4) Ecology and the environment

Question 1

Population definition

Answer 1

A group of organisms of the same species living in the same place at the same time

Question 2

Community definition

Answer 2

All of the populations living in the same area at the same time

Question 3

Habitat definition

Answer 3

Where an organism lives

Question 4

Ecosystem definition

Answer 4

All the biotic factors and all the abiotic factors that interact within an area at one time

Question 5

Quadrat use

Answer 5

-square frames made of wood/ wire
-used to measure:
-number of an individual species
-species richness
-percentage cover

Question 6

Investigate population size in 2 different areas

Answer 6

1. Measure a survey area in your chosen habitat
2. Use a random number generator to create a set of coordinates to place a quadrat
3. Count the number of your chosen plant species that are found within this quadrat
4. Estimate the population
   Estimated population size = total area/ area sampled x total number of plants counted
5. Repeat with another area

Question 7

Biodiversity definition

Answer 7

The range and variety of different species of organisms on Earth, or within an ecosystem
-considers species richness, variation, distribution, population size

Question 8

Importance of biodiversity

Answer 8

-ensures stability of ecosystems by reducing the dependence of one species on another for food, shelter, maintenance of the physical environment
-populations are more likely to be resilient to sudden environmental impacts/ disease

Question 9

Abiotic factors

Answer 9

-non living factor within an environment
-light, temperature, moisture levels, soil pH, wind intensity, carbon dioxide, oxygen level

Question 10

Biotic factors

Answer 10

-living factors in an environment
-availability of food, predators, pathogens, competition

Question 11

Trophic levels

Answer 11

-feeding relationships between organisms
-all energy is from the sun, transferred to environment as energy lost/ used at each stage
-non-cyclical, at top of food chain, lost to environment not recycled

Question 12

Producers

Answer 12

Produce their own organic nutrients usually using energy from sunlight

Question 13

Primary consumers

Answer 13

Feed on producers - herbivores

Question 14

Secondary consumers

Answer 14

Predators that feed on primary consumers

Question 15

Tertiary consumers

Answer 15

Predators that feed on secondary consumers

Question 16

Quaternary consumers

Answer 16

Predators that feed on tertiary consumers

Question 17

Food chain

Answer 17

Shows the transfer of energy from one organism/ trophic level of the food chain to the next

Question 18

Food web

Answer 18

-A food web is a network of interconnected food chains
-more realistic - animals rarely exist on just one type of food source
-show interdependence

Question 19

Pyramid of numbers

Answer 19

Shows how many organisms are at each level of a food chain.
-width of box = number
-generally, the larger an individual organism, the fewer of them there are

Question 20

Pyramid of biomass

Answer 20

-shows dry mass of organisms at each level
-always pyramid-shaped
-mass of organisms decrease as you go up a food chain

Question 21

Pyramid of energy

Answer 21

-show amount of energy contained in biomass of individuals within different trophic levels
-area = quantity of energy present

Question 22

Losses of energy

Answer 22

Not all energy is transferred from one trophic level to the next
-only 10% of the energy of each trophic level is passed on to the next
-total amount of energy available eventually becomes too small to support another trophic level

Question 23

Losses of energy due to

Answer 23

-don’t eat every part of animal
-not all ingested material is digested, absorbed
-energy is used for movement, generate heat, metabolic processes
-lost as waste - carbon dioxide, water, urea

Question 24

The carbon cycle

Answer 24

-carbon taken out of the atmosphere in the form of carbon dioxide by plants used for photosynthesis
-passed on to animals and microorganisms by feeding
-returned to the atmosphere due to respiration
-when animals/ plants die, don’t decompose fully, carbon in their bodies can be converted over millions of years and pressure into fossil fuels
-fossil fuels are burned (combustion) - carbon combines with oxygen - CO2 released into the atmosphere

Question 25

How nitrogen is taken out of the air/ converted into something easier to absorb

Answer 25

-nitrogen fixing bacteria in soil/ roots take nitrogen gas and change it into nitrates in the soil
-lightning can ‘fix’ nitrogen gas, split bonds between two atoms, turn them into nitrous oxides that dissolve in rainwater and leach into the soil

