7. Ecology 2

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 alagae 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 comsumers .

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 prey ?

Answer 16

An animal that is killed an 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 fal 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 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

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

How is the arithmetic mean calculated?

Answer 22

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

Question 23

When considering the abundance of different organisms, what is meant by the term “mode”?

Answer 23

The most populous organism

Question 24

When considering the abundance of organisms , what is meant by the term “median” ?

Answer 24

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

Question 25

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

Answer 25

• 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 26

Give 3 molecules which are cycled through ecosystems

Answer 26

Oxygen , carbon dioxide and water.

Question 27

Describe the carbon cycle

Answer 27

-The carbon cycle starts with carbon dioxide in the atmosphere
- carbon then enters the carbon cycle by photosynthesis
- carbon dioxide returns back to the atmosphere by aerobic respiration

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 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 continous 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 respiration 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 increases

Question 33

How can changes in water levels affect ecosystems ?

Answer 33

• Animals may have to migrate to find water.
• Melting ice caps may destroy the habitats of some animals (either animals living in icy regions or by sea level rise).

Question 34

How can atmospheric gases affect ecosystems?

Answer 34

• Some organisms cannot survive when certain gases are present
• Polluted water can cause illnessto animals that drink it

Question 35

What detrimental impacts can sulfur dioxide have on the environment ?

Answer 35

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

Question 36

What detrimental impacts can carbon monoxide have on the environment ?

Answer 36

• 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 37

Name 5 greenhouse gases

Answer 37

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

Question 38

Give 3 human activities that contribute to greenhouse gases

Answer 38

• Burning fossil fuels
• Deforestation
• Large scale livestock farming

Question 39

How do greenhouse gases lead to global warming ?

Answer 39

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

Question 40

State 3 negative consequences of global warming

Answer 40

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