Ecosystems

Question 1

Define habitat.

Answer 1

The area in which an organism lives.

Question 2

Define individual.

Answer 2

A single organism.

Question 3

Define population.

Answer 3

The total number of individuals that live in a habitat or ecosystem.

Question 4

Define community.

Answer 4

Living organisms interacting with one another.

Question 5

Define ecosystem.

Answer 5

Abiotic and biotic factors interacting with one another.

E.g. pond, coral reef.

Question 6

Define abiotic.

Answer 6

A non-living part of the ecosystem.

E.g. rocks, toxins, snowfall, water, sunlight.

Question 7

Define biotic.

Answer 7

A living part of the ecosystem.

E.g. animals, grass (producers).

Question 8

Define interdependence.

Answer 8

The way in which living organisms depend on each other to survive, grow and reproduce. The loss of one organism will has an effect on other organisms in a food chain/web.

Question 9

Explain interdependence by using a food chain.

Answer 9

Slugs, rabbits and insects all eat grass. If the population of slugs decreases then rabbits and insects will get more food - their population will increase. Thrushes, however, would have to eat more insects because of the decline of slugs. Therefore, the insect population could also go down. Voles and frogs also eat insects, if the insects’ population goes down then their population would go down too.

Question 10

What do plants compete for?

Answer 10

Space, water, light (and minerals).

Question 11

What do animals compete for?

Answer 11

Food, space, mates, water.

Question 12

Why could there be a lag between two lines in a graph?

Answer 12

The organisms need time to reproduce or decline in number.

Question 13

Define extremophile.

Answer 13

An organism that is adapted to living in conditions of extreme temperature, pressure or chemical concentration (salt, acid, alkali).
E.g. bacteria in gut (gut flora), polar bears.

Question 14

Choose and animal and name its adaptations.

Answer 14

Oryx - doesn’t sweat, wide feet don’t sink in sand, concentrated urine and dry faeces, large body heats up slowly, stands in the breeze t the top of sand dunes.

Question 15

Name types of producers.

Answer 15

Photosynthesis (sunlight), chemosynthesis (chemical reactions: sulphur).

Question 16

Create a food chain. What is the producer, primary consumer and secondary consumer.

Answer 16

grass → zebra → hyena
producer primary secondary
consumer consumer

Question 17

Explain food chains.

Answer 17

Level 1 - producers, aka primary producers, make own food, chemo/photosynthesis
Level 2 - primary consumers, herbivores, eat plants/algae
Level 3 - secondary consumers, carnivores that eat herbivores
Level 4 - tertiary consumers, carnivores that eat carnivores
Level 5 - quaternary consumers, level four

Question 18

What is a trophic level?

Answer 18

A stage in a food chain, feeding level.

Question 19

Define biomass.

Answer 19

The total mass of all living or non-living matter.

Question 20

Why are pyramids of biomass narrow at the top?

Answer 20

As we go up the trophic levels, we lose biomass in the food chain.

Question 21

List processes that increase the levels of carbon dioxide in the atmosphere.

Answer 21

Respiration, decomposition (decay), combustion

Question 22

List processes that decrease the levels of carbon dioxide in the atmosphere.

Answer 22

Photosynthesis (also carbon dioxide getting dissolved in the ocean)

Question 23

Why are decomposers important?

Answer 23

They break down dead trees and make space for new ones
They release nutrients locked up in trees back into the soil for new trees
They release carbon dioxide back into the air so trees can do photosynthesis

Question 24

What is the difference between decomposers and detritivores?

Answer 24

Decomposers - feed on dead biomass (e.g. dead plants/animals) and release enzymes from their cells onto the dead plants/animals and absorb the soluble nutrients. E.g. bacteria, fungi.
Detritivores - eat biomass, break it down with enzymes inside their body. E.g. millipede, earthworm.

Question 25

How can we help decomposers break down waste quickly for compost?

Answer 25

Temperature: 32-60°C
Oxygen: for respiration, turn over compost heap or add holes in container for aeration

Question 26

Why do plants grow better with compost?

Answer 26

Compost provides many essential nutrients for plant growth e.g. nitrogen, phosphorus, potassium (NPK)
Compost improves soil structure; the soil will hold the right amount of moisture, nutrients and air/oxygen.

Question 27

Define biodiversity.

Answer 27

The range/variety of organisms living in an ecosystem.

Question 28

Why is biodiversity important?

Answer 28

Each species has a particular function in the ecosystem. Some species can produce organic material, contribute to the nutritive system, control soil erosion. It helps create a stable ecosystem.

Question 29

Why is biodiversity on Earth decreasing?

Answer 29

Pollution, climate change, loss of habitat, overexploitation, killing of species.