fast                           impulses

motor                       nervous                         receptor                       sensory

slow                        stimuli                         synapses

Neurones are cells that are part of the (i)............................................... system.

There are three types of neurone involved in a simple reflex action: a sensory neurone, a relay neurone and a (ii)............................................... neurone.

The nerves conduct electrical (iii)............................................... . These are transmitted from one neurone to the next at junctions called (iv)............................................... . 

A reflex action is automatic, co-ordinated and (v)............................................... .

Insulin is a hormone that regulates the concentration of glucose in the blood.

Describe what is meant by the term hormone.

Extended Tier Only

Person A and person B were monitored to see how well they could control their blood glucose concentration.

They did not eat or drink anything other than water for eight hours before the monitoring began. They then drank a glucose solution.

Blood samples were taken at 30-minute intervals.

The blood samples were tested for glucose concentration.

The results are shown in Fig. 1.

Fig. 1

Calculate the percentage increase in the blood glucose concentration in person A between 60 and 90 minutes.

Give your answer as a percentage and to the nearest whole number.

[3]

Using Fig. 1, compare the response of person A with the response of person B after the ingestion of glucose.

[3]

Using Fig. 1, explain the response of person B after 90 minutes.

[4]