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IB Biology SL C1.3.3 Oxygen As By Product Questions

Practise IB Biology SL 8.3.3 by explaining how light splits water and releases oxygen during photosynthesis.

Syllabus
First assessment 2025
Course
Biology SL
Level
SL

Exam points

  • Identify water, rather than carbon dioxide, as the source of oxygen released during photosynthesis.
  • Explain that light-driven photolysis splits water and releases oxygen as a by-product, with hydrogen/electrons supporting photosynthetic reactions.

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Study C1.3.3—Oxygen as by-product conceptsOpen the corresponding Concept lesson for explanations, examples and exam connections.

IB Biology SL C1.3.3 Oxygen As By Product Questions question 1

[Maximum number: 1]

A photosynthesis experiment was carried out using an aquatic plant. The image shows the contents of the test tube after being exposed to light and room temperature for 30 minutes.

Figure for Question IB Biology SL C1.3.3 Oxygen As By Product Questions question 1 — IB Biology SL

What explains the presence of bubbles?

A

Oxygen is formed when carbon dioxide combines with chlorophyll.

B

Carbon dioxide is formed during the light-dependent reaction.

C

Oxygen is released when light splits water molecules in chloroplasts.

D

Carbon dioxide is released from dissociation of sodium hydrogen carbonate.

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