A-LevelBiologyControl and coordination9700/41 · May/June 2022 · Q19 Marks

(a) The golden mantella, Mantella aurantiaca, is a small terrestrial frog found in Madagascar. [Figure 1.1]

(a)(i)Name the domain and kingdom to which the golden mantella belongs. domain kingdom[2]
(a)(ii)The skin of the golden mantella is brightly coloured and contains a toxin. Suggest a benefit to the frog of being brightly coloured.[1]
(b)The toxin in the skin of the golden mantella affects the action of the sarcomeres in muscle fibres (muscle cells) of mammalian striated muscle. The toxin inhibits a protein, Ca²⁺ATPase, found in the membrane of the sarcoplasmic reticulum. Ca²⁺ATPase pumps calcium ions from the cytoplasm into the sarcoplasmic reticulum when the fibre is no longer stimulated. Suggest the consequences to the sarcomere of the action of the golden mantella toxin.[3]
(c)Describe the role of calcium ions in a cholinergic synapse.[3]

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Mark scheme

Marking points from the official mark scheme (May/June 2022). The mark or mark type is shown in brackets.

[2] (a)(i) Eukarya; Animalia;
[1] (a)(ii) any one from: warning to predators / to deter predators; AVP;
[3] (b) any three from: 1 Ca2+ (stays) in, cytoplasm / sarcoplasm ; 2 Ca2+, binds / bound, to troponin ; 3 tropomyosin, shifted / does not cover (myosin) binding sites (on actin); 4 myosin-actin, cross bridges / bonds, exist / remain ; 5 sarcomere(s) / muscle, contracted / shortened / paralysed ;
[3] (c) any three from: 1 Ca2+, enters / diffuses into, synaptic knob ; 2 through (voltage-gated) calcium (ion) channels ; 3 vesicles containing acetylcholine ; 4 move to/fuse with, presynaptic membrane ; 5 exocytosis of acetylcholine ;

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