Biology 9700 · AS & A Level · Transport of oxygen and carbon dioxide

Transport of oxygen and carbon dioxide — practice question

Researchers measured the concentrations of sodium ions and potassium ions in red blood cells and in blood plasma from a group of people. Table 1.1 presents the results, with mean concentrations expressed in $\text{mmol dm}^{-3}$.
(a(i))[3]

Use the information in Table 1.1 to identify and describe the mechanism by which potassium ions enter red blood cells from the blood plasma.

(a(ii))[2]

Sodium ions and oxygen molecules both enter red blood cells. State one similarity and one difference between the mechanisms used by sodium ions and oxygen molecules to enter red blood cells.

(a(iii))[2]

Chloride ions pass across the membrane of human red blood cells in a process known as the chloride shift. Explain why the chloride shift is important for the transport of carbon dioxide from respiring tissues.

(b)[1]

Scientists investigated the uptake of a substance, $F$, by human red blood cells. The red blood cells were placed in a solution containing substance $F$ for $30$ minutes. After this period, the scientists observed that the cell surface membrane of the red blood cells had infoldings (invaginations) and that the number of vesicles in the cytoplasm had increased. Identify the process by which substance $F$ entered the red blood cells.

Worked solution & mark scheme

This 8-mark question has a full step-by-step worked solution and mark scheme. One marking point: Active uptake / active transport

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