B17. Organising 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

Question 5

Define biomass

Answer 5

The total mass of living material

Question 6

Describe a simple food chain

Answer 6

producer ➡ primary consumer ➡ secondary consumer ➡ tertiary consumer

Question 7

What is a producer

Answer 7

An organisms that makes its own food

Question 8

What types of organisms are primary producers?

Answer 8

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

Question 9

What is a primary consumer?

Answer 9

An organism that feeds on producers

Question 10

What is a secondary consumer?

Answer 10

An organism that feeds on primary consumers

Question 11

What is a tertiary consumer?

Answer 11

An organisms that feeds on secondary consumers

Question 12

What is a predator?

Answer 12

A consumer that kills and eats other animals

Question 13

What is prey?

Answer 13

An animal that is killed and eaten by another animal

Question 14

Describe the pattern of predators and prey in a stable community

Answer 14

The numbers of predators and prey rise and fall in cycles

Question 15

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

Answer 15

Organisms take in elements from their surroundings
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 16

Give 3 molecules which are cycled through ecosystems

Answer 16

Oxygen, carbon dioxide and water

Question 17

Describe the carbon cycle?

Answer 17

Plants fix carbon dioxide into organic molecules during photosynthesis
The organic carbon-containing molecules are passed onto organisms that eat the plants
Carbon dioxide is released back into the atmosphere by respiration from animals and plants
Burning fossil fuels also releases carbon dioxide into the atmosphere

Question 18

Why is the carbon cycle important

Answer 18

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

Question 19

Describe the water cycle

Answer 19

Water from lakes and oceans evaporates
The evaporated water condenses into clouds and returns to earth as precipitation
The water from precipitation is useful for life on land
The water then returns to rivers and oceans through surface runoff

Question 20

Why is the water cycle important?

Answer 20

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

Question 21

Why is microorganisms important for the cycling of materials through an ecosystem?

Answer 21

Microorganisms return carbon to the environment by releasing carbon dioxide through respiration while they decompose dead matter. The decomposition of dead matter in soil returns mineral ions to the environment for other organisms to use

Question 22

What is meant by decomposition?

Answer 22

The breakdown of dead materials into simpler organic matter

Question 23

How do decomposers break down dead matter?

Answer 23

Decomposers release enzymes which catalyse the breakdown of dead material into smaller molecules

Question 24

What are the two types of decomposition?

Answer 24

Aerobic decomposition

Anaerobic decomposition

Question 25

What factors affect the rate of decomposition?

Answer 25

Oxygen availability
Temperature
Water content

Question 26

Why is oxygen required for decomposition?

Answer 26

Most decomposers require oxygen for aerobic respiration

Question 27

How does the availability of oxygen affect the rate of decomposition?

Answer 27

As oxygen levels increase the rate of decomposition increases.

As oxygen levels decrease, the rate of decomposition decreases

Question 28

Why can decomposition still occur in the absence of oxygen?

Answer 28

Some decomposers respire anaerobically

Question 29

How does soil water content affect the rate of decomposition?

Answer 29

Decomposers require water to survive:

In moist conditions the rate of decomposition is high

In waterlogged soils there is little oxygen for respiration so the rate of decomposition decreases

Question 30

Why does decomposition require water?

Answer 30

Water is required for the secretion of enzymes and absorption of dissolved molecules

Question 31

How does the temperature affect the rate of decomposition?

Answer 31

Rate highest at 50°C

Lower temperatures, enzymes work too slowly, rate decreases
High temperatures, enzymes denature, decomposition stops

Question 32

How is the rate of change calculated when considering the decay of biological material?

Answer 32

Rate of change = change in value ÷ change in time

Question 33

What is compost?

Answer 33

The nutrient-rich product of the rapid decay of waste biological material in optimum conditions set by gardeners and farmers

Question 34

How is compost used?

Answer 34

Used a natural fertiliser to promote growth of crops or garden plants

Question 35

Describe how biogas generators work

Answer 35

Biogas generators provide methane gas for fuel through anaerobic decomposition that occurs in animal waste