Chapter 4 Ecosystems

Question 1

What is the difference between an ecosystem and a habitat?

Answer 1

A habitat is the place where an organism naturally lives. An ecosystem is made up of different habitats and is a network of interactions between all the living organisms and the non-living things around them.

Question 2

Explain why the food web cannot exist without the producers.

Answer 2

They provide food for the consumers in the web so without producers, the organisms in the other dependent trophic levels will not survive.

Question 3

What do the arrows in a food web represent?

Answer 3

The energy moving up the food chain.

Question 4

Describe two possible habitats in the desert ecosystem.

Answer 4

Termites live at the base of saguaro cactus stems.
Kangaroo rats live in burrows in the desert.
The desert ant lives underneath rocks and soil, and on the soil surface.

Question 5

What is bioaccumulation?

Answer 5

Gradual increase of a substance in an organism‘s body over its lifetime; it happens when the substance cannot be broken down inside the body cells.

Question 6

What is a native species?

Answer 6

Types of organisms that are living in their natural habitat.

Question 7

What is a predator?

Answer 7

An animal that preys on other animals.

Question 8

How do invasive species hurt the ecosystem?

Answer 8

They do not belong in the ecosystem and may disrupt the food chain by eating up food that other animals in the food chain need to survive. This may cause the extinction of native animal species.

Question 9

What are microplastics and why are they harmful?

Answer 9

Small pieces of plastic that are broken down from bigger pieces of plastic. They are non-biodegrable and will accumulate in the bodies of humans or animals.

Question 10

What is the difference between bioaccumulation and biomagnification?

Answer 10

Bioaccumulation is the gradual increase of a substance in an organism’s body, while biomagnification is the increase of concentration of a substance as you go up a food chain

Question 11

What is DDT?

Answer 11

It is an insecticide and so it kills insects.

Question 12

What is a herbivore?

Answer 12

An animal that only eats plants.

Question 13

How does DDT affect a food chain?

Answer 13

DDT is a persistent chemical and toxic to many animals. It can cause bioaccumulation in organisms’ bodies and biomagnification in a food chain, poisoning the organisms in the food chain.

Question 14

Give 2 examples of interactions between organisms in the desert that are not to do with feeding

Answer 14

• Plants provide places for animals to make nests
• Plant roots help to hold the soil together so that it does not wash away when it rains
• Animals help plants to reproduce by pollinating their flowers or spreading their seeds

Question 15

Explain what is meant by an ‘introduced species’?

Answer 15

A species of plants or animals that does not belong to an ecosystem but brought in to it.

Question 16

Give an example of an invasive species causing harm in an ecosystem.

Answer 16

• Water hyacinths introduced in Lake Victoria that multiplied so quickly that fishing boats cannot move through it.
• Stoats from Europe introduced to New Zealand to control rabbits but instead bred rapidly and ate native birds, causing their extinction.

Question 17

Why are some microplastics found in the mud at the bottom of the sea ?

Answer 17

They are accidentally taken into the bodies of living organisms when feeding / they also sink because they are denser than water

Question 18

Name some possible non-living things you can find in an ecosystem

Answer 18

• Light
• Temperature
• Soil
• Water
• Air

Question 19

What is a carnivore and an omnivore?

Answer 19

Carnivore: an animal that eats meat
Omnivore: an animal that eats both meat and plants

Question 20

Suggest why it is very difficult to eradicate an introduced species once it has settled into a new place?

Answer 20

They usually breed rapidly and have adapted well to the new place.