A-LevelBiologyControl and coordination9700/41 · Oct/Nov 2025 · Q513 Marks

The endocrine system and the nervous system both coordinate responses in mammals. (a) Complete Table 5.1 to show the features of three cell-signalling molecules of the endocrine system: antidiuretic hormone (ADH), glucagon and insulin. Use a tick (✔) if the molecule has the feature and a cross (X) if the molecule does not have the feature. Put a tick (✔) or a cross (X) in every box. Table 5.1 feature ADH glucagon insulin binds to receptors on cell surface membranes results in molecules moving from cells into the blood is secreted as a result of detection by osmoreceptors

(a)Complete Table 5.1 to show the features of three cell-signalling molecules of the endocrine system: antidiuretic hormone (ADH), glucagon and insulin. Use a tick (✔) if the molecule has the feature and a cross (X) if the molecule does not have the feature. Put a tick (✔) or a cross (X) in every box. Table 5.1 feature ADH glucagon insulin binds to receptors on cell surface membranes results in molecules moving from cells into the blood is secreted as a result of detection by osmoreceptors[3]
(b)The endocrine system has a slower transmission speed than the nervous system. Describe other ways in which the endocrine system and the nervous system differ.[4]
(c)(i)State the letter on Fig. 5.1 that indicates the length of a sarcomere.[1]
(c)(ii)State the letter on Fig. 5.1 that indicates a region where actin and myosin overlap.[1]
(c)(iii)Describe and explain how the region labelled D on Fig. 5.1 changes during muscle contraction.[4]

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Mark scheme

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

[1] (a) binds to receptors on cell surface membranes: ADH (✔), glucagon (✔), insulin (✔) ;
[1] results in molecules moving from cells into the blood: ADH (✔), glucagon (✔), insulin (X) ;
[1] is secreted as a result of detection by osmoreceptors: ADH (✔), glucagon (X), insulin (X) ;
[4] (b) any four from: 1 impulses / action potentials / neurotransmitters, in nervous system and hormones in endocrine system ; 2 electrical in nervous system and chemical in endocrine system ; 3 neurones / nerve cells, in nervous system and blood in endocrine system ; 4 effects are / target is, specific / localised, in nervous system and (can be) widespread in endocrine system ; 5 effect / response, happens quickly in nervous system and slowly in endocrine system ; 6 effect / response, lasts a short time in nervous system and long time in endocrine system ; 7 AVP ;
[1] (c)(i) C ;
[1] (c)(ii) B ;
[1] (c)(iii) 1 (D / it), shortens / contracts / decreases ;
[3] and any three from: 2 calcium ions / Ca2+, bind to troponin ; 3 tropomyosin, moves / shifts position / exposes binding sites on actin ; 4 myosin (head) binds to actin / myosin-actin cross-bridges form ; 5 power stroke / myosin head, pulls actin ; 6 more actin, enters / overlaps with, A band / B or more overlap between actin and myosin ;

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