AP BIOLOGY

Detailed explanation-1: -In C4 plants the photosynthesis takes place in a thin-walled mesophyll cell and a 4-carbon acid is handed off to a thick-walled bundle sheath cell, where the Calvin cycle occurs in a chloroplast of that second cell.

Detailed explanation-2: -In C4 plants, calvin cycle occurs in bundle sheath cells and not in mesophyll cells.

Detailed explanation-3: -C4 plants have a distinctive leaf anatomy (Kranz anatomy), with chloroplast-rich bundle-sheath cells, which form a gas-tight cylinder surrounding the vascular bundle.

Detailed explanation-4: -In C4 photosynthesis, where a four-carbon compound is produced, unique leaf anatomy allows carbon dioxide to concentrate in ‘bundle sheath’ cells around Rubisco. This structure delivers carbon dioxide straight to Rubisco, effectively removing its contact with oxygen and the need for photorespiration.

Detailed explanation-5: -The C4 pathway acts as a mechanism to build up high concentrations of carbon dioxide in the chloroplasts of the bundle sheath cells. The resulting higher level of internal carbon dioxide in these chloroplasts serves to increase the ratio of carboxylation to oxygenation, thus minimizing photorespiration.