7.2 Ecology (organisation of an ecosystem)

Question 1

Define population

Answer 1

a species that occupy the same habitat

Question 2

Define habitat

Answer 2

the place in which an organism lives

Question 3

Define community

Answer 3

Populations of different species interacting

Question 4

Define ecosystem

Answer 4

the interactions between the biotic and abiotic factors in an area

Question 5

What do food chains show?

Answer 5

food chains show the feeding relationships of different organisms and the flow of energy between the organisms

Question 6

Define biomass

Answer 6

the total mass of living material

Question 7

What are trophic levels

Answer 7

the stages in a food chain

Question 8

What do arrows in a food chain represent?

Answer 8

the direction of biomass transfer

Question 9

Describe a simple food chain

Answer 9

producer –> primary consumer –> secondary consumer –> tertiary consumer

Question 10

What is a producer?

Answer 10

an organism that makes its own food

Question 11

What types of organisms are primary producers?

Answer 11

photosynthetic organisms like green plants and algae that trap energy from the sun

Question 12

What is a primary consumer?

Answer 12

an organism that feeds on producers

Question 13

What is a secondary consumer?

Answer 13

an organism that feeds on primary consumers

Question 14

What is a tertiary consumer?

Answer 14

an organism that feeds on secondary consumers

Question 15

What is a predator?

Answer 15

a consumer that kills and eats other animals

Question 16

What is a prey?

Answer 16

an animal that is killed and eaten by another animal

Question 17

Describe the pattern of predators and prey in a stable community

Answer 17

the numbers of predators and prey rise and fall in cycles

Question 18

Why are producers the first trophic level?

Answer 18

• producers provide all biomass for the food chain (production of glucose via photosynthesis)
• the rest of the food chain involves the transfer of this biomass

Question 19

What piece of apparatus is used to measure the abundance and distribution of organisms in an area?

Answer 19

Quadrat

Question 20

What piece of apparatus is used to study the distribution of organisms across a gradient?

Answer 20

belt transect

Question 21

When considering the abundance of organisms, what is meant by the term ‘mean’?

Answer 21

the average number of organisms

Question 22

When considering the abundance of different organisms, what is meant by the term ‘mode’?

Answer 22

the most populous organism

Question 23

When considering the abundance of organisms, what is meant by the term ‘median’?

Answer 23

the organism that represents the middle value when the numbers of each organism are arranged from lowest to highest

Question 24

Describe how materials cycle through the living and non-living components of an ecosystem

Answer 24

• organisms take in elements from their surroundings. e.g. soil, air
• elements converted to complex molecules which become biomass
• elements transferred along food chains
• elements returned to environment during excretion and decomposition of dead organisms

Question 25

Give 3 molecules which are cycled through ecosystems

Answer 25

oxygen, carbon dioxide and water

Question 26

Describe the carbon cycle

Answer 26

1. plants fix carbon dioxide into organic molecules during photosynthesis
2. the organic carbon-containing molecules are passed onto organisms that eat the plants
3. carbon dioxide is released back into the atmosphere by respiration from animals and plants
4. burning fossil fuels also releases carbon dioxide into the atmosphere

Question 27

Why is the carbon cycle important?

Answer 27

carbon-containing molecules such as glucose are important for living organisms to grow and provide energy for vital functions within cells

Question 28

Describe the water cycle

Answer 28

1. water from lakes and oceans evaporates
2. the evaporated water condenses into clouds and returns to earth as precipitation
3. the water from precipitation is useful for life on land
4. the water then returns to rivers and oceans through surface runoff

Question 29

Why is the water cycle important

Answer 29

living organisms require water and the water cycle provides organisms on land with a continuous supply of water