# Answer key

1. **B**: Mitochondria run cellular respiration, which makes ATP.
2. **C**: Every cell needs to make proteins, so every cell has ribosomes.
3. **False**: Plants, fungi, and bacteria have cell walls; animal cells have only a membrane.
4. **oxygen** (also accepted: O2): Photosynthesis splits water and releases O2.
5. **C**: Plants make sugar by photosynthesis and burn it by respiration, like animals do.
6. **C**: Going against the gradient takes energy (ATP), which is active transport.
7. **water** (also accepted: H2O): Osmosis is water moving across a membrane.