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Biology IGCSE > Topic 20 > Flashcards

Topic 20 Flashcards

1
Q

Increased food production by humans: agricultural machinery

A

Machinery is quicker and more efficient than manual labour -> crops can be grownnand harvested over larger areas of land

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2
Q

Increased food production by humans: chemical fertilisers

A

They replace missing ions in the soil or provide more of them -> helps to improve crop yeilds by boosting plant growth

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3
Q

Increased food production by humans: Insecticles

A

These are chemicals that are sprayed onto crops amd they kill insects without killing the actual ceop -> fewer plants are damaged or destroyed by insects which increases crop quality and yield

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4
Q

Increased food production by humans: herbicides

A

These are chemicals that can be sprayed around crops to kill weeds meaning plants face less competitionsp from weeds for nutrients, water and light -> increases the quality and yield of crop plants

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5
Q

Increased food production by humans: selective breeding

A

Used to improve production by crop plants and livestock

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6
Q

Monoculture

A

Single crop species grown at one time on a large area of land

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7
Q

Monoculture: advantages

A

. More efficient as plants are planted/harvested using the same chemicals -> easier to manage and more cost-effective
. Higher yields mean more food is produced -> greater profits for farmers
. Food produced is cheaper for consumers

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8
Q

Monoculture: disadvantages

A

. Low genetic variation -> if a disease breaks out it could kill all the crop grown
. Lots of pesticided used pollute the fresh water/environment -> kill beneficial insects and build up in food chains
. Reduced biodiversity -> then contain fewer species than a natural ecosystem

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9
Q

Intensive livestock production

A

Limits the movement of animals and keeps them in a temperature-controlled environment

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10
Q

Intensive livestock production: advantages

A

. More meat produced -> more energy is available for growth as animals use less energy for moving
. Easier for farmers to monitor and protect animals from predators
. Greater profit and cheaper food

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11
Q

Intensive livestock production: disadvantages

A

. Waste can build up so diseases can soread easily or pollite water sources
. Chemicals used to treat diseases can pollute the environment
. Ethical objection -> people think it’s unnatural, uncomfortable and cruel

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12
Q

Biodiversity

A

Number of different species that live in an area

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13
Q

Destruction of habitats by human activities

A

Human activities can have a negative impact on habitats by affecting food webs and chains
. Increased area for housing, crop plant production and livestock production
. Extraction of natural resources
. Freshwater and marine pollution

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14
Q

Deforestation -> effect: loss of biodiversity

A

When habitats are destroyed species that live in them will die or move away reducing biodiversity in the area

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15
Q

Deforestation -> effect: extinction

A

Danger that some species can die out completely if they can’t find or are unable to move to other suitable habitats

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16
Q

Deforestation -> effect: loss of soil

A

When trees are removed there aren’t roots to stabilise the soil during heavy rain and so soil is easily washed away and nutrients are lost -> makes it harder for new trees to grow later

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17
Q

Deforestation -> effect: flooding

A

Without trees flooding is more likely which can destroy habitats and kill wildlife

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18
Q

Deforestation -> effect: increase of carbon dioxide in atmosphere

A

Removing trees reduces the amount of photosynthesis taking place SO less caebon dioxide is removed from the atmosphere -> increased concentrations of CO2 contributes to global warming

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19
Q

Water pollution -> Sewage and fertilisers

A

Untreated sewage and excess fertilisers causes nitrates and other ions to end up in rivers and lakes causing eutrophication -> serious damage to river and lake ecosystems and eventually the death of aquatic organisms

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20
Q

Water pollution: eutrophication of water

A
  1. Increased availability of nitrates and other ions
  2. Increased growth of producers
  3. Increased decomposition after death of producers
  4. Increased aerobic respiration by decomposers
  5. Reduction in dissolved oxygen
  6. Death of organisms requiring dissolved oxygen in water
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21
Q

Air pollution: production of carbon dioxide -> burning fossil fuels and deforestation

A

. Burning fossil fuels: releases lots of carbon dioxide
. Deforestation:
- CO2 isn’t removed by plants through photosynthesis
- CO2 released when trees are burnt or when dead wood is left to decompose

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22
Q

Air pollution: production of methane -> naturally and artificially

A

. Naturally: theough various sources like rotting plants in marshland
. Artficially: through ‘man-made’ sources like growing rice and raising cattle

23
Q

Air pollution: greenhouse effect and climate change

A

. Greenhouse effect: greenhouse gasses in the atmosphere absorb most of the heat that woukd normally be radiated out into space and re-radiate it in all direction (including back towards the earth) -> these greenhouse gases include carbon dioxide and methane
. Increasing levels of greenhouse gasses enhances the greenhouse effect whicb causes the earth to heat up -> this is globak warming which is a type of climate change

24
Q

Non-biodegradable plastics

A

Can’t be broken down through biological decomposition (by organsims)

