Biology 9700 · AS & A Level · Respiration

Respiration — practice question

Different respiratory substrates can possess different energy values, so they release different amounts of energy when respired.
(a)[1]

Complete Table 1.1 to indicate the energy value of each of the three main types of respiratory substrate. Use one tick ($(\checkmark)$) to show which of the two possible energy values is correct for each respiratory substrate.

(b(i))[1]

State the name of the laboratory apparatus that may be used to determine the RQ value of organisms such as blowfly larvae.

(b(ii))[1]

When RQ values are being determined with the laboratory apparatus named in (b)(i), chemicals such as soda lime or potassium hydroxide solution are used. State why chemicals such as soda lime or potassium hydroxide solution are used when measuring RQ values.

(c(i))[1]

Calculate how many molecules of oxygen are taken in when one molecule of malic acid is respired aerobically.

(c(ii))[1]

Calculate the RQ for malic acid. Give your answer correct to two decimal places.

(d)

Using Fig. 1.3, answer the questions about how the RQ of the deer mouse changes over the day that included a period in torpor.

(d(i))[3]

Describe the pattern during torpor shown in Fig. 1.3 and suggest why it occurs.

(d(ii))[2]

Deer mice have a daily period of torpor only at certain times of the year. Suggest reasons why a deer mouse enters torpor only at certain times of the year.

Worked solution & mark scheme

This 10-mark question has a full step-by-step worked solution and mark scheme. One marking point: All three are correct: carbohydrate has an energy value of about $17\,\text{kJ g}^{-1}$, lipid about $37\,\text{kJ g}^{-1}$, protein about $17\,\text{kJ g}^{-1}$

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