Which statement best describes C3 plants?

Which statement best describes C3 plants?

• A. Decrease photorespiration and minimize energy loss.
• B. Are adapted to very dry environments by closing stomata during the day.
• C. Make up more than 85% of plants, have no special adaptations to stop photorespiration from occurring.
• D. Fix CO2 into a four-carbon compound to concentrate CO2.

Answer: (C)

C3 plants fix CO2 directly through the Calvin cycle using Rubisco, without any mechanism to concentrate CO2 around the enzyme. This pathway is by far the most common among plants, making up the majority of species. Because there isn’t a CO2-concentrating system, Rubisco can also fix O2, especially when CO2 levels fall during hot, sunny, and dry conditions when stomata close to conserve water. This leads to photorespiration, which reduces efficiency. That's why C3 plants don’t have special adaptations to stop photorespiration. The idea of closing stomata in very dry environments points to drought-avoidant strategies seen in CAM or C4 plants, not a defining feature of C3. And fixing CO2 into four-carbon compounds describes the C4 pathway, which uses a carbon-concentrating mechanism. So the statement that best fits describes C3 plants as the vast majority of species with no special adaptation to prevent photorespiration.

C3 plants fix CO2 directly through the Calvin cycle using Rubisco, without any mechanism to concentrate CO2 around the enzyme. This pathway is by far the most common among plants, making up the majority of species. Because there isn’t a CO2-concentrating system, Rubisco can also fix O2, especially when CO2 levels fall during hot, sunny, and dry conditions when stomata close to conserve water. This leads to photorespiration, which reduces efficiency. That's why C3 plants don’t have special adaptations to stop photorespiration. The idea of closing stomata in very dry environments points to drought-avoidant strategies seen in CAM or C4 plants, not a defining feature of C3. And fixing CO2 into four-carbon compounds describes the C4 pathway, which uses a carbon-concentrating mechanism. So the statement that best fits describes C3 plants as the vast majority of species with no special adaptation to prevent photorespiration.