Habitat DestructionCambridge IGCSE Biology: Flashcards

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Define biodiversity.

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Define biodiversity.: The number of different species that live in an area.
Name four reasons humans destroy habitats.: Increased area for housing, crop plant production, livestock production, and extraction of natural resources (or pollution).
How does habitat destruction disrupt food webs?: Removing a habitat removes the species living there, breaking feeding links and causing knock-on population changes across the whole food web.
Name three undesirable effects of deforestation.: Reduced biodiversity, extinction, and loss of soil (or flooding, or increased atmospheric CO2).
Why does deforestation increase atmospheric CO2?: Fewer trees remove less CO2 by photosynthesis, and burning cleared vegetation releases stored carbon directly.
Why does deforestation increase the risk of flooding?: Fewer trees means less water is intercepted and absorbed, so surface run-off increases.
Why does deforestation increase soil loss?: Without tree roots to bind it, soil is eroded more easily by wind and rain.
Name five causes of species becoming endangered or extinct.: Climate change, habitat destruction, hunting, overharvesting, pollution and introduced species.
How does habitat destruction reduce genetic variation in a population?: Shrinking habitat area reduces population size, which reduces the amount of genetic variation within the remaining population.
Why is reduced genetic variation dangerous for a population's survival?: It makes the population less able to survive further environmental change or disease, increasing extinction risk.
Name four ways endangered species can be conserved.: Monitoring and protecting species/habitats, education, captive breeding programmes, and seed banks.
Give an example of resource extraction that destroys habitats.: Mining, quarrying or logging.
How can marine pollution destroy a habitat without physically removing it?: Pollutants contaminate the water, harming or killing the organisms that live there even though the physical space remains.
Why can clearing land for livestock reduce biodiversity?: It replaces a natural habitat supporting many species with land used to support one type of animal, removing the original species' habitat.
What is the relationship between habitat destruction and food web disruption?: Destroying a habitat removes species from it, breaking feeding links and disrupting the food web for other connected species too.