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B1 Topic 3 Problems of, and solutions to a changing environment
Drugs

A drug is a chemical substance that changes the way in which the body works, including our behaviour. Some
drugs particularly affect the central nervous system and change our psychological behaviour.
There are different types of drugs:
o…

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Short term effects

Alcohol slows down reactions because it is a depressant.
Being drunk can lead to blurred vision (making it more difficult to do simple tasks) and can lower inhibitions ­
people may do things they normally wouldn't.
The more alcohol in the body the slower the nervous system…

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o Animal vectors: These are animals that spread disease. Examples are the mosquito which carries the
protozoan that causes malaria. It bites other organisms to spread it. House flies can carry the
bacterium that causes dysentery. It spreads the disease by carrying the bacterium onto food.

Physical and Chemical barriers…

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o Antibacterials: Antibacterial antibiotics are used to treat bacterial infections. They work by killing
bacteria or stopping them from growing. However, bacteria can evolve resistance to the antibiotic,
meaning it doesn't work anymore.
o Antifungals: Antifungal antibiotics such as nystatin are used to treat fungal infections. They work by
killing…

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Biomass is how much the creatures at each level of a food chain would weigh if you put them together. This
biomass is a store of energy ­ so a pyramid of biomass shows how much energy there is at each stage in the
food chain.

In this pyramid of…

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An indicator species is an organism whose presence, absences or abundance reflects a specific
environmental condition.
Indicator species can signal a change in the biological condition of a particular ecosystem and thus may be
used to diagnose the health of an ecosystem.
For example, plants or lichens sensitive to heavy…

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Nutrients are constantly recycled

Living things are made of elements they take from the world around them. Plants not only take carbon from
the environment but also take oxygen, hydrogen and nitrogen from the soil or air. These elements are
formed into complex compounds that make up living organisms.
The…

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Decomposer bacteria turn the proteins and urea in dead plants and animals and waste into ammonia. This
ammonia can be converted into nitrites and then nitrates by nitrifying bacteria. As nitrates can be absorbed
by plants, the nitrogen in these organisms is recycled.
Some nitrogen-fixing bacteria live in the soil.…

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"mega-growth mega-death mega-decay"

Human activity and the Environment

Rapidly growing population

The population of the world is growing exponentially which means it is growing very quickly.
This is mostly due to modern medicine, making people live longer and more babies to survive at birth. It is
also due to modern…

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