Q1 - Enzyme-Limited Carbon Fixation in a Warming Amazon

Theoretical B Real exam question - full text reproduced under IBO's CC BY-NC-SA 4.0 license

Calvin Cycle, Photorespiration & C4/CAM Biochemistry Ecology

Forests sink more than 30% of anthropogenic CO , but the way they handle atmospheric CO is changing. This 2 2 map shows the change in total fixed carbon mass in the Amazon over the last decade. The Amazon rainforest is responding to climate change similarly to most rainforests.

Figure 1 for Q1: Enzyme-Limited Carbon Fixation in a Warming Amazon

Using the information and data, determine which of the statements are true or which are false.

A. Excluding deforestation, rainforests have shown a net increase in carbon biomass in recent years.

B. Increasing UV input, due to a thinning ozone layer, can increase carbon fixation.

C. Increasing atmospheric CO concentration can increase carbon fixation. 2

D. Small increases in temperature increases the rate of photosynthetic enzymes.

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Question reproduced from IBO 2017, Theoretical Exam B, licensed under CC BY-NC-SA 4.0 - attributed to the International Biology Olympiad. Open the full exam PDF · Official answer key & worked solutions