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Biology - IGCSE > Ch 20 - (Human influence on ecosystem) > Flashcards

Ch 20 - (Human influence on ecosystem) Flashcards

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1
Q

What does making food production more intensive mean?

A

producing food more efficiently with a finite amount of land and other resources

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2
Q

What are the ways in which modern technology has increased food supply substantially?

A
  1. Agricultural machinery - replaced humans, improved efficiency due to the ability to farm much larger areas of land
  2. Chemical fertilizers improve yields - fertilizers increase the amount of nutrients in the soil for plants
  3. Insecticides and herbicides - these chemicals kill off unwanted insects and weed species, reducing competition from other plant species (herbicides)
  4. Selective breeding - animals and crop plants which produce a large yield are selectively bred to produce breeds that reliably produce high yields
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3
Q

What happens to the stock in developing countries?

A

Large numbers of livestock are often kept in an area that would not normally be able to support more than a very small number

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4
Q

What food is fed in highly developed countries?

A
  • high energy foods
  • antibiotics
  • artificially warm temperatures
  • do not allow for much movement
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5
Q

What are the advantages of intensive livestock farming?

A
  • Less land is required to produce large amounts of food
  • Food can be produced all year round in controlled environments
  • The cost of production is lower
    therefore food can be sold at cheaper prices
  • There is a lower requirement for labor to produce the food
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6
Q

What are the disadvantages of intensive livestock farming?

A
  • Ethical issues associated with cruel treatment of animals
  • Natural habitats may be destroyed
  • reduction in biodiversity
  • soil erosion
  • large numbers of cattle produce large amounts of methane,
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7
Q

What do intensive farming tend to sue?

A
  • herbicides which may result in eutrophication
  • pesticides which can cause negative effects on the food chain
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8
Q

What is monoculture farming?

A

on a given area of agricultural land only one type of crop is grown

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9
Q

What happens on large scale growth of single variety of plant in monoculture?

A
  • does not happen naturally
  • usually many different species of plants
  • support many species of animals
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10
Q

What are the issues in monoculture?

A
  • biodiversity is much lower
  • increase in pest populations
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11
Q

What does spraying insecticides onto crops lead to?

A
  • harmless insects being killed as well
  • pollution by pesticides (which are often persistent chemicals which accumulate in food chains)
  • in many instances where they are used repeatedly for specific pests, the pests may eventually become resistant to them, reducing their effectiveness
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12
Q

Define biodiversity.

A

number of different species that live in a particular area

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13
Q

What has human activities caused?

A
  • force biodiversity downwards,
  • habitat destruction
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14
Q

What are the reasons for habitat destruction?

A
  • The increasing human population
  • Many habitats are destroyed by humans to make space for other economic activities
  • This interrupts food chains and webs
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15
Q

What is deforestation?

A

clearing of trees (usually on a large scale)

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16
Q

How are trees being replaced?

A
  • by replanting it can be a sustainable practise
  • and to be used in a different way
  • particularly severe example of habitat destruction
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17
Q

What are undesirable effects of deforestation ?

A
  • Extinction of species
  • Loss of soil
  • Flooding
  • Increase of carbon dioxide in the atmosphere
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18
Q

What have human activities lead to?

A
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19
Q

What are the pollutants?

A
  1. Untreated sewage
  2. Chemical waste
  3. Discarded rubbish
  4. Fertilizers
  5. Insecticides & Herbicides
  6. Nuclear fallout
  7. Fallout
  8. Methane
  9. Carbon dioxide
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20
Q

What is source / cause of untreated sewage?

A

Lack of sewage treatment

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21
Q

What is source / cause of chemical waste?

A

mercury chemicals are released from factories

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22
Q

What is source / cause of discarded rubbish?

A

rubbish consists of plastics that is discarded or buried in landfills

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23
Q

What is source / cause of fertilizers?

A

runoff from agricultural land if applied in very High concentration

24
Q

What is source / cause of Insecticides and herbicides?

A

sprayed on crops from to prevent damage by insects and growth of weeds

25
Q

What is source / cause of nuclear fallout ?

A

radioactive particles from explosions of nuclear bomb

26
Q

What is source / cause of methane?

A

cattle farming, rice fields, landfills

27
Q

What is source / cause of carbon dioxide?

A
  • produced when fossil fuels are burnt
  • released when trees are burnt
28
Q

What is the effect of untreated sewage?

A
  • gud source of food for bacteria
  • depletes oxygen dissolved in water (respire aerobically)
  • cause death of aquatic species (eutrophication)
29
Q

What is the effect of chemical waste?

A
  • heavy metals are persistent
  • don’t break
  • can build up in food chains
30
Q

What is the effect of discarded rubbish?

A
  • non bio degradable
  • harms the environment
  • animals eat small plastic
31
Q

What is the effect of fertilizers?

A
  • causes algal bloom
  • provides gud source of food which decomposes bacteria

-

32
Q

What is the effect of insecticides and herbicides?

