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Cells, organ systems and ecosystems

Variation, homeostasis and micro-organisms

  • Classification and biodiversity – WJEC

    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.

  • Cell division and stem cells – WJEC

    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.

  • DNA and inheritance – WJEC

    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 – WJEC

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

  • Mutation – WJEC

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

  • Evolution – WJEC

    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?

  • The nervous system – WJEC

    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.

  • 91Èȱ¬ostasis – WJEC

    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.

  • The role of the kidneys in homeostasis – WJEC

    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.

  • Micro-organisms and their applications – WJEC

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

  • Disease, defence and treatment – WJEC

    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?

Practical skills

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