AP BIOLOGY

Detailed explanation-1: -Corn, sorghum, and sugarcane belong to a special group of plants known as C4, so-called because they first fix CO2 into a four-carbon carbohydrate during photosynthesis. On average, C4 crops are 60 percent more productive than C3 crops.

Detailed explanation-2: -Examples of C4 plants include corn, sorghum, sugarcane, millet, and switchgrass. However, the C4 anatomical and biochemical adaptations require additional plant energy and resources than C3 photosynthesis, and so in cooler environments, C3 plants are typically more photosynthetically efficient and productive.

Detailed explanation-3: -C4 plants-including maize, sugarcane, and sorghum-avoid photorespiration by using another enzyme called PEP during the first step of carbon fixation.

Detailed explanation-4: -Corn is a photosynthetic autotroph that uses the C4 photosynthetic pathway. Like most C4 plants, it has a particularly high rate of photosynthesis, has a high water use efficiency (carbon dioxide fixed compared to water loss) and will benefit less from rising carbon dioxide levels than C3 plants (Chapter 20).