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Biology > Topic 7 - Ecology and Material Cycles > Flashcards

Topic 7 - Ecology and Material Cycles Flashcards

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1
Q

population

A

total number of organisms of one species living in habitat

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2
Q

community

A

total number of organisms of all species living in a habitat

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3
Q

ecosystem

A

a community of organisms along with abiotic parts of their environment

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4
Q

what is interdependence?

A

when species in an ecosystem depend on each other for resources
- a change in population of one species can have a big effect on another species

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5
Q

mutualism

A

a relationship between two organisms from which both benefit

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6
Q

parasitism

A

a relationship between two organisms from which the parasite takes what it needs but host doesn’t benefit

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7
Q

abiotic factor

A
  • a non living factor that affects the population of species and therefore the ecosystem
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8
Q

biotic factor

A
  • a living factor that affects the population of species and therefore the ecosystem
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9
Q

4 examples of abiotic factors

A
  • temp
  • light intensity
  • amount of water
  • level of pollution
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10
Q

competition

A

when organisms within a community are in competition for limited resources so they can reproduce and survive

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11
Q

predation

A

as the population of prey increase the population of predators increase
as population of predators increase the population of prey will decrease

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12
Q

what is meant by the distribution of organisms?

A

where in the ecosystem that organism is mostly found ( which habitat )

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13
Q

2 main ways to study distribution of organisms

A
  • quadrats ( random block sampling )
  • transects
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14
Q

what are quadrats?

A
  • a square frame enclosing a known area
  • divided into smaller sub-squares making it easier to count organisms
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15
Q

Method 1 : Quadrats

A
  • divide area into grid and use RNG to pick random co-ordinates
  • place a quadrat down on that co-ordinate within first sample space
  • count abundance of species within the quadrat
  • repeat steps 1- 3 for that sample space and record mean for the s.s
  • repeat above steps for other sample spaces
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16
Q

when do you use transects?

A

when abiotic factors change gradually across a habitat which is an environmental gradient

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17
Q

Method 2 : Transects

A
  • mark out a line ( environmental gradient ) in the sample space using a tape measure
  • place quadrats along the line and count abundances of organism as you go along
  • record other relevant abiotic factors
  • repeat above steps placing quadrats next to each other in a line
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18
Q

energy transfer in food chains

A

energy is transferred through food chains when organisms eat the biomass of other organisms.

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19
Q

how is energy lost from food chains?

A
  • at each trophic level, animals need to respire to transfer energy to life processes
  • energy transferred to surroundings by heat
  • undigested material lost in faeces
  • not all of the organism is eaten like bones
20
Q

why are shorter food chains better?

A
  • more efficient for top consumers
  • less energy is lost/wasted at each trophic level
  • fewer t.l better
21
Q

what is biodiversity? Why is it so important?

A
  • variety of living organisms in an ecosystem
  • ecosystems with a higher biodiversity can adapt to changes more easily
  • biodiverse ecosystems have fewer species that rely on just 1 organism
22
Q

3 ways humans reduce biodiversity

A
  • eutrophication
  • fish farming
  • introduction of non indigenous species
23
Q

explain why the sun is needed at the start of all food chains?

A
  • it provides energy needed for producers / green plants
  • (which are at the start of the food chain), to photosynthesise
  • the plant produces biomass
  • which is passed on through the food chain by animals eating each other
24
Q

eutrophication (part 1: algal blooms )

A
  • farmers put fertilisers which are rich in nitrates on their fields
  • heavy rain can wash excess nitrate ions into rivers. this process is called leaching and causes eutrophication
  • excess nitrates encourage algae to reproduce rapidly
  • forms algal blooms which prevent light from reaching underwater plants
25
Q

eutrophication (part 2: effects )

A
  • without light, the underwater plants cannot photosynthesise and die and decompose
  • microorganisms that feed on decomposing plants increase in no. and use up O2 in water
  • organisms that need O2 for respiration ( e.g: fish) die
26
Q

fish farming

A

breeding fish in holding nets in open water

27
Q

how does fish farming decrease biodiversity?

A
  • waste produced by fish can leak into open water causing eutrophication and death of wild species
  • parasites spread quickly amongst the high population of fish and infect wild life
  • predators are attracted to nets, trapped in them and die
28
Q

introduction of non indigenous species

A
  • non indigenous species compete with indigenous species for resources
  • sometimes they are better and out-compete the indigenous species
  • the indigenous species decrease in number and die out which reduces biodiversity
29
Q

how can humans maintain biodiversity?

A
  • reforestation
  • conservation schemes
30
Q

4 advantages of maintaining biodiversity

A
  • protecting human food supply
  • minimal damage to food chains
  • providing future medicines
  • ecotourism
31
Q

what is food security?

A
  • having sufficient nutritious and safe food to eat for everybody
32
Q

4 factors that affect food security?

A
  • increasing meat consumption/animal farming
  • environmental change
  • lack of sustainability
  • new pests/pathogens
33
Q

increasing meat consumption and animal farming

A
  • people becoming wealthier so diets likely to change including more meat demand
  • less energy + biomass every time you move up a stage in food chain
  • for given m2 you cam produce lot more food by crowing crops rather than grazing animals
  • risk of over-fishing wild fish so there won’t be enough in future
34
Q

environmental changes caused by human activity

A
  • burning fossil fuels releases CO2 which is greenhouse gas
  • increasing levels of g.g causes global temp to rise causing global warming
  • other human activity such as soil pollution
  • may affect our ability to grow crops
35
Q

new pests and pathogens

A
  • pests and pathogens can cause damage to crops and livestock
  • this reduces the yield and amount that can be sold as food
36
Q

indicator species

A
  • biological indicators that can tell us the effect of human activities on environment
  • organisms very sensitive to their environment
37
Q

indicator species used to assess water pollution

A
  • some invertebrate species are very sensitive to concentration of oxygen in water
  • stonefly larvae and freshwater shrimps indicators of clean water > O2
    -bloodworms and sludge worms adapted to living in polluted environment so indicators of polluted water
38
Q

indicator species used to assess air pollution

A
  • can analyse type of lichen growing in environment
  • sensitive to levels of sulphur dioxide in atmosphere
39
Q

pros of indicator species

A
  • simple and cost effective way of saying if area is polluted
40
Q

cons of indicator species

A
  • can’t give accurate figures for HOW polluted
  • may be other factors other than pollution that affect their population
41
Q

what three factors affect rate of decomposition

A
  • temperature
  • water availability
  • oxygen
42
Q

temperature

A
  • warmer temp increases decomposition rate
  • increase rate of microbial enzymes involved
  • if it’s too hot decomposition slows down or stops because enzymes denatured
43
Q

water availability

A
  • decay takes place faster in moist environments ( > water availability )
  • decomposers need water to survive and carry out biological processes
44
Q

oxygen availability

A
  • decay takes place faster when oxygen supply is plentiful
  • micro-organisms need oxygen to respire aerobically
45
Q

compost

A

decomposed organic matter that is used as natural fertilizer
- recycles nutrients back into soil

46
Q

food preservation methods

A
  • airtight cans
  • storing food in fridge or freezer
  • drying food
  • vacuum packing
47
Q
A

Biology (9 decks)

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