A level Biology - Cardiovascular system

Where is the heart beat initiated?

• right atrium

• right ventricle

• left atrium

• left ventricle

The graph shows the oxygen dissociation curves of haemoglobin from an adult sheep and a fetal sheep.

Which one of the following statements describes the difference in the behaviour of the two types of haemoglobin?

• Fetal haemoglobin has a higher oxygen affinity than adult haemoglobin.

• Adult haemoglobin has a higher oxygen affinity than fetal haemoglobin.

• Fetal haemoglobin cannot carry as much oxygen as adult haemoglobin.

• Adult haemoglobin cannot carry as much oxygen as fetal haemoglobin.

Which one of the following is found in the wall of both arteries and capillaries?

• connective tissue

• smooth muscle cells

• endothelial cells

• elastic fibres

From which part of the body has the blood come, if it is entering the heart of a human from the inferior vena cava?

• the abdomen

• the lungs

• the head

• the arms

Sphincter muscles are typically found in the walls of which vessels?

• arteries

• arterioles

• veins

• capillaries

Valves are typically found in which blood vessels?

• arteries

• arterioles

• veins

• capillaries

Fig. 7.1 shows the oxygen dissociation curves for a solution of oxyhaemoglobin, Curve P, and for mammalian whole blood, Curve Q.

R and S represent the oxygen tension (partial pressure) in the lungs and tissues respectively.

Whole blood (Curve Q) is physiologically more effective than a solution of oxyhaemoglobin (Curve P).

Which statement accounts for this?

• Blood can carry more oxygen than oxyhaemoglobin.

• Whole blood retains more oxygen at S than oxyhaemoglobin.

• Whole blood yields more oxygen at S than does oxyhaemoglobin.

• Whole blood has a greater affinity for oxygen than oxyhaemoglobin.

How is tissue fluid formed?

• Osmosis draws water out of capillaries.

• Facilitated diffusion causes water to leave capillaries.

• Active transport moves water out of capillaries.

• Hydrostatic pressure forces water out of capillaries.

Carbon dioxide is carried in the blood from tissues to lungs.

In what form is this carbon dioxide?

• carbaminohaemoglobin in erythrocytes

• carboxyhaemoglobin in erythrocytes

• carbonic acid dissolved in plasma

• hydrogen carbonate ions in plasma

In the chloride shift in blood in the tissues, where do Cl ^- ions diffuse?

• Into erythrocytes to maintain electrical neutrality.

• Out of erythrocytes to maintain electrical neutrality.

• Into erythrocytes to maintain pH.

• Out of erythrocytes to maintain pH.