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CAIE A-Level Biology A2 13.1 Photosynthesis As Energy Transfer Process Questions

Practise how chloroplast structure, pigments and light-dependent reactions supply ATP and reduced NADP for carbon fixation and product formation in the Calvin cycle.

Syllabus
2028–2030
Course
Biology 9700
Level
A2

Exam points

  • Relate stacked grana and thylakoid membranes to light reactions, and stroma to the Calvin cycle.
  • Explain how chlorophyll a, chlorophyll b, carotene and xanthophyll widen light absorption.
  • Interpret absorption spectra of pigments and the action spectrum for photosynthesis.
  • Use chromatography and Rf values to separate and identify chloroplast pigments.
  • Compare cyclic and non-cyclic photophosphorylation by photosystems, electron paths and products.
  • Describe water photolysis releasing oxygen and electron flow producing reduced NADP.
  • Interpret pH evidence and trace proton pumping and ATP synthase return in chemiosmosis.
  • Trace rubisco-catalysed fixation of CO2 with RuBP through an unstable six-carbon compound to GP.
  • Trace GP reduction to TP using ATP and reduced NADP, then RuBP regeneration using ATP.
  • Connect GP to some amino acids and TP to carbohydrates, lipids and amino acids.

Covered syllabus points

13.1.1—Chloroplast structure-function relationship13.1.2—ATP and reduced NADP in Calvin cycle13.1.3—Sites within chloroplast13.1.4—Chloroplast pigments in light absorption13.1.5—Absorption and action spectra13.1.6—Pigment chromatography13.1.7—Light-dependent stage13.1.8—Cyclic photophosphorylation13.1.9—Non-cyclic photophosphorylation13.1.10—During photophosphorylation13.1.11—Calvin cycle three main stages13.1.12—Calvin cycle intermediates

Question 1

[Maximum number: 7]

Chloroplasts carry out photosynthesis.
Fig. 1.1 shows some structural features of a chloroplast and some processes that occur within it.

Fig. 1.1

Fig. 1.1

Question (a)

(a)

Identify the structures labelled A in Fig. 1.1.

[ 1 ]

Question (b)

(b)

Explain how the structure and appearance of the granum, and the components labelled A, relate to their function.

[ 4 ]

Question (c)

(c)

Explain why pathway C is described as a cycle.

[ 2 ]

Question 2

[Maximum number: 7]

Photosynthesis is the energy transfer process that occurs in chloroplasts.
Fig. 5.1 shows some biochemical events that occur in a chloroplast during the light-dependent stage of photosynthesis. Photosystems I and II (PSI and PSII) and some associated proteins of the thylakoid membrane are shown.

Fig. 5.1

Fig. 5.1

Question (a)

(a)

A and B are areas of the chloroplast. Name areas A and B.

A

B

[ 2 ]

Question (b)

(b)

The group of proteins labelled C, PSI and the protein labelled E are involved in a specific biochemical process during the light-dependent stage of photosynthesis.

Name this specific biochemical process and the protein labelled E.
process
E

[ 2 ]

Question (c)

(c)

Product D is used during the Calvin cycle.

Identify product D and describe its specific role in the Calvin cycle.

[ 3 ]
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