1. how species depend on each other
1.1. A species is a group of organisms that can breed together to produce fertile offspring
1.2. Adaptations are features that help an organism survive in the environment it lives in.
1.3. classfication
1.3.1. scientist and differences between living things on Earth are used to put them into groups. This process is called classification.
1.4. food matters
1.4.1. A food web is simply a number of food chains joined together. It shows how the loss of one organism has an effect of other organisms in the food web. This is called the interdependence of living things.
1.5. extiction
1.5.1. Living organisms are dependent on the environment and other species for their survival. When the environment changes, organisms are not as well adapted to it. Individuals that are poorly adapted to their environment are less likely to survive and reproduce than those that are well adapted. Similarly, it is possible that a species that is poorly adapted to its environment will become extinct.
1.5.2. Here are some factors that can cause a species to become extinct: rapid changes to the environment, such as the climate new diseases new predators new competitors
1.6. carbon cycle
1.6.1. Removing carbon dioxide from the atmosphere:, green plants remove carbon dioxide from the atmosphere by photosynthesis. Organisms return carbon dioxide to the atmosphere by respiration. It is not just animals that respire. Plants and microorganisms do, too. Passing carbon from one organism to the next: When an animal eats a plant, carbon from the plant becomes part of the fats and proteins in the animal. Microorganisms and some animals feed on waste material from animals, and the remains of dead animals and plants. The carbon then becomes part of these microorganisms and detritus feeders.
1.7. the sun
1.7.1. By the process of photosynthesis, organic compounds like glucose are made from carbon dioxide and water using this energy. Plants only absorb a small percentage of the Sun’s energy for the process of photosynthesis. The energy is absorbed in chemicals that make up the plants’ cells.
1.7.2. Animals cannot make their own food so they have to eat. This is one way in which energy is transferred between organisms in an ecosystem. The energy is used for a number of life processes. In a food chain only around 10 per cent of the energy is passed on to the next level. The rest of the energy passes out of the food chain in a number of ways: via heat energy is used for life processes (for example movement) uneaten parts that pass to decomposers is excreted and passes to decomposers
1.8. nitrogen cycle
1.8.1. Nitrogen fixation Making nitrogen compounds from nitrogen in the air is called nitrogen fixation.
1.8.2. Nitrogen compounds Nitrogen compounds in living things are returned to the soil through: excretion and egestion by animals the decay of dead plants and animals. As a result of these processes, nitrogen is cycled continually through the air, soil and living things. This is called ‘the nitrogen cycle’.
2. the importance of biodiversity
2.1. Classification at different levels Organisms are classified into different groups. This classification is done according to similarities and differences in characteristics including: physical features DNA. Organisms are classified at different levels. These levels can be arranged in an order, progressing from: a large group containing many organisms with a small number of characteristics in common, such as a kingdom a small group containing fewer organisms with more characteristics in common, such as a species. This classification of both living and fossil organisms helps scientists to make sense of the diversity of organisms on Earth, as well as to suggest evolutionary relationships between them.
2.2. biodiversity
2.2.1. Biodiversity means having as wide a range of different species as possible. Maintaining biodiversity is an important part of using the environment in a sustainable way. Indiscriminate use of the environment, for example cutting down large areas of the rain forest to grow crops such as soya, results in a large number of species becoming extinct and reduces biodiversity
2.2.2. Monoculture Monoculture is the continuous production of one type of crop that is often genetically uniform. Doing this in a large field means harvesting by machinery can be done efficiently. There are disadvantages to monoculture. If pests and disease attacked the crop it could harm it easily, so farmers use a lot of chemical pesticides. This can harm the environment and so is not viewed as sustainable. Using large fields and pesticides reduces the variety of species. This hinders biodiversity. Another disadvantage is that if a natural disaster were to occur, the whole crop could be wiped out.
2.2.3. Improving sustainability Packaging can be a major environmental problem. The use of biodegradable packaging is an option to tackle this problem. When put in a landfill site it should decompose quickly, unlike a lot of currently used packaging. However, to decompose in a way that only produces carbon dioxide oxygen needs to be present, but in landfill oxygen is often not present. This results in the production of a powerful greenhouse gasmethane being produced if decay occurs at all. Another possible solution is to recycle the packaging. The materials and energy used in production, energy used in transport and pollution created are all considerations when trying to improve sustainability.
3. mutations
3.1. Causes and effects Mutations are changes that can occur in genes. These changes are random and can be caused by background radiation and chemicals that we come into contact with Sometimes these changes can be so severe that the cell dies, sometimes the cell can divide uncontrollably and become cancerous, and sometimes the changes are small and the cell survives. Very rarely the changes may even be beneficial to us and produce new and useful characteristic
3.2. Passing on mutations If these changes occur in normal body cells, the changes are lost when we die. But if the changes occur in our sex cells such as sperm and ova, there is the possibility that the changes in the gene will be passed onto the next generatioIf these changes occur in normal body cells, the changes are lost when we die. But if the changes occur in our sex cells such as sperm and ova, there is the possibility that the changes in the gene will be passed onto the next generation.
4. theory of evolution
4.1. how do life start
4.1.1. the Earth is about 4,500 million years old there is evidence that living things existed on Earth at least 3,500 million years ago no one was there to record how life began early Earth was hotter and the atmosphere consisted mostly of carbon dioxide (with other gases such as ammonia and methane).
4.2. darwins theory
4.2.1. natural selection
4.2.1.1. The theory of evolution states that evolution happens by natural selection. Individuals that are poorly adapted to their environment are less likely to survive and reproduce. You need to remember that variation can be caused by both genes and the environment. But it is only variation caused by genes that can be passed on to the next generation.
4.3. selective breeding
4.3.1. Selective breeding is a process where we choose the characteristics we want in an animal or plant. We then breed together a male and female showing some of those characteristics. From the offspring produced we select those that show the characteristic the most, and breed them together. This process is repeated over many generations, each time selecting and breeding together those animals or plants that have the characteristics we are looking for.