Edexcel A-Level Biology A2 5.2 Photophosphorylation Atp and Energy Supply Questions

Distinguish phosphorylation from hydrolysis, identify ATP as an energy-transfer molecule and connect light energy to ATP production in photosynthesis.

Exam points

describe ATP hydrolysis as an energy-releasing reaction for biological processes
explain why light energy is converted into energy stored in ATP
distinguish phosphorylation of ADP from ATP hydrolysis and identify their substrates/products

[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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Edexcel A-Level Biology A2 5.2 Photophosphorylation Atp and Energy Supply Questions question 1

Question (a)

Question (i)

Question (ii)