CAIE A-Level Biology 12 Energy and Respiration Question Bank

Practise ATP, respiratory substrates and aerobic or anaerobic pathways while calculating RQ, analysing respirometers and tracking carbon and reduced coenzymes.

[Maximum number: 4]

There are many mitochondria located in the presynaptic knobs of neuromuscular junctions and in the sarcomeres of muscle fibres of striated muscle.

Explain the need for many mitochondria in the presynaptic knobs and in the sarcomeres.

any four from:

1 mitochondria produce ATP ;

presynaptic knob

2 for production of, acetylcholine / ACh ;

3 for, making / moving, vesicles ; A exocytosis

sarcomere

4 active transport of $\mathrm{Ca}^{2+}$ into, sarcoplasmic reticulum ;

5 detachment of myosin heads / break cross bridge

or

allows myosin head to move back to original position ;

6 AVP ; e.g. ref. to sodium potassium pump / active transport of $\mathrm{Ca}^{2+}$ out of synaptic knob

[Maximum number: 9]

In aerobic respiration，most ATP is produced by oxidative phosphorylation．

(a)

（a）Outline the features of ATP that make it suitable as the universal energy currency．

[ 3 ]

(b)

（b）Rotenone is a compound that affects oxidative phosphorylation．
Rotenone disrupts the first carrier in the electron transport chain by stopping the transfer of electrons from this carrier．

Suggest and explain how rotenone reduces the production of ATP and water in aerobic respiration．

Table for Question (b) — CAIE A-Level Biology A2

[ 6 ]

any six from:

1 ETC / electron flow, less / stops;

2 no / less, energy, available / released / supplied (from electron flow);

3 no / fewer, $\mathrm{H}^{+}$ ions / protons, pumped to intermembrane space;

4 no / smaller, $\mathrm{H}^{+} /$ proton, gradient;

5 no / fewer, protons diffuse through ATP synthase;

6 no / fewer, electrons reach, last carrier / end of chain;

7 no / fewer, electrons can react with oxygen to form water;

8 (oxidised) NAD not regenerated / lack of NAD;

9 no / less, glycolysis / link reaction / Krebs cycle;

10 AVP;

[Maximum number: 2]

The respiratory quotient, RQ, is used to show which substrate is being metabolised by cells. It can be determined using the equation below.

\mathrm{RQ}=\frac{\text { molecules of carbon dioxide released }}{\text { molecules of oxygen taken in }}

Lauric acid is a saturated fatty acid found in coconuts and has a chain of 12 carbon atoms.

Calculate the RQ value for lauric acid.

Show your working. Give your answer to 2 decimal places.
answer =

$RQ=12\div17=0.71$

Accept error carried forward from (i) for one mark.

All question bank results loaded

Covered syllabus points

12. Energy and Respiration question 1

12. Energy and Respiration question 2

Question (a)

Question (b)

12. Energy and Respiration question 3