Question 26

Nitrogen cycle

Answer 26

-Plants absorb nitrates in soil, use to make proteins
-Animals eat plants
-Waste from animals sends nitrogen back to soil as ammonium compounds
-Nitrifying bacteria convert ammonium compounds –> nitrites –> nitrates (nitrification) –> absorbed by plants
-denitrifying bacteria (found in poorly aerated soil) take nitrates out of soil, convert to nitrogen gas

Question 27

Sulphur dioxide - pollution

Answer 27

-combustion of fossil fuels that contain sulphur impurities - creates sulphur dioxide and nitrogen oxides
-gases react with oxygen and dissolve in rainwater
-produce dilute sulphuric acid/ nitric acid
-acid rain

Question 28

Acid rain

Answer 28

-can damage plants
-make rivers, lakes, too acidic
-results in the death of certain aquatic organisms
-cause the leaching of minerals that are toxic to fish, such as aluminium into lakes

Question 29

Greenhouse gases

Answer 29

-gas that absorbs infrared radiation from the sun so it remains trapped in the Earth’s atmosphere
-water vapour
-carbon dioxide
-methane
-nitrous oxides
-CFCs

Question 30

Carbon dioxide - pollution

Answer 30

-produced during the combustion of fossil fuels
-deforestation - trees cannot absorb CO2 from atmosphere

Question 31

Methane - source

Answer 31

-from the decomposition of waste by microorganisms
-fermentation by microorganisms in the stomach of cattle
-fermentation by bacteria in rice fields

Question 32

Greenhouse effect

Answer 32

-The Sun emits rays that enter the Earth’s atmosphere
-The heat bounces back from the Earth’s surface
-Some heat is reflected back out into space
-Some heat is absorbed by greenhouse gases and is trapped within the Earth’s atmosphere – this is normal

Question 33

Consequences of enhanced greenhouse effect

Answer 33

-ocean temperatures increase - melting of ice caps
-increasing temperatures - cause extreme weather like superstorms, flooding, droughts
-change ecosystems

Question 34

Effect of toxic chemicals (pesticides/ herbicides) - water pollution

Answer 34

-runoff into rivers
-chemicals cannot be broken down by organisms
-can be absorbed by aquatic plants/ invertebrates and build up in tissues of organisms over time - bioaccumulation
-at each stage of the food chain, level of chemicals increase
-eventually build up to toxic levels in predators - lead to death/ failure to breed - biomagnification

Question 35

Untreated sewage - water pollution

Answer 35

-sewage provides a good source of food for bacteria which increase rapidly
-depletes oxygen dissolved in the water as they respire aerobically
-lack of oxygen results in the death of aqautic organisms such as fish
-eutrophication

Question 36

Fertilisers - water pollution

Answer 36

-cause increased growth of algae, water plants
-results in algal bloom
-blocks sunlight so water plants on the bottom start to die
-algae also dies when competition for nutrients become too intense
-dead plants/ algae are a good source of food
-lead to eutrophication
-death of aquatic organisms

Question 37

Effects of deforestation

Answer 37

-loss of biodiversity
-soil erosion
-flooding
-increased CO2 in the atmosphere
-disturbance of evapotranspiration

Question 38

Deforestation - loss of biodiversity

Answer 38

-as rainforest habitat is destroyed
-causes the loss of large numbers of plants/ animals

Question 39

Deforestation - soil erosion

Answer 39

-tree roots help stabilise the soil, prevents it from being eroded by the rain
-trees take up nutrients/ minerals from the soil through their roots
-without trees, nutrients and minerals will remain unused in the soil
-washed away into rivers and lakes by rain (leaching)
-loss of nutrients is permanent, makes it difficult for forest trees to regrow, even if land is not cultivated with crop plants/ grass for cattle

Question 40

Deforestation - increased CO2 in the atmosphere

Answer 40

-trees carry out photosynthesis where they take in carbon dioxide, release oxygen
-removal of trees, less carbon dioxide is removed from the atmosphere, less oxygen released
-trees are often burned to clear for land, releases carbon dioxide

Question 41

Deforestation - disturbance of the water cycle

Answer 41

-water released by trees by transpiration leads to the formation of clouds
-results in rainfall nearby
-if trees are cut down, local area may become drier due to less rainfall