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CAIE IGCSE Biology 19.3.1 Carbon cycle

Practise tracing carbon through CO2, organisms, decomposers, fossil fuels and combustion in diagrams, tables and explanations.

Syllabus
2026–2028
Course
Biology 0610

Exam points

  • identify carbon-cycle arrows for photosynthesis, respiration, decomposition and combustion
  • explain changes in atmospheric CO2 after deforestation using reduced photosynthesis
  • link decomposer respiration to CO2 release from dead material and waste

19.3.1—Carbon cycle question 1

[Maximum number: 4]

Question (a)

(a)

Fig. 6.1 shows part of the carbon cycle in the ocean.

Fig. 6.1 (not to scale)

Fig. 6.1 (not to scale)

[ 4 ]

Question (i)

(i)

Phytoplankton contain chlorophyll.

Explain how phytoplankton lower carbon dioxide concentrations in the atmosphere.

[ 2 ]

Question (ii)

(ii)

State the names of two processes that add carbon dioxide to the atmosphere.

1
2

[ 2 ]
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