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IB Biology > C.3 Impacts of humans on ecosystems > Flashcards

C.3 Impacts of humans on ecosystems Flashcards

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1
Q

What are the two ways to describe species within any ecosystem?

A

Endemic or alien species

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2
Q

What is an endemic species?

A

Those which are native to a defined geographic region

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3
Q

What are alien species?

A

Those that have been transferred from their natural habitat to a new environment

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4
Q

When is a species classed as invasive?

A

If an introduced alien species should have a detrimental effect on pre existing food chains

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5
Q

What does the competitive exclusion principle state?

A

That two species cannot occupy identical niches within a community

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6
Q

What is the argument to support the competitive exclusion principle?

A

One species will have a competitive advantage and survive at the expense of the other

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7
Q

What happens to minimise direct competition between species in nature?

A

Evolution via natural selection causing adaptations

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8
Q

What are four advantages that invasive species possess?

A
  • They have a larger fundamental niche
  • Faster reproductive rates
  • Lack a predator capable of limiting their survival
  • Have certain features suited to the new environment
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9
Q

Why were cane toads introduced?

A

To control the spread of the sugar cane beetle that was damaging crops

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10
Q

Why did the cane toad fail at limiting the beetle population?

A

It couldn’t reach the top of the sugar cane where the beetles live

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11
Q

What is the cane toad classified as?

A

An invasive species

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12
Q

What three reasons are the cane toads invasive?

A
  • has a wide diet and depleted the prey population for native insectivores
  • secretes a toxic chemical from its skin which has poisoned native predators
  • carried diseases which has transmitted to native species
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13
Q

Why have cane toads reproduced so successfully?

A

They have no natural predators

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14
Q

What three strategies have been implemented to control rabbit populations?

A
  • rabbit proof fences
  • hunting and poisoning and rabbit borne diseases
    -Destroying rabbit warrens
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15
Q

What effect have the rabbits had on native australian ecology?

A
  • killed native plant species by ringbarking
  • loss of said plants have left topsoil exposed and vulnerable to extensive erosion
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16
Q

Why were wild rabbits reproducing so quickly?

A

As australian conditions promoted a population explosion

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17
Q

When and where were European rabbits introduced?

A

To australia with the arrival of the first fleet

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18
Q

What are the three main methods of population control?

A

Physical
Chemical
Biological

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19
Q

What is physical control?

A

The removal or restriction of invasive species by manual or mechanical measures

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20
Q

What are examples of physical control?

A

Barriers, fences or removing habitats by trimming

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21
Q

How else can population numbers be reduced physically?

A

Hunting, trapping and culling

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22
Q

What is the problem with physical control methods?

A

Not species specific and can impede endemic wildlife

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23
Q

What is chemical control?

A

The use of chemical agents to limit population numbers and spread

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24
Q

What are examples of chemical control?

A

Herbicides, pesticides or other compounds

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25
Q

What is the disadvantages of chemical control?

A

Can be detrimental to local wildlife, expensive and have moderate specificity

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26
Q

When will the effect of chemical agents become more pronounced and why?

A

In higher trophic levels due to biomagnification

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27
Q

What is biological control?

A

Using a living organism to control an invasive species

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28
Q

What might the biological control do?

A

Eat the invasive species or cause it become diseased

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29
Q

Why must biological agents be assessed before release?

A

To ensure they do not become invasive themselves

30
Q

What are examples of biological control?

A

Vedalia beetle and myxoma virus

31
Q

Why must biological control agents be monitored?

A

For unintended side effects

32
Q

What is the cottony cushion scale?

A

A pest form australia that was released in california

33
Q

What did the cottony cushion scale do?

A

Damaged the californian citrus industry

34
Q

What is the vedalia beetle?

A

A predator from australia that was used in california as a biological control

35
Q

What did the vedalia beetle succeed in doing?

A

Limiting the numbers of the cottony cushion scale and minimise impact to the citrus industry

36
Q

What is biomagnification?

