Some babies are born with a hole between the right and left atria.

These babies are found to have an increased number of red blood cells.

What is the reason for this increase in red blood cells in these babies?

• Blood is pumped faster, which causes more blood to circulate in the heart.

• More blood is needed in the heart because the pressure is lower

• Their haemoglobin has a higher affinity for oxygen.

• There is a lower oxygen concentration in the body of the newborn baby.

An increase in carbon dioxide in human blood shifts the oxyhaemoglobin dissociation curve to the right.

What is the explanation for this effect?

• An increase in carbon dioxide concentration increases the breathing rate.

• Carbon dioxide is more soluble than oxygen and displaces it.

• Diffusion of carbon dioxide between the alveoli and the blood is more rapid.

• Increasing the H+ concentration decreases haemoglobin affinity for oxygen.

‘Heart block’ is a disease which can result in a lower than normal heart rate. A doctor treating a person with 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 parts may not be functioning correctly in the person with heart block?

1 atrioventricular node (AVN)

2 Purkyne tissue

3 sinoatrial node (SAN)

• 1 and 2

• 1 and 3

• 2 and 3

• 3 only

What will happen as a result of the blood pressure in the right ventricle becoming higher than the blood pressure in the right atrium?

• The semilunar valve in the aorta will close.

• The semilunar valve in the pulmonary artery will close.

• The left atrioventricular valve will close.

• The right atrioventricular valve will close.

What explains how the maximum volume of oxygen is taken up as blood passes through the capillaries of the lungs?

• Each haemoglobin molecule can temporarily bind to four oxygen atoms. B The dissociation of carbon dioxide from carboxyhaemoglobin allows more haemoglobin to be available for binding oxygen. C The binding of the first oxygen molecule to haemoglobin decreases the affinity of haemoglobin for binding other oxygen molecules. D Oxyhaemoglobin formation increases the ability of red blood cells to transport oxygen.

• The dissociation of carbon dioxide from carboxyhaemoglobin allows more haemoglobin to be available for binding oxygen.

• The binding of the first oxygen molecule to haemoglobin decreases the affinity of haemoglobin for binding other oxygen molecules.

• Oxyhaemoglobin formation increases the ability of red blood cells to transport oxygen.

The diagram shows a cross-section through a mammalian heart.

Which chambers of the heart are represented by G and H?

• A

• B

• C

• D

The bar charts show the quantity of endothelial tissue, elastic tissue and muscle tissue in the walls of three blood vessels, P, Q and R.

Which row correctly identifies the three blood vessels?

• A

• B

• C

• D

Why do the ventricles have thicker walls with more muscle than the atria?

• the atria require more pressure to pump blood

• the ventricles require less pressure to pump blood

• the ventricles require more pressure to pump blood a long distance

• the atria require more pressure to pump blood a short distance

Which of the following is not a function of blood?

• transporting waste for excretion

• producing hormones

• transporting oxygen and carbon dioxide

• transporting nutrients from digestion

What is the main difference between lymph and tissue fluid?

• lymph has more red blood cells

• lymph has fewer fatty acids

• lymph has less oxygen and nutrients

• lymph has fewer white blood cells