Fuels from fermentation In India only animal waste is fed in (there are taboos against using human waste), this produces high quality gas but little amounts of fertiliser. Biogas can be produced on a large scale, or on a small scale. For example, a small biogas...
The kidneys Our bodies need to get rid of waste products. Three waste products our bodies must excrete are CO2, urea and sweat. This is known as homeostasis (controlling conditions inside the body). Liver Urea (a waste product from the breakdown of amino acids)...
B2.7 Cell Division and inheritance Summary Characteristics are passed on from one generation to the next in both plants and animals. Simple genetic diagrams can be used to show this. There are ethical considerations in treating genetic disorders. Genetic material In...
B2.8 Speciation Summary Changes in the environment of plants and animals may cause them to die out. The fossil record shows that new organisms arise, flourish, and after a time become extinct. The record also shows changes that lead to the formation of new species....
Diffusion Materials like oxygen, carbon dioxide and glucose enter and leave cells by diffusion. Diffusion occurs when particles spread. They move from a region where they are in high concentration to a region where they are in low concentration. Diffusion happens when...
B2.6 Respiration Summary Respiration in cells can take place aerobically or anaerobically. The energy released is used in a variety of ways. The human body needs to react to the increased demand for energy during exercise. Respiration Definition: The process of...
B2.5 Proteins Summary Proteins have many functions, both inside and outside the cells of living organisms. Proteins, as enzymes, are now used widely in the home and in industry. Protein structure Protein molecules are made up of long chains of amino acids. ...
B2.4 Organisms and their environment Summary Living organisms form communities, and we need to understand the relationships within and between these communities. These relationships are affected by external influences. Physical factors Physical factors that may affect...
B2.3 Photosynthesis Summary Green plants and algae use light energy to make their own food. They obtain the raw materials they need to make this food from the air and the soil. The conditions in which plants are grown can be changed to promote growth....
B2.1 Cells and Cell Structures Summary All living things are made up of cells. The structures of different types of cells are related to their functions. To get into or out of cells, dissolved substances have to cross the cell membranes. Cells...
B2.1 Tissues, Organs and Organ Systems Summary The cells of multicellular organisms may differentiate and become adapted for specific functions. Tissues are aggregations of similar cells; organs are aggregations of tissues performing specific...
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...