Biology 9700 · AS & A Level · Respiration

Respiration — practice question

When water is taken up by a dormant seed, germination begins and the respiration rate rises.
(a)[1]

Name the plant growth regulator responsible for starting seed germination.

(b(i))[1]

State the function of potassium hydroxide solution when a respirometer is used.

(b(ii))[3]

As respiration occurs, oxygen is consumed by the seeds and the coloured liquid drops down the tube. Describe the role of oxygen in aerobic respiration.

(c(i))[1]

Suggest why the respirometers were left for $10$ minutes before any readings were taken.

(c(ii))[2]

Suggest why respirometers B and D were included in this investigation.

(c(iii))[2]

Calculate the oxygen uptake rate in $\text{cm}^3$ per minute for respirometer C from 5 to 20 minutes. Your answer should be to two significant figures. Show your working.

(c(iv))[2]

Explain why germinating pea seeds respire faster between $10\,^{\circ}\text{C}$ and $25\,^{\circ}\text{C}$.

(c(v))[2]

Suggest why carrying out the experiment with germinating seeds at $50\,^{\circ}\text{C}$ might give a lower respiration rate than at $25\,^{\circ}\text{C}$.

Worked solution & mark scheme

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