Cells, organ systems and ecosystems

All living things are made of cells which are differentiated to perform different functions. Substances move into or out of the cell and enzymes are catalysts contributing to cell metabolism.

Respiration is a chemical reaction which releases energy from food. The respiratory system exchanges the gases which are involved in respiration.

We should eat a balanced diet suitable for our age and lifestyle. Overeating can lead to obesity. Nutrients have to be digested before we can absorb and use them.

The proper functioning of the circulatory system is essential for health. Blood transports substances around the body to every cell and removes toxic waste. It also defends against disease.

Plants adapt in order to efficiently collect raw materials required for photosynthesis. These raw materials must be transported through the plant and various factors can affect the rate of movement.

Plants carry out photosynthesis to make food from the raw materials they gather from their environment. We can investigate the conditions needed for this process and the factors which affect its rate.

Food chains and webs show the transfer of energy between trophic levels. They can be represented as pyramids of number and biomass and the efficiency of these transfers can be calculated.

Pollution can have a significant effect on the environment. Humans introduce chemicals to the environment which can enter food chains, causing problems like bioaccumulation and eutrophication.