DENDROLOGY

Detailed explanation-1: -CO2 must also diffuse from substomatal cavities throughout the mesophyll, dissolve in wet cell walls, cross the plasma membrane to enter the cytosol, diffuse into chloroplasts across a double membrane (outer envelope in Figure 1.7) and finally reach fixation sites within the stroma of those chloroplasts.

Detailed explanation-2: -Carbon dioxide enters the leaf cells through small holes present on the lower side of the leaf called stomata and then reaches the cell’s chloroplast. CO2 moves across the cell membrane through the process of simple diffusion.

Detailed explanation-3: -Answer and Explanation: The carbon dioxide used in photosynthesis enters the plant by c) diffusion through stomata into the leaves.

Detailed explanation-4: -The diffusion is facilitated by CA (Cowan, 1986) which interconverts CO2 and bicarbonate, because at the pH of the stroma (pH up to 8), the ratio of bicarbonate to CO2 is ∼50. The majority of CA activity in leaves is thought to be localized within chloroplasts.