TRANSPORT IN MAMMALS

Haemoglobin can bind to carbon dioxide, carbon monoxide and oxygen. Which statement about the binding sites of haemoglobin is correct?

• Carbon dioxide and carbon monoxide bind to one site, oxygen binds to a different site.

• Carbon dioxide and oxygen bind to one site, carbon monoxide binds to a different site.

• Carbon monoxide and oxygen bind to one site, carbon dioxide binds to a different site.

• Carbon monoxide, oxygen and carbon dioxide all bind to different sites.

The diagram shows the pressure changes in various structures of the left side of the heart during the cardiac cycle. At the end of which period, A, B, C or D, is the ventricle full of blood?

• A

• B

• C

• D

Which substances will displace oxygen from oxyhaemoglobin? 1 carbon dioxide 2 carbon monoxide 3 hydrogen carbonate ions 4 hydrogen ions.

• 1 and 2 only

• 1 and 4 only

• 2 and 3 only

• 2 and 4 only

Which reactions will be taking place in blood that is passing through active tissues?

• 1, 2, 3, and 4

• 1, 2 and 4 only

• 1, 3 and 4 only

• 2 and 3 only

During a cardiac cycle, the pressure in the right ventricle is lower than that in the right atrium and lower than that in the pulmonary artery. Which row is correct?

• A

• B

• C

• D

What correctly describes an event in the cardiac cycle that follows atrial systole?

• A wave of excitation passes through the sinoatrial node (SAN), before spreading down to the base of the septum

• Electrical impulses pass from the muscles of the atria to the muscles of the ventricles to cause ventricular systole.

• Electrical impulses pass through conducting fibres, which cause a delay before spreading to Purkyne tissue.

• The opening and closing of the semilunar valves occurs later than the opening and closing of the atrioventricular valves.

‘Heart block’ is a disease which can result in a lower than normal heart rate. A doctor treating a patient suffering from heart block found that electrical impulses were initiated as normal but were not correctly conducted to the ventricles, so the rate of ventricular contraction was slowed. Which may be functioning incorrectly in the patient?

• A

• B

• C

• D

What happens during ventricular systole in a mammalian heart?

• aortic pressure increases

• atrioventricular valves open

• semilunar valves close

• ventricular pressure decreases

Which substances could displace oxygen from oxyhaemoglobin?

• 1 and 2

• 1 and 4

• 2 and 3

• 2 and 4

Which features enable the aorta to withstand ventricular systole?

• collagen fibres and elastin fibres

• collagen fibres and smooth muscle

• elastin fibres and endothelium

• endothelium and smooth muscle