Rubisco Is an Important Enzyme in the Calvin Cycle

question 50

Essay

Rubisco is an important enzyme in the Calvin cycle.It catalyzes the addition of carbon dioxide and water to ribulose-1,5-bisphosphate,which then forms two molecules of 3-phosphoglycerate.Rubisco acts as a carboxylase and is essential for carbon fixation.
a. Rubisco has an additional function.It can also function as an oxygenase.Why is this a problem for plants?
b. Rubisco has a much lower affinity for oxygen than for carbon dioxide.Why is the oxygenase activity still a problem for plants?
c. What is (are)the product(s)of the reaction when rubisco acts as an oxygenase?
d. How does the plant deal with the product of the oxygenase reaction?
e. The oxygenase activity of rubisco is particularly a problem for plants in arid environments.Can you explain why?
f. What strategies do plants in arid environments use to deal with this problem?

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