Final answer:
The correct answer is B. Energy inputs occur via photosynthesis or ingesting food; the energy is released by respiration and cycles back into the ecosystem as heat.
Step-by-step explanation:
Energy inputs in cells occur via photosynthesis or ingesting food; this energy drives the flow of matter into and out of the cell. The energy is released by respiration and eventually cycles back into the ecosystem as heat.
Photosynthesis absorbs light energy to build carbohydrates in chloroplasts while aerobic cellular respiration releases energy by using oxygen to metabolize carbohydrates in the cytoplasm and mitochondria. Both processes use electron transport chains to capture the necessary energy to power other cellular reactions, functioning in a biological cycle to enable organisms to access life sustaining energy. Moreover, ecosystems need a constant influx of energy, with sunlight entering ecosystems mainly through photosynthesis, and then the energy flows throughout the food web from producers to consumers.