4. ecology and the environment

Question 1

define population

Answer 1

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

Question 2

define community

Answer 2

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

Question 3

what is interdependence

Answer 3

within a community, each species depends on others for food, shelter, pollination, seed dispersal etc- if one is removed it can affect the whole community

Question 4

define habitat

Answer 4

the place where an organism lives

Question 5

define ecosystem

Answer 5

all the biotic factors and all the abiotic factors that interact within an area at one time (non and living components)

Question 6

define biodiversity

Answer 6

the range and variety of different species or organisms on earth, or within an ecosystem

Question 7

why is biodiversity important?

Answer 7

• different species depend on each other for food, shelter and maintenance of the physical environment
• high biodiversity ensures the stability of ecosystems by reducing the dependence of one species on another for the reasons above
• populations with high diversity are also more likely to be resilient to sudden environmental impacts or disease

Question 8

what is an abiotic factor?

Answer 8

non living
e.g. temperature, light intensity and wind speed

Question 9

how does light intensity affect a community

Answer 9

light is needed by plants for photosynthesis, more light leads to an increase in the rate of photosynthesis and an increase in plant growth rate

Question 10

how does temperature affect a community

Answer 10

affects the rate of photosynthesis in plants

Question 11

how does moisture levels affect a community

Answer 11

plants and animals require water to survive

Question 12

how does soil pH and mineral content affect a community

Answer 12

different species of plants are adapted to different soil pH levels and nutrient concentration levels

Question 13

how does wind intensity and direction affect a community

Answer 13

wind speed affects transpiration rate in plants, transpiration affects the rate of photosynthesis as it ensures water and mineral ions are transported to the leaves

Question 14

how does carbon dioxide levels affect a community

Answer 14

co2 is required for photosynthesis in plants, so affects the rate of photosynthesis

Question 15

how does oxygen levels affect a community

Answer 15

some aquatic animals (like fish) can only survive in water with high oxygen concentrations

Question 16

what is a biotic factor

Answer 16

living factor
e.g. competition, predation and disease

Question 17

how does availability of food affect a community

Answer 17

more food means organisms have a higher chance of surviving and reproducing, this means their populations can increase

Question 18

how does new predators affect a community

Answer 18

in balanced ecosystems, predators catch enough prey to survive but not so many that they wipe out the prey population, if a new predator is introduced to the ecosystem, it may become unbalanced

Question 19

how does new pathogens affect a community

Answer 19

if a new pathogen enters an ecosystem, the populations living there will have no immunity of resistance to it and the population may decline or be wiped out

Question 20

how does competition affect a community

Answer 20

if 2 species compete for the same resource(s) and one is better adapted to take advantage, then the species will outcompete the other, this may continue until there are too few members of the lesser adapted species to breed successfully

Question 21

what are trophic levels

Answer 21

• term used to describe the feeding relationships between organisms
• is the level occupied by an organism within a food chain or food web

Question 22

what are producers

Answer 22

they produce their own organic nutrients usually using energy from sunlight

Question 23

what are primary consumers

Answer 23

herbivores- they feed on producers (plants)

Question 24

what are secondary consumers

Answer 24

predators that feed on primary consumers

Question 25

what are tertiary consumers

Answer 25

predators that feed on secondary consumers

Question 26

true or false: animals can be at different trophic levels within the same food web as they may both eat primary, secondary and/ or tertiary consumers

Answer 26

true!

Question 27

what are decomposers

Answer 27

bacteria and fungi that get their energy from feeding off dead and decaying organisms and undigested waste (such as faeces) by secreting enzymes to break them down

Question 28

why are food webs are more realistic way of showing connections between organisms within an ecosystem instead of a food chain?

Answer 28

as animals rarely exist on just one type of food source

Question 29

what does a food chain show

Answer 29

the transfer of energy from one organism to the next

Question 30

fill in the blank: a food web shows the _______________ of organisms

Answer 30

interdependence

Question 31

what are most of the changes in populations or animals and plants a result of?

Answer 31

human impact- either by overharvesting of food species or by the introduction or foreign species to a habitat

Question 32

what are pyramids of numbers

Answer 32

- shows the number of organisms at each trophic level - the width of the bars represents the relative number of organisms at that trophic level - the bottom bar will always be a producer - not always pyramid shaped

Question 33

what is a pyramid of energy

Answer 33

- shows the amount of energy at each trophic level - always the shape of a pyramid- as energy is lost at each trophic level (about 10% transferred)

Question 34

what is a pyramid of biomass

Answer 34

- represents the dry mass of organisms at each trophic level - the unit is usually mas per surface area - will always have a pyramid shape as biomass decreases - represents quantity of organisms and interdependence more accurately

Question 35

what is the equation for percentage efficiency transfer

Answer 35

percentage efficiency transfer = biomass in higher trophic level / biomass in lower trophic level x100

Question 36

fill in the blanks: _________ convert light energy into _______ energy- this occurs during ___________, when producers convert co2 and h2o into _______ and oxygen producers use this glucose (during __________) to produce their own _______ (a store of chemical energy)

Answer 36

producers chemical photosynthesis glucose respiration biomass

Question 37

fill in the blanks: when _______ consumers eat producers, they break down the biomass of the producer (________) and use the ______ energy to ______ or sustain their own biomass (same thing occurs when ________ consumers eat primary consumers) in this way chemical energy and _______ is _________ from one trophic level to the next

