Biology 9700 · AS & A Level · Protein synthesis

Protein synthesis — practice question

The induced-fit hypothesis and the lock-and-key hypothesis describe the mode of action of enzymes.
(a)[3]

Explain how the induced-fit hypothesis accounts for enzyme action.

(b)

Radish plants contain the enzyme peroxidase, which catalyses the breakdown of hydrogen peroxide. Students studied how increasing the concentration of hydrogen peroxide affected the activity of peroxidase extracted from radish. Their results are shown in Fig. 4.1.

(b(i))[3]

Explain the effect of increasing the hydrogen peroxide concentration on the initial rate of reaction shown in Fig. 4.1.

(b(ii))[2]

The students found the $K_m$ for radish peroxidase to be $0.10\,\text{mmol dm}^{-3}$. Using Fig. 4.1, describe how they worked out the $K_m$.

(c)[3]

A further investigation found that the $K_m$ for carbonic anhydrase is $12\,\text{mmol dm}^{-3}$. Describe the role of carbonic anhydrase in the transport of carbon dioxide.

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