A
  • bioaccumulation
  • loss of biodiversity
  • damage to beneficial insects
33
Q

What is the effect of nuclear fallout?

A
  • increased risk of cancer
34
Q

What is the effect of methane?

A

contributes to enhanced greenhouse effect

35
Q

What is the effect of carbon dioxide?

A

greenhouse base contributing to climate change

36
Q

What are the effects of algal bloom?

A
  • blocks sunlight
  • water plants and algae die in greater numbers; decomposing bacteria increase in number and use up the dissolved oxygen whilst respiring aerobically
  • less oxygen dissolved in water, so aquatic organisms such as fish and insects may be unable to breathe
37
Q

What are the negative impact of plastic on marine habitats?

A
  • Animals often try to eat plastic or become caught in it, leading to injuries and death
  • As the plastic breaks down it can release toxins that affect marine organisms
  • Once it has broken down into very small particles, it is commonly ingested by animals and enters the food chain
38
Q

what are the negative impacts of plastic on land?

A
  • Plastic is generally disposed of by burying in landfills
  • As it breaks down, it releases toxins into the surrounding soil and as such the land is no good for growing crops or grazing animals
39
Q

What gases insulate the earth as a blanket?

A

Methane and carbon dioxide

40
Q

What human activity increases levels of methane and carbon dioxide?

A
  1. Burning fossil fuels increases carbon dioxide
  2. Keeping livestock generates methane gas
  3. Global warming
41
Q

What are sustainable resources?

A

resources from the Earth; some, such as food, water and wood,

42
Q

What is a sustainable resource?

A

produced as rapidly as it is removed from the environment so that it does not run out

43
Q

What resources are non - renewable ate conserved and reused?

A
  • reducing the amount we use and finding other, sustainable resources to replace them
  • energy source
  • raw materials
  • products such as plastic, paper, glad or metal can be reused or recycled
  • forests and fish stalks maintained by harvesting sustainably
44
Q

Define sustainable development.

A

development providing for the needs of an increasing human population without harming the environment

45
Q

How do we balance conflicting demands in sustainable production?

A
  • the need for local people to be able to utilize the resources
  • he needs of large companies to make money from resource
  • the need for balancing the needs of humans for resources
  • the needs of the animals and plants
  • current populations need with what future populations might need -
46
Q

Describe how sustaining forest is important?

A
  • produce paper products and provide wood for timber
  • replant similar trees when mature trees are cut
  • introduction of several schemes designed to monitor logging companies
  • Education
47
Q

What are ways in which we sustain fish stalks?

A
  • Controlling the number of fish
  • Controlling the size of fish caught
  • Controlling the time of year that certain fish can be caught
  • Restocking (breeding and keeping offspring until they are large enough to survive in their natural habitat then releasing)
  • Educating fishermen as to local and international laws and consumers
48
Q

Why are endangered species at risk?

A

the population of the species may fall below a critical level

extinct

49
Q

What are the reasons why species become endangered?

A
  • hunting
  • climate change
  • pollution
  • loss of habitat
  • introduction of non-native specie
50
Q

What are conservation methods use to save endangered species ?

A
  1. education programmes
  2. captive breeding programmes
  3. monitoring and legal protection of the species and of their habitats

4.seed banks as a conservation measure for plants

51
Q

Why may a specie be at risk for becoming extinct?

A
  • if there is not enough genetic variation in the population
  • remaining organisms are all very similar and may not have the adaptations to survive such changes
52
Q

What are some moral, cultural, and scientific reasons for conservation programs?

A
  • reducing extinction rates
  • protecting vulnerable ecosystems (eg the rainforests)
  • protecting our future food supply
  • maintaining nutrient cycles and possible sources of future medical drugs and fuels
53
Q

what are there numerous reasons on why conservation programs are important?

A
  1. Maintaining or increasing biodiversity - allows ecosystems to remain stable
  2. Reducing extinction -
    Helps to retain iconic species and maintain biodiversity
54
Q

What are ways in which ecosystem functions are maintained?

A
  1. Food - making sure we have enough for the population
  2. Drugs - having access to plants for plant-based remedies
  3. Fuel - for important activities such as cooking
  4. Genes - so the gene pool remains wide and variety exists in all species
55
Q

What are conservation techniques used for?

A

maintain biodiversity

56
Q

What are examples of conservation techniques?

A
  1. Artificial insemination (AI): in captive breeding programmes
  • This allows large numbers of offspring to be produced without the need for conventional sexual intercourse between males and females
  1. In vitro fertilisation (IVF) in captive breeding programmes
  • This allows gametes with known alleles to be used in ensuring the next generation remains biodiverse
57
Q

What are the risks to a species?

A
  • population size decreases, a species will experience reduced genetic variation
  • more susceptible to environmental change
  • less resilient and has a greater risk of extinction

Biology - IGCSE (19 decks)

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