How do autotrophs capture the energy in sunlight?
They use photosynthesis. The sunlight hits the photosystems in the chloroplasts, bouncing off electrons. They pass through an electron transport chain that creates ATP. Sunlight also breaks water down into hydrogen, oxygen, and electrons. The oxygen goes out as a byproduct (very important for our survival), the electrons return to the photosystems to replace what was lost when sunlight bounced them off, and the hydrogen goes to NADP+ to make NADPH. NADPH and ATP go off into the dark reactions, also known as the Calvin cycle. This occurs in the stroma, which is the juice of the chloroplast. Here, the NADPH drops off the hydrogen and returns to the light reactions as NADP+ for more hydrogen. Carbon dioxide enters through the plant’s stomata (openings in the leaves that allow for gas exchange) and enter the dark reactions. So now we have all the components of glucose – carbon, hydrogen, and oxygen. The ATP molecules from the light reactions breaks down into ADP and phosphate, releasing en
