B2 - Flashcards in GCSE Biology

Describe how energy is lost from food chains

Respiration, egestion, excretion

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Explain why pyramids of biomass and energy can be different shapes

Pyramids of biomass will look different to numbers if producers are large and if a small parasite lives on a large animal

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Describe how plants obtain nitrogen from the soil

They take in nitrogen as nitrates from the soil

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Describe the role of decomposers in the carbon and nitrogen cycles

They break down nitrogen compounds in dead organisms and return it to the soil

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Explain the difference between parasitism and mutualism

Parasitism: Parasites are organisms that live on or in a host organism. The parasite benefits from this arrangement, but the host suffers as a result | Mutualism: Both species benefit from their relationship

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Explain some adaptations that animals have for cold conditions

They have excellent insulation to prevent heat loss, such as fur and fat, some migrate to warmer areas, some hibernate, have a counter-current heat exchange, have anti-freeze proteins in their cells

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Explain some adaptations that animals have for dry conditions

Increase heat loss by having very little hair, they pant, lick their fur, seek shade, produce very concentrated urine, plants have deep roots, have large surface area to volume ratio

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Use Darwin's theory of natural selection to explain how evolution occurs

individuals in a species show a wide range of variation, individuals with characteristics most suited to the environment are more likely to survive and reproduce, the genes that allow these individuals to be successful are passed to their offspring

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State why Darwins theory was not well accepted by many people

It conflicted with religious views that God had made all the animals and plants on Earth and he did not make enough evidence at the time to convince many scientists

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Explain why it is considered important to set up conservation programmes

It can protect our food supply, prevent any damage to food chains, protect plants and animals which might be useful for medical uses and protect organisms and habitats people enjoy to visit and study

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Explain what sustainable development means

Taking enough resources from the environment for current needs, while leaving enough for the future.

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Describe the difference between an artificial and natural classification system

Artificial: Using obvious differences in features so that the organism can be identified | Natural: Based on evolutionary relationships

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Explain why different organisms have similar features

Because they may be closely related or have evolved to live in similar enviroments

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Describe the problems involved in constructing pyramids of biomass

Some organsisms feed on other organisms from different trophic levels and measuring dry mass involves removing all water from an organism which will kill it.

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Explain why food chains always have limited number of trophic levels

Not all of the energy available to organisms at one stage can be absorbed by organisms at the next one. The amount of available energy decreases from one stage to the next.

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Recall the roles of all four types of bacteria in the nitrogen cycle

Decomposers: Convert proteins and urea into ammonia | Nitrifying bacteria covert ammonia to nitrates | Denitrying bacteria: Convert nitrates to nitrogen gas | Nitrogen-fixing bacteria: Fix nitrogen gas

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Describe how oceans can act as carbon sinks

They absorb carbon dioxide, marine animals make shells from carbonate, which becomes limestone rock.

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Explain why the peak in numbers of predators and prey do not coincide

This is because it takes a while for the increased supply of food to allow more predators to survive and reproduce

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Explain what is meant by an ecological niche

The role of an organism within an ecosytem

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Explain why animals in colder climates tend to be larger

It helps decrease heat loss by decreasing the surface area to volume ratio

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Describe the differences between specialists and generalists

Specialists: Organisms that are well adapted to live in specific habitats | Generalists: Organisms can survive well in a range of different conditions

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Explain the difference between Lamarck's and Darwin's theory

Larmarck's: Any feature of an organism that is improved through its lifetime is passed to its offspring | Darwin: A specific gene mutation or a gene from a variety works well and gets passed on

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Recall the advantages and disadvantages of using indicator species to judge pollution levels

Advantages: Cheap, does not require equipment, monitors pollution over long period of time | Disadvantage: It isn't a direct method so can't give accurate results/measures at a specific time

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Explain why people in different countries have different carbon footprints

Developed countries uses the most fossil fuels.

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Explain the importance of genetic variation in species

If there is a change in the environment where the species lives, some members of the species may die, but that variation might allow others to survive

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Describe some of the difficulties in trying to protect whales

It is difficult to police international agreements on whaling and some countries want to lift the ban on whaling.

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B2

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