Correct Response: A. Land plants take in carbon dioxide from the atmosphere through pores in their leaves called stomata. Such pores are necessary because the leaves of land plants are coated in a waxy covering called the cuticle. The cuticle prevents water loss but also limits gasses from diffusing directly into the leaves. Aquatic autotrophs such as algae lack a cuticle. This allows aquatic autotrophs to obtain dissolved carbon dioxide from the water primarily by diffusion, so stomata are not needed. Aquatic plants and land plants both contain chlorophyll a (B), produce NADPH during the light reactions (C), and use a chemiosmotic mechanism for producing ATP (D).
