State the visible evidence in Fig. 5.1 that shows the cells inside the capillary are red blood cells.
Explain how the structure of the capillary wall is linked to its functions.
A rise in respiration causes the carbon dioxide concentration in the blood to increase and more oxygen to be released from red blood cells to tissues. Explain how a rise in carbon dioxide in the blood causes more oxygen to be released from red blood cells.
Chloride ions are a component of blood plasma. In the plasma of deoxygenated blood, the chloride ion concentration is between $2$-$3\,\text{mmol dm}^{-3}$ lower than in the plasma of oxygenated blood. Explain why the chloride ion concentration in the plasma of deoxygenated blood is lower than in the plasma of oxygenated blood.