Ecology and the environment

Question 1

define population

Answer 1

organisms of the same species in an area

Question 2

define community

Answer 2

different species living and interacting in an area

Question 3

define habitat

Answer 3

the place where an organism lives

Question 4

define ecosystem

Answer 4

the community of living organisms and their interactions with the environment

Question 5

abiotic factors

Answer 5

• light intensity
• temperature
• moisture levels
• soil pH and mineral content

Question 6

Affect of light intensity (abiotic)

Answer 6

• light requires for photosynthesis
• rate of photosynthesis affects rate which plant grows
• plants can be food sources or shelter for many organisms

Question 7

affect of temperature (abiotic)

Answer 7

affects rate of photosynthesis

Question 8

affect of moisture levels (abiotic)

Answer 8

both plants and animals need water to survive

Question 9

affect of soil pH and mineral content

Answer 9

• soil pH affects rate of decay, how fast mineral ions return to soil
• different species of plants thrive in different nutrient concentration levels

Question 10

biotic factors

Answer 10

• food availability
• new predators
• new pathogens
• competition

Question 11

affects of food availability (biotic)

Answer 11

• more food, organisms can breed more successfully
• population can increase in numbers

Question 12

affects of new pathogens

Answer 12

• when new pathogens arises, population has no resistance to it
• so they can be wiped out quickly

Question 13

affects of competition

Answer 13

•if one species is better adapted than other, it will outcompete other species
• reduces population of less adapted species

Question 14

Define trophic levels

Answer 14

the feeding levels in a food chain

Question 15

define producers

Answer 15

organisms that make their own food by photosynthesis

Question 16

define primary consumers

Answer 16

herbivores that only eat plants

Question 17

define secondary consumers

Answer 17

carnivores that eat primary consumers

Question 18

define tertiary consumers

Answer 18

• carnivores that eat secondary consumers
• have no predators
• called apex predators

Question 19

define decomposers

Answer 19

• bacteria and fungi that break down dead animals’ bodies and waste for energy
• using enzymes

Question 20

what do food chains show

Answer 20

• the feeding relationships between organisms
• organized by trophic levels

Question 21

what do food webs show

Answer 21

• collection of different food chains
• show how all organisms in a habitat interact
• shows independence, shows how population number changes can affect entire ecosystem

Question 22

what do pyramids of numbers show

Answer 22

• population of each organism at each trophic levels of food chain
• producers at bottom
• bars usually smaller further up you go

Question 23

what do pyramids of biomass show

Answer 23

• show relative biomass at each trophic level
• shows relative dry mass of material at each level
• less biomass as you move up

Question 24

How much energy is transferred from one trophic level to the other

Answer 24

about 10%

Question 25

why is only 10% energy transferred from one trophic level to the other

Answer 25

• not all biomass can be eaten
○ cannot eat bone, hooves, claws and teeth
• not all biomass eaten is converted into biomass of animal eating it
○ lots of glucose used in respiration, produces CO²
○ urea is waste substance released in urine
○ biomass consumed can be lost as faeces

Question 26

name and describe stages of carbon cycle

Answer 26

RESPIRATION
• plants + animals aerobically respire releases CO² in air
• decomposer respire while they break down compounds

PHOTOSYNTHESIS
• plants remove CO² from air through photosynthesis

DECOMPOSITION
• dead plants + animals broken down by decomposers
• carbon is returned into atmosphere

COMBUSTION
• when plants and fossil fuels are burnt, CO² is released into atmosphere

Question 27

biological consequences of pollution of air by sulphur dioxide

Answer 27

• released when fossil fuels burnt
• dissolves in water droplets in clouds
• creates acid rain
• makes rivers too acidic, leads to organisms dying
• corrodes metals and limestone in buildings
• leeches minerals out of soil so plants and trees cannot survive

Question 28

biological consequences of pollution by carbon monoxide

Answer 28

• released when fossil fuels burnt through incomplete combustion
• binds to hemoglobin, prevents red blood cells transporting oxygen around body
• can lead to tiredness, unconscious or death

Question 29

define greenhouse gases

Answer 29

• gases that absorb infrared radiation from the sun, trapping it above earth’s surface
• leads to increase of earth’s temperature

Question 30

Greenhouse gases and their sources

Answer 30

water vapor - rivers, lakes
CO² - deforestation, fossil fuels
Nitrous oxides - fertilizers, engines of vehicles
methane - cattle, rice paddy fields
CFC - refrigerators, aerosol sprays

Question 31

Effects of global warming

Answer 31

• climate change
• water levels rise - glaciers melt
• loss of habitats
• inhabitants environments, some species will become extinct or migrate

Question 32

Explain pollution of water by sewage

Answer 32

• sewage is rich in minerals and nutrients, allows decomposers and algae to thrive
• decomposers respire aerobically to break down sewage
• sewage may contian bacteria that also retire aerobically
• Algae bloom stops light reaching aquatic plants, causing them to die
• Lead to oxygen depletion, other aquatic organisms will die
• In sewage treatment works, alot of oxygen provided by stirring waste of injecting jets

Question 33

Define eutrophication

Answer 33

when fertilizers are washed off from the land into nearby rivers and lakes by rain

Question 34

Biological consequences of eutrophication caused by reached minerals from fertiliser

Answer 34

• the excess nutrients washed into the lakes from eutrophication encourages rapid growth of algae
• algae blocks sunlight reaching plants below, so they cannot photosynthesise
• leads to oxygen deprivation