Name valve A and chamber B.

Valve A ______________

Chamber B ______________

Give two safety precautions that should be followed when dissecting a heart.

1

2

Explain how valve A in Figure 2 maintains a unidirectional flow of blood.

A research scientist investigated the effect of caffeine on heart rate in human volunteers.

The scientist divided volunteers into three groups. Each group was given the same volume of fluid.

• Each member of Group I was given a sports drink containing caffeine and sugar.

• Each member of Group J was given a sports drink containing caffeine and no sugar.

• Each member of Group K was given water.

The scientist recorded the volunteers' heart rate before the drink was given and for 120 minutes after the drink was given.

Her results can be seen in Figure 3.

Caffeine affects the autonomic nervous system.

Suggest how caffeine could account for the results of Group I in Figure 3 at 60 minutes.

Before taking the drink, the mean heart rate of Group J was 68 beats per minute.

Fifteen minutes after taking the drink, the mean volume of blood leaving the hearts of Group J was 4700 cm3 per minute.

Calculate the mean volume of blood leaving the heart at each beat fifteen minutes after taking the drink.

Answer = ______________ cm3

The increase seen in Group I could be due to the combination of caffeine and sugar.

Suggest one drink to be given to an additional group that should be investigated to find out if this is true.

Give a reason for your answer.

Group to be given ______________

Reason ______________