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BIOLOGY IGCSE > 20. Human influences on ecosystems > Flashcards

20. Human influences on ecosystems Flashcards

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1
Q

What are 5 ways in which humans have increased food production?

A
  1. agricultural machinery to use larger areas of land and improve efficiency
  2. chemical fertilisers to improve yields
  3. insecticides to improve quality and yield
  4. herbicides to reduce competition with weeds
  5. selective breeding to improve production by crop plants and livestock
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2
Q

How does agricultural machinery increase food production?

A

use larger areas of land and improve efficiency

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3
Q

How do chemical fertilisers increase food production?

A

improve yields

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4
Q

How do insecticides increase food production?

A

improve quality and yield

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5
Q

How do herbicides increase food production?

A

reduce competition with weeds

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6
Q

How does selective breeding increase food production?

A

improve production by crop plants and livestock

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7
Q

What two measures improve yield of, ergo increase, food production?

A

chemical fertilisers and insecticides

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8
Q

What helps to reduce competition with weeds in food production?

A

herbicides

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9
Q

What improves the quality (and yield) of food production?

A

insecticides

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10
Q

What improves production by crop plants and livestock?

A

selective breeding

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11
Q

What helps to use larger areas of land and improve efficiency in food production?

A

agricultural machinery

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12
Q

Describe the advantages of intensive farming.

A
  • improves efficiency
  • improves yield
  • reduces production costs
  • simplicity
  • large land allows use of machinery
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13
Q

Describe the disadvantages of intensive farming.

A
  • land clearance
  • reduced biodiversity
  • soil damage
  • water pollution
  • air pollution
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14
Q

Why does intensive farming improve efficiency and yield?

A

crop or animal grows optimally and it is produced in an efficient way

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15
Q

Why does intensive farming reduce production costs?

A

farmers can work in a focused and efficient manner, increasing profit + decreasing cost of produce

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16
Q

Why is intensive farming simpler?

A
  • monoculture: only one type of crop considered (preparing the soil, choosing fertiliser, irrigating land…)
  • specific herbicides/insecticides can be chosen for that specific plant
  • livestock: needs of only one particular animal are considered, such as particular medicines or food.
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17
Q

Why does intensive farming cause land clearance?

A
  • before planting new crop, farmers must clear the land of other plant species
  • create space for livestock
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18
Q

Why does intensive farming cause air pollution?

A
  • decomposing animal waste releases ammonia
  • waste digestive gas methane (greenhouse gas)
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19
Q

Why does intensive farming soil damage?

A
  • heavy machinery compacts soil, reducing capacity to hold air and water, difficult for plants to grow
  • large, exposed areas of land vulnerable to erosion
  • growing same crop over and over: organic matter + nutrients in soil will be used up, more fertilisers and the soil structure used, damaging soil, making land more vulnerable to erosion
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20
Q

Why does intensive farming cause water pollution?

A

Water runoff from the fields can carry fertilisers, insecticides + herbicides into local water courses, may harm the organisms in water (directly/indirectly)

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21
Q

Why does intensive farming cause reduced biodiversity?

A

insecticides may kill non-pest insects, reducing amount of food available for other animals, damaging the food web

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22
Q

What are 2 methods of intensive farming?

A
  • monoculture
  • intensive livestock production
23
Q

What is monoculture?

A

growing only one variety of crop in an area at a given time

24
Q

What is biodiversity?

A

the number of different species that live in an area

25
Q

What are 3 reasons for habitat destruction?

A
  • increased area for housing, crop plant production + livestock production
  • extraction of natural resources
  • freshwater and marine pollution
26
Q

What is one way humans can negatively impact the environment?

A

through altering food webs and food chains

27
Q

Altering food webs and food chains…

A

means humans can have a negative impact on habitats

28
Q

What are 5 effects of deforestation?

A
  • reducing biodiversity
  • extinction
  • loss of soil
  • flooding
  • increase of carbon dioxide in the atmosphere
29
Q

What is an example of habitat destruction?

A

deforestation

30
Q

Deforestation is an example of what?

A

habitat destruction

31
Q

Describe the effects of untreated sewage on aquatic ecosystems.

A
  • contains bacteria, can be harmful and infect coral in the ocean, leading to their bleaching + death
  • may contain hormones + drugs, which can affect negatively the reproduction of some organisms (eg fish and amphibians)
  • causes algal bloom + eutrophication
  • decomposers respire + use up oxygen in the water, less oxygen available to aquatic organisms (may all die in extreme cases)
  • sometimes contains industrial waste water from factories: can contain toxic heavy metals (eg mercury and arsenic). Can become concentrated in bodies of animals, who may eventually contain so much that it leads to death/inability to breed
32
Q

Describe the effects of fertilisers on aquatic ecosystems.