25
Non-biodegradable plastics affect aquatic ecosystems: food chain contamination
Aquatic life mistakes plastci for food which causes intestinal blockages or poisoning from chemicals that slowly leak the plastics -> plastic enters food chain
26
Non-biodegradable plastics affect aquatic ecosystems: entrapment of organisms
Large quantities of plastic and other kinds of rubbish build up inbthe ocean forming an 'island' -> organisms can get entangles, trapped or strangled by plastic islands or even just by individual plastic items
27
Non-biodegradable plastics affect terrestrial ecosystems: food chain contamination
Plastics can give out poisonous toxins and chemicals that cause land pollution -> in the food chain this kills organisms
28
Non-biodegradable plastics affect terrestrial ecosystems: air pollution
When plastics are burnt toxic gasses can be released into the atmosphere
29
Non-biodegradable plastics affect terrestrial ecosystems: landfill
Plastic in landfills take a lomg time to decompose, landfills look unsightly and buried waste releases toxins into surrounding soil making it unsuitable for crops or grazing animals
30
Sustainable resources
Doesn't run out because it's made as rapdily as it's removed from the environment
31
Examples of sustainable resources: fish stocks
Particular populations of fish in the sea
32
Examples of sustainable resources -> conserving fish stock: legal quotas
Limits to number and size of fish that can be caught in certain areas -> helps to prevent certain species from being overfished
33
Examples of sustainable resources -> conserving fish stock: closed seasons
There's rules about the time of year you can catch fish in certain areas -> bans fishing during breeding season allowing fish stocks to replenish
34
Examples of sustainable resources -> conserving fish stock: protected areas
Certain types of fishing are restricted or banned there
35
Examples of sustainable resources -> conserving fish stock: controlled net types and mesh sizes
Different limits to mesh size of the fishing net depending on what's being fished -> reduces number of 'unwanted' and discarded fish (ones that are accidentally caught)
36
Examples of sustainable resources -> conserving fish stock: monitoring
Surveys and sampling techniques used to keep and eye on sie of fish stocks, size, age and movement of the fish -> helps to inform other policies
37
Examples of sustainable resources -> conserving fish stock: education
People shopping for fish can make better choices
38
Examples of sustainable resources: forests -> deforestation
Removes trees in area
39
Examples of sustainable resources -> conserving forests: legal quotas
Limits applied to the number of trees can be cut down in forests
40
Examples of sustainable resources -> conserving forests: protected areas
Deforestation is banned by the law
41
Examples of sustainable resources -> conserving forests: education
People will want to protect them for deforestation
42
Endangered species
On that's considered to be at high risk of exctinction
43
Reasons of organisms becoming endangered: climate change
Globar warming causes the earth to heat up -> if organisms can't adapt to changing temperatures or other environmental conditions quickly enough they are at risk of becoming extinct
44
Reasons of organisms becoming endangered: habitat destruction
As species' habitat is destroyed fewer of the organisms can be supported -> as their numbers start to decrease the species can become endangered
45
Reasons of organisms becoming endangered: hunting
If endangered species are hunted they can quickly become extinct -> sometimes endangered animals may also be killed by accident
46
Reasons of organisms becoming endangered: pollution
Affected by pollution -> can cause death
47
Reasons of organisms becoming endangered: introduced species
Introduced species often thrive in their new environment and become invasive -> native species often can't defend themselves againts, or compete with, the invaders
48
Reasons of organisms becoming endangered: overharvesting
If people take so much of an organism that its pollution is unable to reproduce quickly enough to keep up the population size falls
49
Ways of conserving endagnered species: monitoring and protecting species and habitats
Monitoring species' numbers help scientists to identify the species that are most under threat -> protected areas are set up to protect these organismsnand habitats that area under threat
50
Ways of conserving endagnered species: education
Helps people to understand the inposrtance of conservation and what they can do to help
51
Ways of conserving endagnered species: seed banks
Seeds of endangered plant species can be kept in a seed bank -> place with necessary conditions to keep seed alive for a long time (protects and saves plant genetic diversity)
52
Reasons for conservation programmes
. For mantaining or increasing biodiversity . Reducing extinction . Protecting vulnerable ecosystems . Mantaining ecosystem functions -> nutrient cycling and resource provision (food, drugs, fuel and genes)
53
Ways of conserving endagnered species: captive breeding programmes
Animals are bred in captivity -> this is because it's easier for animals to increase their numbers in captivity as there's less infant mortality (death), so more offspring survive to reproduce . Some of these individuals may then be released into the wild to boost or re-establish a population -> this can help make sure the species survives if it dies out in the wild
54
Ways of conserving endagnered species: captive breeding programmes -> AI and IVF
Captive breeding programmes can involve artificial insemination (AI) or in vitro fertilisation (VF) . Al: Involves artificially inserting sperm collected from the male into the females's cervix tomallow fertilisation to take place -> helps individuals who are unable to breed together naturally to reproduce and it increases genetic variation . IVF: an egg is fertilised using sperm in the laboratory and the resulting embryo is then implanted into the female -> helps individuals to reproduce when they are unable to breed together naturally

Biology IGCSE (21 decks)

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