Final answer:
Primary producers in land ecosystems, including plants and other photoautotrophs, use sunlight to produce food through photosynthesis, converting solar energy into chemical energy.
Step-by-step explanation:
According to the figure on the previous page, the primary producers in land ecosystems use solar energy to make food. Photoautotrophs, such as plants, algae, and photosynthetic bacteria, are key to this process as they capture the sun's energy and convert it into chemical energy through photosynthesis. This energy is stored in molecules like ATP (and NADP) and is used to synthesize glucose. These organic compounds then provide the necessary energy for the rest of the ecosystem as they are consumed by primary consumers and passed through the food web.