A-LevelBiologyControl and coordination9700/43 · May/June 2025 · Q913 Marks

Most carnivorous mammals need to move to hunt their prey.

(a)Outline why a carnivorous mammal makes more use of its nervous system, rather than its endocrine system, when it hunts.[4]
(b)Fig. 9.1 is a diagram of a motor neurone. [Figure 9.1] On Fig. 9.1, add label lines and the letters R, S and T to label a part of the neurone that: • can become depolarised – use the letter R • contains many mitochondria – use the letter S • acts as an insulator – use the letter T.[3]
(c)(i)Fig. 9.2 summarises changes that occur during the contraction of a sarcomere. [Figure 9.2] Suggest an explanation for the shape of the curve that shows changes in the width of the sarcomere.[3]
(c)(ii)Suggest an explanation for the curve that shows changes in calcium ion concentration.[3]

This question uses a diagram from the original paper, which isn't shown here. Open the full paper from the past papers archive to see it.

Mark scheme

Marking points from the official mark scheme (May/June 2025). The mark or mark type is shown in brackets.

[4] 9(a) any four from: 1 use (named) sense organs to detect prey ; 2 faster transmission of, impulses / signals; 3 (so) faster reaction to stimuli ; 4 ref. to control centre / brain / CNS (decision making) ; 5 faster response or ref. reflexes; 6 (by) muscles;
[3] 9(b) (if a letter is used more than once, all must be correct) correct position of label and letter for: R; S; T; [Image shows a neuron with parts labeled: S on the cell body, T on the myelin sheath/Schwann cell, R on the axon/axon terminal.]
[3] 9(c)(i) any three from: increase in curve 1 cross bridges form / myosin heads bind to actin; 2 power stroke / actin filaments slide over myosin filaments ; 3 bands get, smaller/shorter or decrease in width of sarcomere ; decrease in curve 4 breaking of cross bridges / detachment of myosin heads from actin ; 5 bands get, bigger/longer or increases width of sarcomere ;
[3] 9(c)(ii) increase 1 calcium ions / Ca2+, released by sarcoplasmic reticulum ; 2 calcium ions / Ca2+, bound to troponin ; decrease 3 calcium ions / Ca2+, pumped back into sarcoplasmic reticulum ;

On Oracle Prep you can write or photograph your own answer and have it marked by AI against this mark scheme, with feedback on what you missed.