Pearson Edexcel IAL Biology 5.2 Photophosphorylation, ATP & energy supply

Practise ATP and photophosphorylation by distinguishing ADP phosphorylation from ATP hydrolysis and linking ATP to energy supply.

Exam points

distinguish ADP phosphorylation requiring energy from ATP hydrolysis releasing energy
complete ATP equations with ADP, inorganic phosphate and the correct reaction type
explain why light energy is converted into ATP for use in biological processes

[Maximum number: 4]

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

(a)

In the light-dependent reactions, light energy is converted into energy stored in ATP.

[ 4 ]

(i)

Explain why light energy is converted into energy stored in ATP.

[ 2 ]

(ii)

An equation can summarise the production and breakdown of ATP.

Complete this equation, by writing the names of the substrates and the type of reaction on the three dotted lines provided. +

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

phosphorylation

[ 2 ]

An answer that includes the following points:

- (ADP / adenosine diphosphate) and (inorganic) \{Pi / phosphate / $\mathrm{PO}_{4}{ }^{3-}$ (ion)\} (1)

- hydrolysis (1)

ACCEPT adp DO NOT ACCEPT P / phosphorus

ACCEPT dephosphorylation

(2)

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5.2—Photophosphorylation, ATP and energy supply question 1

Question (a)

Question (i)

Question (ii)