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A level Biology > 6.6 population and sustainability > Flashcards

6.6 population and sustainability Flashcards

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1
Q

define carrying capacity

A

the maximum population size that can be maintained over a period of time in a particular habitat

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2
Q

Define limiting factor

A

the factor whose magnitude slows down the rate of a natural process

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3
Q

What are the three phases of population growth

A

lag phase
log phase
stationary phase(carrying capacity)

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4
Q

describe the lag phase

A

may only be a few individuals and they are still acclimating to their habitat and at this point rate of reproduction is low and growth in population is slow

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5
Q

describe the log phase

A

resources are plentiful and conditions are good
reproduction happens quickly and the rate exceeds mortality
population size increases rapidly

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6
Q

describe the stationary phase

A

the population size has levelled out at the carrying capacity of the habitat and the habitat cannot support a larger population

the rate of reproduction and mortality equal and the population size remains fairly stable

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7
Q

What are the two different types of limiting factors

A

density independent
density dependant

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8
Q

describe how limiting factors can be density independent

A

they act strongly irresponsive of the size of the population for example low temperatures will kill the same proportion of the population irrespective of its size

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9
Q

Describe how limiting factors can be density dependant

A

where the factor increases the population more strongly as population size increases for example the availability of resources

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10
Q

what are the 2 different types of strategists

A

k-strategists and r-strategists

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11
Q

describe the characteristics of k-strategists

A

low reproductive rate
slow development
long lifespan
larger body mass

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12
Q

Define k-strategists

A

species whose population size is determined by the carrying capacity and limiting factors exert a more and more significant effect as population size gets closer to the carrying capacity

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13
Q

Describe the characteristics of r-strategists

A

high reproductive rate
quick development
short life span
small body mass

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14
Q

define r-strategists

A

its population can grow very quickly and surpass carrying capacity before the limiting effectors begin to have an effect and once carrying capacity has been surpassed there is a shortness of resources
‘boom and bust’

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15
Q

define interspecific competition

A

competition between individuals of different species

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16
Q

define intraspecific competition

A

competition between individuals of the same species

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17
Q

what can the relationship between predator and prey be described as

A

cyclic

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18
Q

Describe the predator and prey relationship

A

when prey populations get smaller predators have less food so their populations decrease
the decrease in predator populations leads to increased prey populations as theyre are less predators hunting them
and as prey populations begin to rise so do predator a they have more food

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19
Q

describe how intraspecific competition keeps population sizes relatively stable

A

If the population size drops there will be less competition and population size increases and vice versa

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20
Q

what experiment did Gause do

A

he grew two species of paramecium both separately and together as an investigation into interspecific competition

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21
Q

What did Gause conclude from his experiment

A

that the more overlap there was between two species niche’s results in more intense competition and one can be out-competed by the other and die out of become extinct in the habitat

22
Q

Define conservation

A

maintenance of biodiversity including diversity within species and maintenance of a variety of habitats and ecosystems

23
Q

define preservation

A

maintenance of habitats and ecosystems in their present conditions and minimising human impact

24
Q

What are some threats to biodiversity

A

over-exploitation
habitat destruction
species introduced to an ecosystem by humans that outcompete native species

25
Q

What are some conservation strategies

A

control predators and poachers
move individuals to enlarge populations
preserve habitats by preventing pollution
vaccinate individuals against disease

26
Q

Why conserve biodiversity

A

ethics
economic and social reasons

27
Q

define coppicing

A

the stem of a deciduous tree is cut close to the ground and once cut new shoots from the cut surface grow and mature into narrow stems

28
Q

define pollarding

A

cutting the stem higher up to prevent deer eating the emerging shoots

29
Q

what is rotational coppicing

A

dividing a forest into sections and cut one section each year so by the time they want to coppice again the new stems have matured and are ready to be cut

30
Q

Why is rotational coppicing beneficial

A

it is good for biodiversity
it lets more light in
provides different types of habitat

