7.2 Organisation of Ecosystems

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 feed 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 consumer.

Question 15

What is a predator?

Answer 15

A consumer that kills and eats other animals.

Question 16

What is 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 number of predators and prey rise and fall in cycles

Question 18

Why are producers the trophic levels?

Answer 18

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

Bell 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

How is arithmetic mean calculated?

Answer 22

Sum of each number of each organism/the total number of each type.

Question 23

When considering the abundance of organisms. what is meant by the median?

Answer 23

The organism that represents the middle value when the number of each organism are arranged from lowest to higher.

Question 24

When considering the abundance of organisms. what is meant by the mode?

Answer 24

The most populous organisms

Question 25

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

Answer 25

• Organisms take in elements from their surrounding e.g. soil, air
• Elements converted to complex molecules which becomes biomass
• Elements transferred along food chains
• Elements returned to environment during excretion and decomposition of dead animals

Question 26

Give 3 molecules which are cycled through ecosystems.

Answer 26

Oxygen, carbon dioxide and water.

Question 27

Describe the carbon cycle

Answer 27

• 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 28

Why is the carbon cycle important?

Answer 28

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

Question 29

Describe the water cycle.

Answer 29

• Water from lakes and oceans evaporates
• The evaporated water condenses into clouds and returns to the 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 30

Why is the water cycle important?

Answer 30

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

Question 31

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

Answer 31

Microorganisms (bacteria and fungi) return carbon to the environment by releasing carbon dioxide through reparation while they decompose dead matter. The decomposition of dead matter in soil returns mineral ions to the environment for other organisms to use e.g. plants use mineral ions for growth.

Question 32

How can different temperatures be bad for certain communities?

Answer 32

• If the temperature is too low, growth will be slower as organisms will use more energy to stay warm.
• If the temperature is too high, organisms can die and water will become limited as evaporation increase

Question 33

What detrimental impacts can sulfur dioxide have on the environment?

Answer 33

• Formed when fossil fuels containing impurities are burnt
• Sulfur dioxide can dissolve in water to form acid rain which can erode buildings an pollute water sources

Question 34

What is detrimental impacts can carbon monoxide have on the environment’s?

Answer 34

• Carbon monoxide is formed from the incomplete combustion of fossil fuels.
• Carbon monoxide binds irreversibly to haemoglobin which prevents it from carrying oxygen
• Too much exposure can cause unconsciousness and death

Question 35

Name 5 greenhouse gases

Answer 35

• Water vapour
• Carbon dioxide
• Nitrous oxide
• Methane
• CFCs

Question 36

Give 3 human activities that contribute to greenhouse gases.

Answer 36

• Burning fossil fuels
• Deforestation
• Large scale livestock farming

Question 37

How do greenhouse gases lead to global warming?

Answer 37

• Greenhouse gases allow heat from the sun to enter the atmosphere.
• The gases act as a blanket and tray heat in the atmosphere.

Question 38

State 3 negative consequences of global warming

Answer 38

• Sea level rise caused by melting icebergs.
• Disrupted farming and agriculture
• Increased spread of diseases in warmer climates