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5 Cards in this Set
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Infectious diseases are caused by the transmission of pathogens, which are microorganisms such as bacteria and viruses. Pathogens can be transmitted by direct contact - horizontal and vertical transmission - and by indirect contact - vehicle-borne transmission and vector-borne transmission. |
Parasites are organisms that live on or in a host organism. The parasite benefits from this arrangement, but the host suffers as a result. Fleas are examples of parasites. They live on the skin of other animals and suck their blood: this feeds the flea but weakens the host. |
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Drugs are chemicals that cause changes in the body. They can be divided into legal and illegal drugs. Drugs can also be medical (drugs taken to cure illness) or recreational (drugs taken because they have pleasing effects). Some drugs can be addictive – more and more is needed to achieve the same effect. Drugs can be separated into categories – solvents, painkillers, depressants and stimulants. |
Some organisms rely on the presence of organisms of a different species. For example, oxpecker birds eat ticks and larvae infesting the skin of buffalo and other large animals. For this reason oxpeckers are called a cleaner species. This is an example of mutualism - both species benefit from the arrangement. |
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Food chains show the feeding relationships in a habitat. Pyramids of biomass are charts that show the mass of living organisms at each step in a food chain. Energy is lost moving up in a food chain, and this limits the length of the chain. Parasites live off a host organism. Mutualism is where species work together for mutual benefit. |
Antibiotics are substances that kill bacteria or stop their growth. They do not work against viruses: it is difficult to develop drugs that kill viruses without also damaging the body’s tissues.Antifungal agents kill fungi. An example of an antifungal is nyastatin which treats the fungus candida albicans. |
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Human beings compete with other living things for resources and space. As the world’s population continues to increase, and standards of living improve, there is serious danger of a permanent change to the global environment.Human activities have led to the pollution of the environment, particularly in water and the air. Eutrophication is one example of this. |
Smoking is very harmful to health. It causes around 80 per cent of deaths fromlung cancer, bronchitis andemphysema in the UK, and almost a fifth of UK deaths from heart disease. |
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The Earth’s resources are limited and it is important that we conserve as much as possible. One way to do this is to recycle waste products. Some forms of recycling happen in nature: the carbon cycle and nitrogen cycle allow these elements to be recycled. |
Biomass is food for the next trophic level in a food chain.It can also be used as a source of renewable energy, to reduce our dependence on fossil fuels, and to help reduce air pollution. Using biomass as fuel still puts carbon dioxide back into the atmosphere, but it's the same carbon dioxide taken from the air as the biomass was produced. The use of biomass for energy production is carbon neutral. |
