This topic explores the definition of health and the distinction between communicable and non-communicable diseases, including the role of pathogens. It covers human and plant defence mechanisms, the development of medicines, and the impact of lifestyle factors on non-communicable diseases.
Topic 8 – Exchange and transport in animals explores how organisms obtain essential substances like oxygen and nutrients and remove waste products. In single-celled organisms, diffusion alone is sufficient, but larger animals require specialised exchange surfaces and transport systems. This topic covers the structure and function of the circulatory system, including the heart, blood vessels, and blood, as well as the mechanisms of gas exchange in the lungs and at the tissues.
Understanding exchange and transport is crucial because it explains how cells receive what they need to function and how waste is removed. This knowledge links to topics like respiration, digestion, and homeostasis. In exams, you'll be expected to explain adaptations of exchange surfaces, describe the double circulatory system, and interpret data on heart rate and gas exchange.
Mastering this topic helps you appreciate how the body maintains a stable internal environment. It also provides a foundation for understanding diseases like coronary heart disease and the effects of lifestyle choices on health. Practical skills include dissecting hearts, measuring lung volumes, and investigating the effect of exercise on pulse rate.
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