Cambridge Lower Secondary Stage 8 Biology Flashcards

What is an ecosystem?

Topic: Ecosystems
Answer: An ecosystem is all the living organisms in an area together with the non-living conditions they interact with.

What is a habitat?

Topic: Ecosystems
Answer: A habitat is the place where an organism lives. It provides conditions and resources the organism needs.

How is a habitat different from an ecosystem?

Topic: Ecosystems
Answer: A habitat is a specific place where an organism lives; an ecosystem includes many organisms, habitats and non-living conditions interacting together.

Give four examples of ecosystems on Earth.

Topic: Ecosystems
Answer: Examples include forests, deserts, grasslands, ponds, rivers, oceans, coral reefs, tundra and wetlands.

Why can one ecosystem contain many habitats?

Topic: Ecosystems
Answer: Different parts of the ecosystem have different conditions, such as light, water, shelter, temperature and food availability.

Give examples of habitats within a forest ecosystem.

Topic: Ecosystems
Answer: Tree canopy, tree bark, leaf litter, soil, undergrowth and a stream inside the forest can all be habitats.

Give examples of habitats within a pond ecosystem.

Topic: Ecosystems
Answer: Open water, pond surface, muddy bottom, pond plants, stones and the pond edge can all be habitats.

Why do different organisms live in different habitats within the same ecosystem?

Topic: Ecosystems
Answer: Different organisms are adapted to different conditions and use different resources such as food, shelter, light and water.

What does habitat variety usually do for biodiversity?

Topic: Ecosystems
Answer: More habitat variety often supports greater biodiversity because more types of organisms can find suitable places to live.

A rocky shore has pools, dry rocks and seaweed areas. Why is it one ecosystem with many habitats?

Topic: Ecosystems
Answer: The areas interact as part of the shore ecosystem, but each area has different conditions and supports different organisms.

What is bioaccumulation?

Topic: Ecosystems
Answer: Bioaccumulation is the build-up of toxic substances in the bodies of organisms over time.

Why do some toxic substances bioaccumulate?

Topic: Ecosystems
Answer: Some toxins are not easily broken down or excreted, so they remain in tissues and increase in concentration over time.

How can a toxin enter an aquatic food chain?

Topic: Ecosystems
Answer: A toxin may enter water from pollution, be absorbed by producers or small organisms, and then pass to consumers when they feed.

Why are top predators often most affected by bioaccumulation?

Topic: Ecosystems
Answer: They eat many contaminated prey, so toxins from many organisms can build up to high levels in their bodies.

What is the difference between a small dose of toxin and a high body concentration caused by bioaccumulation?

Topic: Ecosystems
Answer: A small dose is one exposure; bioaccumulation means repeated exposure causes the toxin level inside an organism to build up over time.

Describe a possible effect of bioaccumulation on individual animals.

Topic: Ecosystems
Answer: It can poison animals, damage organs, reduce fertility, weaken them or cause death.

Describe a possible effect of bioaccumulation on a population.

Topic: Ecosystems
Answer: If many organisms die or cannot reproduce successfully, the population size may decrease.

How can bioaccumulation affect a whole ecosystem?

Topic: Ecosystems
Answer: It can reduce populations, disturb feeding relationships and change the balance of the ecosystem.

A lake contains toxic pesticide. Small invertebrates contain a little toxin. Large fish contain much more. Explain why.

Topic: Ecosystems
Answer: The fish eat many contaminated organisms, so toxin from each prey item builds up inside the fish.

Why can bioaccumulation harm organisms that were not directly exposed to the original pollution?

Topic: Ecosystems
Answer: Toxins can pass along food chains, so predators may be affected after eating contaminated prey.

What is a new species in an ecosystem?

Topic: Ecosystems
Answer: A new species is one that has recently arrived or been introduced into an ecosystem where it was not present before.

What is an invasive species?

Topic: Ecosystems
Answer: An invasive species is a new species that spreads and causes harm to native organisms, habitats or ecosystem balance.

Is every new species invasive? Explain your answer.

Topic: Ecosystems
Answer: No. A species is invasive only if it spreads and has harmful effects on other organisms or the ecosystem.

Why can an invasive species spread quickly in a new ecosystem?

Topic: Ecosystems
Answer: It may have few natural predators, reproduce quickly, tolerate the conditions well or outcompete native species.