A
  • fertilisers contain nitrate and phosphate, which help algae + other producers in the water to grow rapidly.
  • algae form a bloom in which green algae cover the surface of the water
  • high levels of green algae on the surface stops sunlight entering , eventually reducing levels of oxygen in the water
  • can lead to many aquatic life dying
33
Q

Describe the effects (6) of non-biodegradable plastics in terrestrial ecosystems.

A
  • plastic breakdown releases greenhouse gases
  • toxins from plastic breakdown leach into soil, polluting land
  • land animals mistakenly eat plastic
  • burning of plastic may lead to toxic chemicals released into air
  • land animals may become entangled in plastic
  • long-term exposure to air, water and light can cause plastics to form toxic compounds
34
Q

Describe the effects (4) of non-biodegradable plastics in marine ecosystems.

A
  • aquatic life may mistakenly eat plastic, blocking digestive system and they starve
  • aquatic life may become entangled in plastic
  • much of consumed seafood contaminated w/ microplastics (ingestion of nurdles)
  • long-term exposure to air, water and light can cause plastics to form toxic compounds
35
Q

Describe the effects of air pollution.

A

enhanced greenhouse effect and climate change

36
Q

What are sources of air pollution?

A

increased emissions of greenhouse gases, such as carbon dioxide and methane

37
Q

What are sources of carbon dioxide?

A

NATURAL:
- volcanoes
- respiration in living organisms
HUMAN:
- burning fossil fuels
- producing electricity
- deforestation

38
Q

What are sources of methane?

A
  • livestock (waste digestive gases)
  • decomposing rubbish
  • rice paddy fields
  • accidental releases of natural gas
39
Q

Explain the process of eutrophication of water.

A
  • additional nitrate and other ions in water
  • increased growth of producers (algae)
  • increased decomposition after death of producers
  • increased aerobic respiration by decomposers
  • reduced oxygen
  • death of organisms in water
40
Q

What is a sustainable resource?

A

a resource which is produced as rapidly as it is removed from the environment, so it does not run out

41
Q

What are two resources that can be conserved and managed sustainably?

A
  • forests
  • fish stocks
42
Q

What do forests and fish stocks have in common?

A

they are both resources that can be conserved and managed sustainably

43
Q

Why do organisms become endangered or extinct (6)?

A
  • climate change
  • habitat destruction
  • hunting
  • overharvesting
  • pollution
  • introduced species
44
Q

What are 4 ways in which endangered species can be conserved?

A
  • monitoring + protecting species and habitats
  • education
  • captive breeding
  • seed banks
45
Q

What are 4 ways forests be conserved?

A
  • education
  • protected areas
  • quotas
  • replanting
46
Q

What are 6 ways fish stocks be conserved?

A
  • education
  • closed seasons
  • protected areas
  • controlled net types + mesh size
  • quotas
  • monitoring
47
Q

State 4 reasons for conservation programmes.

A
  • maintaining or increasing biodiversity
  • reducing extinction
  • protecting vulnerable ecosystems
  • maintaining ecosystem functions
48
Q

What does it mean to maintain ecosystem functions?

A
  • nutrient cycling
  • providing resources (food, drugs, fuel, genes)
49
Q

Nutrient cycling and providing resources are examples of _______.

A

ecosystem functions

50
Q

Explain the risks to a species if its population size and genetic variation decreases.

A

population becomes more vulnerable to diseases and change

51
Q

What happens if a species’ population size decreases?

A

genetic variation is reduced

52
Q

What are two methods used by captive breeding programmes?

A
  • IVF (in vitro fertilisation)
  • AI (artificial insemination)
53
Q

Describe the use of artificial insemination in captive breeding programmes.

A
  • obtain a sperm sample from desired male
  • semen is harvested from the sample and transported to breeding female
  • semen artificially inserted into female’s reproductive tract, hopefully leading to successful pregnancy
54
Q

Describe the use of in vitro fertilisation in captive breeding programmes.

A
  • sperm from male and eggs from the female are extracted
  • fertilisation is carried out under controlled conditions in a Petri dish in the laboratory
  • once egg is fertilised and has started to divide into an embryo, it is inserted into the reproductive tract of a female

BIOLOGY IGCSE (19 decks)

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