IB Biology HL C1.3 Photosynthesis questions

Exam-style multiple choice and written questions with full markschemes. Check multiple choice answers straight away, or type, photograph or draw a written answer and get it marked.

Type
Multiple choiceWritten
Difficulty
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Question 1

Multiple choiceEasy1 mark

Equal amounts of GP were added to four reaction mixtures. ATP and reduced NADP were added as indicated; all other conditions and the time interval were identical. The amount of TP formed after 1 min was measured.

MixtureATP addedReduced NADP addedTP formed / μmol
1YesNo0.0
2NoYes0.0
3YesYes2.4
4NoNo0.0

Which combination was present in the mixture that formed TP?

Show answer and explanation

Answer: C. Only mixture 3 formed TP, and it contained both ATP and reduced NADP. This matches the conversion of GP into TP, which uses ATP and reduced NADP.

A: assumes ATP alone is sufficient; mixture 1 formed no TP. B: assumes reduced NADP alone is sufficient; mixture 2 formed no TP. D: selects the mixture without either compound, which formed no TP.

Remember: GP conversion to TP requires both ATP and reduced NADP.

Question 2

Paper 2Easy5 marks

During a simplified accounting of the Calvin cycle in a leaf, six molecules of triose phosphate are produced. One molecule leaves as net product; the remainder is used to regenerate RuBP.

(a)

Determine the number and fraction of the triose phosphate molecules used to regenerate RuBP.

[2]
(b)

State the number of RuBP molecules regenerated from these five triose phosphate molecules.

[1]
(c)

Explain the role of ATP in RuBP regeneration and why regenerated RuBP is needed for the Calvin cycle to continue.

[2]

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