19.3 Ecosystems & Biodiversity (Cambridge (CIE) O Level Biology): Flashcards
Exam code: 5090
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Define population.
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Cards in this collection (24)
Define population.
A group of organisms of the same species living in the same place at the same time.
Define community.
All the populations of different species living in the same area at the same time.
Define habitat.
The place where an organism lives.
Define ecosystem.
A unit containing a community of organisms and their environment, interacting together.
What is meant by interdependence within a community?
Species depend on one another for food, shelter, pollination and so on, so removing one species can affect the whole community.
factors are the living components of an ecosystem, such as plants and animals.
Biotic factors are the living components of an ecosystem, such as plants and animals.
Give two examples of abiotic factors in an ecosystem.
Non-living factors include:
light intensity
water availability
mineral ions
True or False?
Abiotic factors are the non-living components of an ecosystem.
True.
Examples include light intensity, water availability and mineral ions.
What three things do all organisms compete with one another for?
Organisms compete for:
food
water
living space
The organisms best to their environment generally increase their populations at the expense of others.
The organisms best adapted to their environment generally increase their populations at the expense of others.
What four factors control population growth in most organisms?
Population growth is controlled by:
food supply
competition
predation
disease
True or False?
Predation is one of the factors that controls the growth of a population.
True.
Food supply, competition, predation and disease all control population growth.
Define biodiversity.
The number of different species that live in a particular area.
Why is high biodiversity important?
It is needed for stable ecosystems.
True or False?
Human activities have generally increased biodiversity.
False.
Human activities have tended to force biodiversity downwards.
What is the major human pressure that reduces biodiversity?
Habitat destruction
Clearing large areas of forest to make space for farming and housing is called .
Clearing large areas of forest to make space for farming and housing is called deforestation.
Why does clearing land for farming and housing destroy habitats?
A growing population needs more space for crops, livestock and homes, so habitats such as forests are cleared.
How does the extraction of natural resources destroy habitats?
Collecting wood, stone and metals (e.g. by mining) means forests and land must be cleared first.
How does eutrophication reduce biodiversity in waterways?
Fertiliser runoff leads to the loss of dissolved oxygen, so most aquatic species die.
Oil spills and other waste cause pollution, which kills sea life.
Oil spills and other waste cause marine pollution, which kills sea life.
True or False?
Destroying a habitat can cause species to die because their prey is lost.
True.
Habitat destruction interrupts food chains and webs, so species may die when their food source is gone.
Give two main reasons for habitat destruction by humans.
Reasons include:
clearing land for farming and housing
extraction of natural resources
marine pollution
Give one example of a habitat destroyed by the growing human population.
Rainforests (woodland and marine habitats are also affected).
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