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IB Biology HL C4.2.20 Keeling Curve Analysis Questions

Interpret Mauna Loa atmospheric CO₂ graphs by separating the long-term combustion rise from annual Northern Hemisphere photosynthesis and respiration cycles in IB Biology HL…

Syllabus
First assessment 2025
Course
Biology HL
Level
HL

Exam points

  • Analyse Keeling-curve graphs to distinguish the long-term combustion-driven CO₂ rise from the annual photosynthesis-driven oscillation.
  • Interpret atmospheric CO₂ data by linking seasonal changes to Northern Hemisphere photosynthesis and respiration, and long-term change to fossil-fuel combustion.

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Study C4.2.20—Keeling Curve analysis conceptsOpen the corresponding Concept lesson for explanations, examples and exam connections.

IB Biology HL C4.2.20 Keeling Curve Analysis Questions question 1

[Maximum number: 1]

The graph shows data collected at Mauna Loa, USA, for monthly mean carbon dioxide concentration.

Figure for Question IB Biology HL C4.2.20 Keeling Curve Analysis Questions question 1 — IB Biology HL

What causes the decreases in monthly mean carbon dioxide concentration each year?

A

Combustion increases.

B

Respiration increases.

C

Decomposition increases.

D

Photosynthesis increases.

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