Answer 37

primary digestion chemical increase secondary biomass transferred

Question 38

approximately what % of energy is transferred at each trophic level

Answer 38

10%

Question 39

how is energy lost at each trophic level

Answer 39

- energy is used for movement - used to generate heat - for metabolic processes - some is lost as waste (carbon dioxide, water, urea) - not all the ingested material is digested and absorbed- some is egested as faeces - some biological material is inedible (like bones and fur)

Question 40

what do nitrogen fixing bacteria do in the nitrogen cycle

Answer 40

convert nitrogen gas and convert it into nitrates in the soil found in soil and in the root nodules of certain plants like peas and beans lightning also does this can be called nitrogen fixation

Question 41

what do nitrifying bacteria do

Answer 41

convert ammonium ions into nitrates, which can then be absorbed by plants can be called nitrification

Question 42

what do denitrifying bacteria do

Answer 42

take nitrates out of the soil and convert them back into nitrogen gas can be called denitrification

Question 43

what is the consequence of sulfur dioxide pollution

Answer 43

combines with water vapour to form acid rain, which damages plants, aquatic life and soil. can also cause respiratory problems in humans

Question 44

what is the consequence of carbon monoxide pollution

Answer 44

binds irreversibly to haemoglobin, which reduces oxygen transport in blood, can lead to suffocation and death in high concentrations

Question 45

name 5 greenhouse gases

Answer 45

water vapour, carbon dioxide, methane, nitrous oxides, CFCs

Question 46

fill in the gaps! human activities have led to increasing levels of ______ _______ and ______ in the atmosphere CO2 is produced during the __________ of fossil fuel methane is produced by _____ as they digest grass, and released by rice paddy fields

Answer 46

carbon dioxide methane combustion cattle

Question 47

describe the greenhouse effect process

Answer 47

- the sun emits rays that enter the earth's atmosphere - 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 the enhanced greenhouse effect happens when increasing levels of greenhouse gases from human activities cause the earths average temperature to rise above normal- leading to global warming

Question 48

when does the enhanced greenhouse effect happen

Answer 48

when increasing levels of greenhouse gases from human activities cause the earths average temperature to rise above normal- leading to global warming

Question 49

what are the consequences of global warming?

Answer 49

- ocean temperatures increasing (causes polar ice caps to melt, rising sea levels- flooding, coral bleaching) - increasing temperatures (causes extreme weather like super storms, flooding, droughts) - changes in or loss of habitats - decreases in biodiversity (as food chains are disrupted and extinction rates increase) - increases in migration of species to new places, including increased spread of pests and disease

Question 50

what is the uptake of carbon by living organisms

Answer 50

- carbon dioxide is taken out of the atmosphere in the form of carbon dioxide by plants during photosynthesis - the carbon is used to make glucose, which can be turned into carbohydrates, fats and proteins within the biomass of plants

Question 51

what is the transfer of carbon between living organisms

Answer 51

- carbon is passed from plants to animals when herbivores feed - carbon passes between animals when carnivores feed

Question 52

what is the release of carbon into the atmosphere

Answer 52

- carbon returns to the atmosphere in the form of carbon dioxide during respiration (respiration occurs in plants and animals, microorganisms such as bacteria and fungi use dead and waste material to fuel respiration releasing CO2 during decomposition) - if animals and plants die in conditions where decomposers are not present the carbon in their bodies can be converted into fossil fuels; these can be burned to release carbon dioxide into the atmosphere by combustion

Question 53

what are the stages of the carbon cycle

Answer 53

respiration, photosynthesis, decomposition and combustion

Question 54

what is eutrophication

Answer 54

the process when minerals from agricultural fertilisers leach into water bodies (such as lakes and streams)

Question 55

what happens after eutrophication (what are the biological consequences of eutrophication)

Answer 55

- fertilisers are high in nitrogen (essential mineral for plant growth) so can result in the overgrowth of aquatic plants and algae at the water surface - aquatic plants below the surface die due to reduced light levels and are broken down by decomposers - decomposers increase, and the increased respiration of them uses up oxygen in the water- reducing dissolved oxygen levels - the water no longer contains enough oxygen so many aquatic organisms die

Question 56

when can water pollution occur

Answer 56

- when sewage is washed into waterways - e.g. when sewers overflow or agricultural waste is washed off fields due to heavy rain - can result in an increase in the number of pathogenic bacteria present

Question 57

what are the effects of sewage pollution

Answer 57

- causes an increase in growth of aerobic bacteria, which feed on biological waste - these reduce the availability of dissolved oxygen in water - aquatic organisms that are sensitive to oxygen levels die, leaving only organisms that can survive at low concentrations of oxygen - therefore the aquatic ecosystems decrease in biodiversity

Question 58

what are the effects of deforestation

Answer 58

- leaching - soil erosion - disturbance of evapotranspiration (water cycle disturbance) - disturbance of the carbon cycle (+ increased global warming/ balance of atmospheric gases)

Question 59

what is leaching as an effect of deforestation

Answer 59

soil minerals are not taken up by trees and are instead washed away by rain into nearby bodies of water

Question 60

what is soil erosion as an effect of deforestation

Answer 60

soil is not held together by tree roots and organic matter, so is more likely to be washed and/ or blown away

Question 61

what is water cycle disturbance as an effect of deforestation

Answer 61

the removal of trees reduces the release of water vapour into the atmosphere by transpiration, reducing cloud formation and rainfall

Question 62

what is carbon cycle disturbance and increased global warming as an effect of deforestation

Answer 62

- the removal of trees reduces photosynthesis, so less carbon dioxide is removed from the atmosphere and stored in plant tissues - combustion of felled trees increases release of carbon dioxide into the atmosphere