Pearson Edexcel IAL Biology 5.4 Light-independent reactions & Calvin cycle products

Practise Calvin cycle steps, GP, GALP, RuBP and RUBISCO roles, and how photosynthetic products become glucose, sucrose and biomass.

Exam points

use Calvin cycle diagrams to link CO2 fixation, GP formation, GALP and RuBP regeneration
calculate ATP to reduced NADP ratios from labelled cycle data for glucose production
explain how GALP is converted into sugars and biomass in plant tissues

[Maximum number: 5]

Photosynthesis consists of the light-dependent reactions and the light-independent reactions.

(a)

The light-independent reactions use products of the light-dependent reactions to produce simple sugars.

[ 5 ]

(i)

Simple sugars have the formula $\mathrm{C}_{n} \mathrm{H}_{2 n} \mathrm{O}_{n}$ .

Name the inorganic molecule from which each element in a simple sugar originated.

C

H

O

[ 2 ]

An answer that includes the following points:

- C and O from carbon dioxide (1)

- H from water (1)

ACCEPT CO2

ACCEPT $\mathrm{H}_{2} \mathrm{O}$

DO NOT ACCEPT O from water

(2)

(ii)

Simple sugars are used in the synthesis of new biological molecules.

Which row of the table shows the inorganic ions that are needed to synthesise these new biological molecules?

Table for Question (ii) — Edexcel A-Level Biology A2

[ 3 ]

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5.4—Light-independent reactions and Calvin cycle products question 1

Question (a)

Question (i)

Question (ii)