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Biology (N.A.) > UNIT 19 & 20 Organisms and their environment & Human influences on ecosystems > Flashcards

UNIT 19 & 20 Organisms and their environment & Human influences on ecosystems Flashcards

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1
Q

role of sun

A

principal source of energy input to biological systems/of all energy on earth​

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2
Q

flow of energy through living
organisms, including light energy from the
Sun and chemical energy in organisms, and its eventual transfer to the environment

A
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3
Q

sustainable resource

A

📌 a resource that is produced as rapidly as it is removed from the environment so that it does not run out.

[some resources can be conserved and managed sustainably - forests, fish stocks]

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4
Q

population

A

a group of organisms of one species, living in the same area, at the same time

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5
Q

community

A

all the populations of different species in an ecosystem

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6
Q

ecosystem

A

a unit containing the community of organisms and their environment, interacting together

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7
Q

food chain

A

showing the transfer of energy from one organism to the next, beginning with a producer

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8
Q

interpreting food chains

A

​the arrow always starts at the nutrient source and ends at the predator​

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9
Q

food web

A

a network of interconnected food chains

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10
Q

interpret food webs

[which show a large range of organisms within an ecosystem and all of the possible ways the energy could be transferred​]

A
  • break food webs down in to trophic levels [the position of an organism in a food chain, food web or ecological pyramid]
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11
Q

producer

A

an organism that makes its own organic nutrients, usually using energy from sunlight, through photosynthesis

(e.g. plants, algae, phytoplankton)​

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12
Q

consumer

may be…

A

an organism that gets its energy by feeding on other organisms

  • consumers may be classed as primary,
    secondary, tertiary and quaternary according to their position in a food chain
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13
Q

herbivore
carnivore
decomposer

START WITH “an animal that gets its energy…”

A
  • an animal that gets its energy by eating plants
  • an animal that gets its energy by eating other animals
  • an organism that gets its energy from dead or waste organic material
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14
Q

trophic level

A

the position of an organism in a food chain, food web or ecological pyramid

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15
Q

Food pyramids of number​ [sometimes pyramid]

-not varying sizes
- not lifespan

A
  • tell us the population numbers of different trophic levels. usually, larger organisms tend to have smaller populations​

📌 tell us the least amount of information and are the poorest method of ordering the trophic levels.

  • do not account for the varying sizes of the organisms. Larger organisms will require more energy and store more energy in their biomass.
  • does not account for their lifespan. Some organisms live longer than others so will need more energy.​
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16
Q

Food pyramids of biomass​

  • yes difference in size
A
  • measure the differences in the total proportion of mass between different trophic levels. ALWAYS pyramid shaped, bc there must always be more biomass in the previous trophic level to support the next

📌 more accurate bc they account for differences in the size of the organism. ​

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17
Q

Food pyramids of energy​

  • yes size and lifespan
  • diff type of biomass = diff energy requirements
A

Only about 10% of energy is passed from one trophic level to the next as biomass​ [stored in the organism as biomass​]

Only the energy that is used to make new cells is passed on to the next trophic level​

the remaining 90% is lost through waste/excretion, egestion, respiration [as heat], maintaining body heat etc. ​

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18
Q

food pyramids of energy best bc…

A

account for differences in size and lifespan of the organism so are more accurate.

  • also account for the fact that different types of biomass have different energy requirements.​
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19
Q

Explain, in terms of energy loss, why food chains usually have fewer than five trophic levels

A
  • only 10% flow of energy from one trophic level to the next higher level.
  • Not enough energy remaining to support another trophic level
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20
Q

carbon cycle

A
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21
Q

nitrogen cycle

  1. nitrogen fixing bacteria
A

-can fix nitrogen gas into other nitrogenous compounds (e.g. ammonia)

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22
Q
  1. lightning
A

nitrogen gas can also be fixed to ammonia by lightning

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23
Q
  1. nitrification
A

-ammonia toxic to plants, so nitrifying bacteria convert ammonia to nitrites then nitrates in nitrification process

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24
Q
  1. assimilated
A
  1. nitrates can be assimilated by plants to be used in proteins
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25
Q
  1. feeding
A

proteins can be passed from plant to animals by feeding

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26
Q
  1. decomposition, deamination
A

animal and planets eventually die, causing decomposers like fungi and bacteria to perform deamination on proteins, forming ammonia

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27
Q
  1. denitrification
A

nitrogen-containing compounds like nitrates broken back down to nitrogen gas by denitrifying bacteria

28
Q

animal dies, nitrogen compounds in bodies available for plants.

Outline processes that occur to make nitrogen compounds in bodies of dead animals available for plants to absorb [5]

A

eaten by hyenas or vultures
egestion, faeces
decomposition by bacteria and fungi
ammonia to nitrite
nitrite to nitrate
nitrification
plants absorb nitrate

29
Q

factors affecting population growth [4]

A

food supply
predation
disease
competition

30
Q

4 phases

populations have to growth

A

lag
exponential / LOG
stationary
death

31
Q

lag phase

LF = limiting factor

A

food is abundant
population size small
limiting maximum rate of population growth
BIRTH > DEATH

LF: number of reproducing individuals

32
Q

exponential phase

A

food is abundant
deaths low
population large enough to exponentially grow. BIRTH > DEATH
- no LF

33
Q

stationary phase

A

food supply equal to population
📌 birth rate equals death rate 📌
population stays same size

LF: food supply

34
Q

death phase

A

food supply less than population
population size decreases

DEATH RATE > BIRTH RATE

LF: food supply

35
Q

Suggest why population of aphids did not increase rapidly until day 40

A

-small population to start with
-takes time for eggs to hatch
-not enough food
-aphids not sexually mature
-too cold
-predators
-disease
-competition

