Biology revision, unit 2: cells

Mitochondria are where aerobic respiration happens. They make most of the cell's ATP.
The nucleus holds the DNA. It is not where proteins are made: ribosomes make proteins.
Chloroplasts are found in plant cells only. Animal cells do not have them.

Osmosis is the movement of water across a partially permeable membrane, from a dilute solution to a more concentrated one. Osmosis is not active transport and needs no energy from the cell.
Active transport moves substances against a concentration gradient and does need energy.

Enzymes are not used up in a reaction. Each enzyme works best at its optimum temperature; human enzymes work best at about 37 degrees Celsius.

Photosynthesis: carbon dioxide + water -> glucose + oxygen. It needs light.