A-LevelBiologyPhotosynthesis9700/42 · Oct/Nov 2018 · Q79 Marks

[Figure 7.1] is an outline diagram of the Calvin cycle.

(a)(i)With reference to Fig. 7.1: name the stage of the Calvin cycle occurring at A name the enzyme involved in the stage of the Calvin cycle occurring at A name two examples of substance C 1 2 name the biochemical process that produces reduced NADP and ATP.[5]
(a)(ii)With reference to Fig. 7.1, outline what is occurring at stage B of the Calvin cycle.[1]
(b)Explain why there is a tight ring of mesophyll cells around the bundle sheath cells in the leaves of a C4 plant.[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 (Oct/Nov 2018). The mark or mark type is shown in brackets.

[5] 1 carbon (dioxide) fixation / carboxylation ; 2 rubisco/ribulose bisphosphate carboxylase oxygenase ; 3 two named substances ;; e.g. starch, cellulose, fatty acids, lipids, sucrose 4 5 photophosphorylation ; A light-dependent stage
[1] regeneration of RuBP;
[3] any three from: 1 stops oxygen getting to, rubisco / RuBP / bundle sheath cells ; 2 oxygen does not, react with rubisco / combine with RuBP ; 3 no photorespiration; 4 no wastage of RuBP ;

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.