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IB Biology SL C1.3.7 Limiting Factors Investigation Questions

Vary light intensity, carbon dioxide concentration or temperature to investigate limiting factors, then measure photosynthesis rate using oxygen production or carbon dioxide uptake.

Syllabus
First assessment 2025
Course
Biology SL
Level
SL

Exam points

  • Interpret photosynthesis data or graphs to identify whether light intensity, carbon dioxide concentration or temperature is limiting the rate.
  • Describe controlled investigations that vary one factor and estimate photosynthesis rate from oxygen production or carbon dioxide uptake.

IB Biology SL C1.3.7 Limiting Factors Investigation Questions question 1

[Maximum number: 1]

Global atmospheric carbon dioxide levels are rising. A study was carried out to test if the temperature dependence of photosynthesis was altered by elevated atmospheric CO2\mathrm{CO}_{2}. Maize plants were grown in natural sunlight in controlled environmental chambers at different temperatures using current atmospheric and doubled CO2\mathrm{CO}_{2} levels.

The graph below shows daily patterns of CO2\mathrm{CO}_{2} exchange at three different temperatures. Open shapes ( o,Δ,v\mathrm{o}, \Delta, \mathrm{v} ) represent current atmospheric CO2\mathrm{CO}_{2} levels and closed shapes ( ∙,Δ,m\bullet, \mathbf{\Delta}, \mathbf{m} ) represent elevated CO2\mathrm{CO}_{2} levels.

Figure for Question IB Biology SL C1.3.7 Limiting Factors Investigation Questions question 1 — IB Biology SL

State the temperature that resulted in the highest rate of photosynthesis under current atmospheric conditions.

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