9. Photosynthesis

Why are C₄ plants more suited to hot climates than C₃ plants?

The use of non-C₃ and non-CAM plants as crops may be limited in some regions because on hot, dry days, they close their stomata. What happens as a result of closing their stomata?

How is photosynthesis similar in C4 plants and CAM plants? a. In both cases, only photosystem I is used. b. Both types of plants make sugar without the Calvin cycle. c. In both cases, rubisco is not used to fix carbon initially. d. Both types of plants make most of their sugar in the dark.

What is the role of PEP carboxylase in C4 and CAM plants? a. It fixes CO2 into an organic acid. b. It produces ATP for the Calvin cycle. c. It replaces rubicso in the Calvin cycle. d. It releases CO2 from organic acids.

Why is it difficult for C3 plants to carry out photosynthesis in very hot, dry environments such as deserts? a. The light is too intense and destroys the pigment molecules. b. The closing of stomata keeps CO2 from entering and O2 from leaving the plant. c. They must rely on photorespiration to make ATP. d. CO2 builds up in the leaves, blocking carbon fixation.

How is photosynthesis similar in C4 plants and CAM plants? a. In both cases, the light reactions and the Calvin cycle are separated in both time and location. b. Both types of plants make sugar without the Calvin cycle. c. In both cases, rubisco is not used to fix carbon initially. d. Both types of plants make most of their sugar in the dark.