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

Transport of oxygen and carbon dioxide — practice question

Carbon dioxide travels in the blood in several different forms.
(a)[2]

Describe the path taken by carbon dioxide molecules from respiring cells to red blood cells.

(b)[3]

State three differences between the blood at Y and the blood at X apart from carbon dioxide concentration.

(c(i))[1]

Identify the enzyme that catalyses this reaction: $\text{CO}_2 + \text{H}_2\text{O} \rightarrow \text{H}_2\text{CO}_3 \rightarrow \text{H}^+ + \text{HCO}_3^-.$

(c(ii))[3]

Explain why this reaction is important in the transport of carbon dioxide.

(d(i))[1]

State the percentage saturation of haemoglobin with oxygen at an oxygen partial pressure of $5\,\text{kPa}$ when the carbon dioxide partial pressure is: $1.0\,\text{kPa}$ $1.5\,\text{kPa}$.

(d(ii))[2]

The percentage saturation of haemoglobin with oxygen falls as the partial pressure of carbon dioxide rises. Explain why.

(d(iii))[1]

Name the effect of a higher carbon dioxide concentration on the oxygen dissociation curve.

(d(iv))[3]

Explain why the effect of carbon dioxide on haemoglobin shown in Fig. 2.2 is important.

(c)[1]

Name the effect of a higher carbon dioxide concentration on the oxygen dissociation curve.

(d)[3]

Explain why the effect of carbon dioxide on haemoglobin shown in Fig. 2.2 is important.

Worked solution & mark scheme

This 20-mark question has a full step-by-step worked solution and mark scheme. One marking point: Diffusion from a higher to a lower concentration or partial pressure

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