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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.

Biodiversity is the total number and variety of species in a given area. It can be studied using sampling techniques, and organisms can be classified according to morphological features.

Cells divide by mitosis for growth and repair. They divide by meiosis to produce gametes for sexual reproduction. Stem cells differentiate into specialised cells during the development of organisms.

What is DNA and how is the structure of this hereditary molecule responsible for its function? Scientists are using their knowledge of DNA to create and use genetic profiles.

Variation is the differences found within the same species. It can be caused by both sexual reproduction and environmental influences.

How can genes change? Mutations are caused by several factors and can cause genetic disorders. How can gene therapy help treat these disorders?

Evolution by natural selection was proposed as a theory by Darwin and Wallace. What evidence is there in the world today to suggest that species evolve by this mechanism?

Our nervous system allows us to detect and react to changes in the environment. Sense organs, like the eyes, detect changes and our central nervous system co-ordinates a response.

Conditions inside our body need to be maintained in a steady state. Blood sugar level and temperature are regulated carefully. Lifestyle choices such as drugs and alcohol can affect this homeostasis.

Our kidneys regulate the water concentration in our blood and excrete toxic waste. When they fail to work properly, dialysis treatment or a transplant is required.

Handling micro-organisms safely requires specific techniques. Growing and studying micro-organisms gives us vital information about their rapid growth and their possible uses.

Communicable diseases are caused by the spread of micro-organisms. How do they spread, and what future developments will come from the study of the immune system and the treatment of diseases?

Under the new GCSE specifications in Wales, practical work in Science will be examined. This unit will help students to prepare for the practical examination.