36
Q

describe how humans have increased food production [5]

  1. agricultural machinery
A
  1. agricultural machinery (tractors, harvesters)

to use larger areas of land and improve efficiency

37
Q
  1. chemical fertilisers
A

to improve yields

38
Q
  1. insecticides
A

to improve quality and yield

39
Q
  1. herbicides
A

to reduce competition with weeds

40
Q
  1. selective breeding
A

to improve production by crop plants and livestock

41
Q

monocultures - ADV

A
  • more efficient (only need to buy equipment/consumables for one crop type, can harvest/tend to all crops at the same time)

-crops can be optimised for highest quality/yields

42
Q

DISADV monocultures

A

-pathogens/disease will affect entire crop

  • destroys soil nutrients (different plants use different proportions of nutrients)
  • has larger impact on local ecosystem; reduces biodiversity

-can lead to soil erosion due to lack of established roots through soil

43
Q

intensive livestock farming

A
  • involves using limited space to farm large quantities of livestock, much higher than what the land could support naturally
  • fed high-calorie feeds. + in some countries, given antibiotics to stop them getting sick, further increasing yields.
  • housed in barns/coops, artificially heated during winter.
44
Q

intensive livestock farming - ADV

A
  • requires less land
    -food can be produced year-round
    -less labor costs
    -less cost of production
45
Q

DISADV [of ILF]

A

-higher risk of disease outbreaks
-herbicides and pesticides used
-can cause eutrophication of water supplies & disrupt ecosystems.
-reduces biodiversity in environment

46
Q

the process of eutrophication of water [6]

  1. ions
A
  1. increased availability of nitrate and other ions
47
Q
  1. producers
A
  1. increased growth of producers

[preventing sunlight from reaching aquatic plants; water oxygen levels fall]

48
Q
  1. decomposition
A
  1. increased decomposition after death of producers
49
Q
  1. respiration
A
  1. increased aerobic respiration by decomposers
50
Q
  1. oxygen
A
  1. reduction in dissolved oxygen
51
Q
  1. organisms
A
  1. death of organisms requiring dissolved oxygen in water
52
Q

risk of untreated sewage

to marine ecosystems

A

-untreated sewage & fertilisers RUN OFF into marine ecosystem has a NEG. IMPACT on MARINE HEALTH

-& can lead to eutrophication of water
-eventually creating an oxygen-deprived environment where very little can survive

53
Q

plastics (non-biodegradable),

in marine habitats: [3]

A

📌 animals can eat plastics & become caught in it

📌 plastics can release toxins into water

📌 small microplastics ingested by marine organisms & enter food chain.

54
Q

plastics - in land habitats: [2]

A

-plastics buried in landfills

-toxins in plastic leech into soil, making it unfit for growing crops or livestock

55
Q

air pollution - greenhouse gases [2 gases, 2 effects]

A

-elevated levels of CO2 and methane in atmosphere

-higher levels => global warming & climate change

56
Q

sources of CO2 and methane [fossil fuels, livestock, melting permafrost]

A

📌 burning fossil fuels increases CO2
📌 keeping livestock generates methane gas
📌 global warming melts permafrost in sub-polar regions => more trapped methane released into atmosphere

57
Q

desc problems caused by non-biodegradable plastics in envir. [3]

A

-does not break down
-fills up landfill sites
-suffocates animals, kills animals trapped in it
-releases toxins

58
Q

why organisms become endangered/extinct [6]

A

-climate change
-habitat destruction
-hunting
-overharvesting
-pollution
-introduced species

59
Q

how endangered species can be conserved [4]

A

-monitoring and protecting species & habitats
-education
-captive breeding programmes
-seed banks

60
Q

how forests can be conserved [4]

A

📌 education [abt sustainable forestry practices]
📌 protected areas
📌 quotas
📌 replanting trees [replacing those harvested]

61
Q

how fish stocks can be conserved [6]

A

📌 education [abt sustainable fishing practices]
📌 closed seasons
📌 protected areas (marine reserves)
📌 controlled net types & mesh size
📌 quotas
📌 monitoring fish stocks

62
Q

reasons for conservation programmes [4]

A

📌 maintaining or increasing biodiversity in ecosystems
📌 reducing extinction
📌 protecting vulnerable ecosystems
📌 maintaining ecosystem functions [nutrient cycling, resource provision (food, drugs, fuel & genes]

63
Q

How eutrophication could’ve resulted in reduction in numbers of cichlid fish [4]

A

Algae grow
Less light for plants for photosynthesis
Therefore plants die
Plants stop producing oxygen
Decomposers feed on dead plants
Use up oxygen in aerobic respiration
Low levels of oxygen cause fish to die
Bacteria produce toxins which cause fish to die

64
Q

effects of large scale deforestation:
1. number of species
2. soils
3. rivers
4. atmosphere

[8]

A
  1. loss of habitat. species decrease/extinction. less food available.
  2. increase in water content, soil erosion, loss of nutrients
  3. soil washed into rivers, rivers flood
  4. atmosphere: more carbon dioxide, less oxygen, co2 not absorbed in photosynthesis, global warming
65
Q

AI (artificial insemination)

A

sperm removed from male placed in female’s uterus with small catheter after it’s washed & processed

66
Q

in-vitro fertilisation (IVF)

A

eggs removed from a woman’s ovaries, eggs are fertilised with sperm (taken from male) in lab, sperm and egg nuclei fuse in vitro, embryo later implanted into woman’s uterus

67
Q

Describe the advantages of drawing a food web rather than a food chain for an
ecosystem. [2]

A

shows complex feeding relationships. all organisms in the ecosystem.

[each species has more than one food source. each species has more than one predator.]

Biology (N.A.) (21 decks)

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