Given a scientific question, generate a correct answer to it.

Input: Consider Input: What living things are considered photoautotrophs because they use sunlight and carbon from carbon dioxide to synthesize chemical energy in the form of carbohydrates?

Output: plants

Input: Consider Input: In living systems, diffusion of substances into and out of cells is mediated by the what membrane?

Output: plasma

Input: Consider Input: Where are all hormones secreted into before entering the circulatory system?
Output: interstitial fluid