A

The process where chemical substances become more concentrated at each trophic level

37
Q

What is bioaccumulation?

A

The build of a chemical substance in the tissues of a single organism

38
Q

Why does biomagnification occur?

A

Because organisms at higher trophic levels must eat more biomass to meet their needs

39
Q

Why will higher order consumers experience increased contamination from a chemical substance?

A

As there energy transformations are only 10% efficient so they have to eat more to meet energy demands

40
Q

What is an example of a chemical substance which is biomagnifies?

A

DDT

41
Q

What is DDT?

A

A chemical pesticide that is sprayed on crops and subsequently washed into waterways at low concentrations

42
Q

What is the chemical description of DDT?

A

It is fat soluble and selectively retained in the tissues of an organism rather than being excreted

43
Q

What happens when DDT is sprayed on water to eliminate mosquito larvae?

A

It is taken up by the algae and passed on to primary consumers

44
Q

What happens at each subsequent trophic level to the concentration of DDT stored?

A

It increases due to increased food intake

45
Q

How did DDT affect fish?

A

It interfered with eggshell formation

46
Q

How did DDT affect birds?

A

Decreased survival rates of babies due to thinner shells

47
Q

When and why was DDT used as a chemical pesticide?

A

In the 1940s/50s to control insect borne diseases

48
Q

What did the use of DDT as an agricultural insecticide lead to?

A

The complete eradication of malaria in rich countries

49
Q

Why was using DDT in poor countries not as successful?

A

Eradication programs could not be sustained

50
Q

Why were eradication programs using DDT stopped?

A

Over safety and environment concerns

51
Q

What do they use for current interventions for malaria now?

A

Non spraying strategies like bed nets

52
Q

What are the four arguments supporting DDT spraying?

A
  • It is affordable and effective
  • Once it stopped malaria rates and deaths increased
    -When sprayed health costs associated with malaria decreased
  • alternative strategies are not as cost effective or successful
53
Q

What are the three arguments against DDT spraying?

A
  • associated with adverse health effects in humans
  • Persists in the environment for a long time
  • Is biomagnified in higher order consumers which is bad for ecosystems
54
Q

What are plastics?

A

A type of synthetic polymer found in clothes, bottles, bags and containers

55
Q

Why do plastics persist in the environment for centuries?

A

As most plastics are not biodegradable

56
Q

What is a macroplastic?

A

Large visible plastic debris (> 1mm)

57
Q

What is a microplastic?

A

Small plastic debris (<1mm)

58
Q

How can macroplastics be degraded into microplastics?

A

UV radiation and the action of waves

59
Q

Where will ocean currents concentrate plastic debris?

A

In gyres

60
Q

What are gyres?

A

Large oceanic convergence zones

61
Q

What does plastic debris do to the water?

A

Leach chemicals into it

62
Q

What does plastic debris absorb?

A

Toxic contaminants called persistent organic pollutants

63
Q

What absorbs more persistent organic pollutants and why?

A

Microplastics due to their smaller size and larger surface area

64
Q

How does plastics damage marine animals when they eat them?

A
  • causes bioaccumulation and biomagnification of persistent organic pollutants
  • damages their stomach and cause them to stop eating
65
Q

Where are the laysan albatross nests found?

A

In the north pacific gyre where large amounts of plastic debris is found

66
Q

How does the albatross ingest large quantities of plastic?

A

As they feed by skimming the ocean surface with their beak

67
Q

Why is the mortality rate of albatross chicks high?

A

As adults can regurgitate the plastics swallowed but the plants can’t

68
Q

Why do turtles eat a lot of plastic bags?

A

They mistake them for jellyfish

69
Q

How can plastic damage a turtle if ingested?

A

Plastic can be lodged in the oesophagus and cause future feeding problems

70
Q

How can plastic damage a turtle if it wraps around it?

A

Restricts movement and developmental growth

IB Biology (57 decks)

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