AP BIOLOGY

Detailed explanation-1: -C3 plants have the disadvantage that in hot dry conditions their photosynthetic efficiency suffers because of a process called photorespiration. When the CO2 concentration in the chloroplasts drops below about 50 ppm, the catalyst rubisco that helps to fix carbon begins to fix oxygen instead.

Detailed explanation-2: -As a plant’s environment becomes hot, dry, and bright, its stomata, where carbon dioxide enters the leaf, tend to close. This lowers the concentration of carbon dioxide into the Calvin cycle, causing the cycle to accept oxygen in place of the carbon dioxide and makes a new product.

Detailed explanation-3: -Photorespiration is the process of taking in molecular oxygen (O2) and releasing carbon dioxide (CO2) from organic substances in response to light. Photorespiration is harmful to C3 plants because it reduces plant productivity, which is why it is also known as a wasteful process.

Detailed explanation-4: -Why does photorespiration happen? If it is too hot or dry, plants often close their stomata to prevent water loss. This prevents CO2 from entering the leaf, as well as prevents O2 from exiting. Oxygen builds up inside the leaf and photorespiration happens instead of the Calvin cycle.