Question

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Please answer the following question(s):
1. Photosynthesis among some desert plants is often different from that in moister areas. These desert
plants must control loss of water by shutting their stomata during the daylight hours. But when the
stomata are closed, CO₂ cannot enter the leaf and O₂ cannot leave it, and photosynthesis cannot
continue. Why?
O a. There is no sunlight energy available to drive photosynthesis during the hottest part of the day.
b.
The carbon in CO₂ is necessary to make the sugars in the light independent part of
Photosynthesis.
O c. There is no water available to make the sugars in the light independent part of photosynthesis.
d.
When the stomata are closed the O₂ is quickly used up in photosynthesis and the plants will
become stressed

Answer 1

The correct answer is (b) The carbon in CO₂ is necessary to make the sugars in the light-independent part of photosynthesis. During photosynthesis, carbon dioxide (CO₂) is converted into glucose, which is the energy source for the plant. In the light-independent part of photosynthesis (also called the Calvin cycle), CO₂ is used to produce glucose with the help of energy from ATP and NADPH produced during the light-dependent part of photosynthesis. If the stomata are closed, CO₂ cannot enter the leaf, and therefore the light-independent part of photosynthesis cannot continue. This is why desert plants must balance water conservation with the need for photosynthesis by opening their stomata at night when the air is cooler and more humid, and closing them during the day to prevent water loss.