31
Q

Explain why in the past large-scale timber production was bad

A

Destroyed habitats, reduced mineral levels in soil and left soil susceptible to erosion.
Soil may run off into waterways polluting them

32
Q

describe modern sustainable forestry techniques

A

any tree harvested is replaced with another tree either grown naturally or planted
the forest must maintain its ecological function
local people should benefit from the forest
selective cutting
control pests and pathogens

33
Q

how do you manage fish stocks

A

fisheries and aquacultures

34
Q

what are the three principles for sustainable management of fisheries

A

fishing must take place at a level which allows it to take place indefinitely

fishing must be managed to maintain the structure

a fishery must adapt to changes in circumstances and comply with regulations

35
Q

What are the benefits and disadvantages of aquaculture rather than capture fisheries

A

aquaculture can provide sustainable fish stocks restricting impact on oceanic fish stocks

It is expected to feed more people than capture fisheries

36
Q

Where is the Terai region

A

In the south of Nepal

37
Q

What are some characteristics of the Terai region

A

It is made up of marshy grasslands, savannah and forests
it is densely populated and home to endangered species such as the bengal tiger

38
Q

What has been the effect of human activity in the Terai region

A

it has been under pressure for the expansion of agriculture into forested areas

grazing from farm animals, over exploitation of forest resources and replacement of traditional agricultural crop varieties

39
Q

Describe how the Terai region has been managed

A

the WWF were focused on conserving the forest landscape.

They introduced community forest initiatives local people had rights to exploit the forest as well as responsibilities to look after it.

Biogas schemes and wood-efficient stoves were introduced to reduce the demand for firewood

eradicating invasive species

creation of forest corridors between national parks

40
Q

Has the management of the Terai region been successful

A

yes, the tiger population has been steadily growing due to their use of the corridors

41
Q

Where is the Maasai Mara

A

It is a famous destination for wildlife watchers in Kenya

42
Q

Describe the characteristics of the Maasai Mara

A

It has large populations of antelopes and other large mammals
It has high endemic poverty but a lot of tourism so there had been a scope to develop conservation compatible land use that rewards local people financially and conserves habitats and species that are the basis of tourism

43
Q

Describe how the Maasai Mara is conserved

A

creation of National parks in 1945
Rest of the land was used agriculturally as many Maasai took tenure of small plots of the land
PWC - conservancies that set an area of land aside for conservation which have positive social and economic outcomes

44
Q

What are the negative consequences of conservancies

A

land-owners must move their livestock out during tourist season and their are constraints on how they use their land

45
Q

Describe how peat forms

A

where lack of oxygen prevents complete decomposition of organic matter usually in a waterlogged area

46
Q

what are some threats to peat bogs

A

Pressure from expansion of agriculture and forestry as well as landfill and peat extraction means that lowland peat bogs now covers less than a 1/10th of its original cover

47
Q

What has been the effect of human activity on the Galapagos islands

A

50% of vertebrae and 25% of plant species are endangered
2001 oil spill
death of 150 000 sharks/year
invasive species increasing competition for resources and can eat native species

48
Q

How are the effects of human activity managed in the Galapagos islands

A

at least 36% of coastal areas have become ‘No-Take’ zones
removal and prevention of invasive species
treat the problems caused by the invasive species

49
Q

What are some threats to biodiversity in the lake district

A

Spruce and pine in conifer plantations support limited biodiversity
invasive species such as rhododendron outcompete native species
cliff, rock and scree communities are damaged by climbers and walkers

50
Q

What are some solutions to the threats to biodiversity in the Lake district

A

varied planting
invasive species are physically removed
seasonal restriction on walking
farmers are paid to maintain hay meadows

51
Q

What are the impacts of humans on Snowdonia

A

farmers dig open drainage ditches which increase risk of flooding due to increased run off
conifers are planted as cash crop
heather is no longer burnt so that sheep can graze on it

52
Q

What are the solutions to the impacts on Snowdonia

A

blocking drainage ditches
burning controlled fires before heather gets too old and dry to prevent larger fires

A level Biology (25 decks)

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