IB Biology SL C1.3.8 Co Enrichment Experiments Questions

Interpret carbon dioxide enrichment data to assess changes in CO₂ uptake and whether elevated atmospheric CO₂ increases maize growth in IB Biology SL C1.3.8.

Exam points

Interpret data showing how increased carbon dioxide concentration affects CO₂ uptake or photosynthesis.
Use crop-growth data to assess whether rising atmospheric CO₂ increases growth, distinguishing its effect from temperature.

[Maximum number: 2]

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 $\mathrm{CO}_{2}$ . Maize plants were grown in natural sunlight in controlled environmental chambers at different temperatures using current atmospheric and doubled $\mathrm{CO}_{2}$ levels.

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

Figure for Question IB Biology SL C1.3.8 Co Enrichment Experiments Questions question 1 — IB Biology SL

Using the data in the graph, discuss whether rising carbon dioxide levels in the atmosphere will increase growth rates in maize.

data does not support idea that rising $\mathrm{CO}_{2}$ levels will increase growth rates in maize
(at all temperatures) there appears to be no difference between exchange rate at current or elevated $\mathrm{CO}_{2}$ levels
temperature has larger effect on growth of maize
so if rising $\mathrm{CO}_{2}$ levels causes more of a greenhouse effect/larger temperature increase, this will affect growth of maize

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IB Biology SL C1.3.8 Co Enrichment Experiments Questions question 1