B1.8 Evolution Summary Particular genes or accidental changes in the genes of plants or animals may give them characteristics which enable them to survive better. Over time this may result in entirely new species. There are different theories of evolution. Darwin’s...
B1.7 Genetic Variation and Its Control Summary There are not only differences between different species of plants and animals but also between individuals of the same species. These differences are due partly to the information in the cells they have inherited from...
B1.4 Interdependence and Adaptation Summary Organisms are well adapted to survive in their normal environment. Population size depends on a variety of factors including competition, predation, disease and human influences. Changes in the environment may affect the...
B1.5 Energy and biomass in food chains Summary By observing the numbers and sizes of the organisms in food chains we can find out what happens to energy and biomass as it passes along the food chain. Energy transfer Radiation from the Sun is the source of energy for...
B1.6 Waste materials from plants and animals Summary Many trees shed their leaves each year and most animals produce droppings at least once a day. All plants and animals eventually die. Microorganisms play an important part in decomposing this material so that it can...
B1.2 Nerves and Hormones Summary The nervous system and hormones enable us to respond to external changes. They also help us to control conditions inside our bodies. Hormones are used in some forms of contraception and in fertility treatments. Plants also produce...
B1.3 The Use and Abuse of Drugs Summary Drugs affect our body chemistry. Medical drugs are developed and tested before being used to relieve illness or disease. Drugs may also be used recreationally as people like the effect on the body. Some drugs are...
B 1.1.2 Infectious Disease Summary Our bodies provide an excellent environment for many microbes which can make us ill once they are inside us. Our bodies need to stop most microbes getting in and deal with any microbes which do get in. Vaccination can be used to...
B1.1.1 Diet and Exercise Summary A combination of a balanced diet and regular exercise is needed to help keep the body healthy. Healthy Diet A healthy diet contains the right balance of the different foods you need and the right amount of energy. These foods should...