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The human body takes in oxygen and lets out carbon dioxide. Many parts of the body are involved, including the lungs, airways and blood.

Respiration is a chemical reaction which occurs in all living cells, releasing energy from glucose.

Breathing is also called 'ventilation' and is the movement of gases into and out from the lungs.

Anaerobic respiration occurs without oxygen and releases less energy but more quickly than aerobic respiration.

Lactic acid is the waste product produced during anaerobic respiration.

The circulatory system is the heart and all the blood vessels in the body which carry cells and substances to all its parts.

The gas exchange system is the parts of the body involved in breathing, such as the lungs, airways and diaphragm. Different conditions and activities affect this system.

Cells get the energy they need from glucose during respiration. Watch a visual explanation of glucose.

Photosynthesis is a chemical reaction that takes place inside a plant, producing food for the plant to survive.

Photosynthesis and respiration are processes that allow plants to make food and release energy.

Temperature, light intensity and carbon dioxide are just some of the factors that affect photosynthesis. These factors can be manipulated to maximise growth.

Try this experiment and use pondweed to see how light intensity affects the rate of photosynthesis.

The maximum amount of air you can breathe in and out is your vital lung capacity. This experiment shows how this can be measured.