AP BIOLOGY

Detailed explanation-1: -In C4 plants the carbon dioxide is initially fixed into four carbon atom containing organic acids, like malate and oxalo acetic acid. The carbon dioxide is fixed initially in the chloroplasts of spongy mesophyll tissue by the enzyme PEP carboxylase.

Detailed explanation-2: -C4 plants-including maize, sugarcane, and sorghum-avoid photorespiration by using another enzyme called PEP during the first step of carbon fixation. This step takes place in the mesophyll cells that are located close to the stomata where carbon dioxide and oxygen enter the plant.

Detailed explanation-3: -In the C4 pathway, initial carbon fixation takes place in mesophyll cells and the Calvin cycle takes place in bundle-sheath cells. PEP carboxylase attaches an incoming carbon dioxide molecul to the three-carbon molecule PEP, producing oxaloacetate (a four-carbon molecule).

Detailed explanation-4: -In C4 plants for synthesis of hexose sugars, final CO2 fixation occurs in Epidermis cell Spongy cells Undifferentiated mesophyll cells Bundle sheath cells.

Detailed explanation-5: -C4 plants have two types of photosynthetic cells: mesophyll (M) cells and bundle sheath (BS) cells, which have numerous well-developed chloroplasts.