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Biology OCR A A-level yr 12 > populations and sustainability > Flashcards

Flashcards in populations and sustainability Deck (46)
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1
Q

what is a limiting factor?

A

an environmental resource or constrain that limits population growth

2
Q

a population growth curve can be operated into three different phases. Explain these phases?

A
  • first phase of slow growth. Small numbers of individuals initially present reproduce increasing total population. As birth rate is higher than death rate, the population increases in size.
  • second phase of rapid growth. The number of breeding individuals increases and the total population multiplies exponentially. No constraints act to limit population explosion.
  • third phase of stable state (carrying capacity). Further population growth is prevented by external constraints (limiting factors). Population size fluctuates but overall size remains relatively stable.
3
Q

what is an abiotic factor?

A

non-living factor e.g temp, humidity, water

4
Q

what is a biotic factor?

A

living factor e.g disease, predator, prey

5
Q

what is carrying capacity?

A

the maximum population size an enviroment can support

6
Q

how does a population size remain stable?

A

when number of births and deaths are approximately equal.

7
Q

types of limiting factors?

A
  • abiotic
  • biotic
  • migration
8
Q

2 types of migration?

A

immigration and emigration

9
Q

what is immigration?

A

the movement of individual organisms into a particular area increases population size.

10
Q

what is emigration?

A

the movement of individual organisms away from a particular area decreases population size

11
Q

what are density independent factors?

A

factors that have an effect on the whole population regardless of its size e.g each quakes, fires, storms. These factors could remove whole populations of species in an area.

12
Q

Unlike other species why does the population size of humans grow exponentially?

A

there is an imbalance between birth rate and death rate due to advances in medicine and agriculture and the industrial revolution.

13
Q

how do you calculate population percentage growth?

A

(population change during the period/ population at ther start of the period) times 100

14
Q

what are the two types of competition? (biotic factors)

A

interspecific competition and intraspecific competition

15
Q

what is interspecific competition?

A

competition between different species e.g predation

16
Q

what is intraspecific competition?

A

competition between the same species

17
Q

Describe interspecific competition?

A

this interaction causes reduction of resource available for organisms of each species. However if one species is better adapted, the less adapted species will be outcompeted. If conditions remain, the species population will decline- competitive exclusion principle e.g squirrels

18
Q

what is competitive exclusion principle?

A

two species competing for limited resources. The one that uses resources more effectively will ultimately eliminate the other.

19
Q

why did the grey squirrels dominate the red squirrels?

A

grey squirrel can eat a wider range of food and can store more fat increasing change of survival and ability to reproduce

20
Q

Describe intraspecific competition

A

availability of the resource determines the population size. Greater availability, larger population. This leads to fluctuations.

21
Q

The intraspecific graphs can be separated into three stages. Explain these stages.

A

stage 1- when resource is plentiful, enough resource to survive and reproduce causing increase in population
stage 2- increased population causes limited resources which is not enough for survival and reproduction causing population to decrease
stage 3- less completion as the population. More resources for survival and reproduction causing population growth.

22
Q

The predator prey relationship graph can be separated into 4 stages. Describe these stages.

A

stage 1- increase in prey population provides more food for predators, allowing them to survive and reproduce causing increase in predator population.
stage 2- increase predator population causes more prey eaten, causing decline in prey population. Death rate of prey is higher than birth rate.
stage 3-reduced prey population cannot support predator population. Intraspecific competition for food increases causing decrease in predator population
stage 4- reduced predators, less killed prey killed. More prey survive and reproduce, increasing population.

23
Q

Why is the predator- prey relationship not simple?

A

other factors influence populations size e.g presence of other predators and prey food availability (plants)

24
Q

what is conservation?

A

the maintenance of biodiversity through human action or management. Conversation approaches also includes reclamation- process of restoring damaged ecosystems.

25
Q

what is sustainable development?

A

management of ecosystems so that natural resources in the can be used without running out

26
Q

what is preservation?

A

protection of an area by restricting or banning human interference, so that the ecosystems is kept in the original state.

27
Q

what are the three reasons for conservation. as important?

A

economic, social, ethical

28
Q

explain the economic importance of conservation

A

to provide resources that humans need to survive and to provide income e.g rainforests provide drugs

29
Q

explain the social importance of conservation

A

to enjoy the natural beauty of wild ecosystems as well as using them for activities which are beneficial to health by providing relaxation and excising

30
Q

explain the ethical importance of conservation

A

all organisms have a right to exist, and most play a role in the ecosystem. Moral responsibility for future generations to conserve the wide variety of existing natural ecosystems

31
Q

what is a sustainable resource/

A

a renewable resource that is being economically exploited in such a way that will not run out.

32
Q

what are the aims of sustainability?

A
  • persevere the environment
  • ensure all natural resources are available for future generations
  • allow humans in all societies to live comfortably
  • enable less economically developed countries to develop through exploiting their natural resources
  • create a more even balance in the consumption of these resources between more economically developed countries AND LEDS
33
Q

how else can we sustainably manage resources?

A

resources should be uses more efficiently so finite resources aren’t used up so quickly.

34
Q

how can we manage the rate at which finite resources are used?

A

as technology advances, alternatives can be developed. However this can be costly and have negative environmental effects

35
Q

what is coppicing (small scale sustainable timber production)?

A

technique where tree trunk is cut close to ground. New shoots can form and mature

36
Q

what is the purpose of shoots from coppicing?

A

fencing

37
Q

rotational cooping often occurs in managed woodlands, what is it?

A

woodland is divided into section and trees are only cut into particular sections until all are coppiced. Coppicing then occurs in another area allowing time for growth. It is a cycle.

38
Q

what is pollarding?

A

technique similar to coppicing, but the trunk is cut higher up so animals cannot eat new shoots as they appear.

39
Q

Describe large scale sustainable timber production

A

technique of felling is used on large areas of forest. Felled trees are destroyed and will not regrow

40
Q

How is large scale timber production kept sustainable?(5 reasons)

A
  • practise selective cutting, only remove large trees
  • replace trees by replanting rather than waiting for natural regeneration to ensure biodiversity, mineral and water cycles are maintained.
  • plant trees an optimal distance apart to reduce competition for higher yield as more wood is produced per tree
  • manage pests and pathogens to maximise yields
  • ensure areas of forest remain for indigenous people.
41
Q

what are the disadvantages of the felling technique?

A

habitats are destroyed, soil minerals are reduced and the bare soil left is susceptible to erosion.

42
Q

How has over fishing been limited? (4 reasons)

A
  • government regulations
  • larger mesh size
  • allowing commercial and recreational fishing only at certain times of the year
  • fish farming
43
Q

how do government regulations limit overfishing?

A

e.g fisheries policy, fishing quotas provide limits on the numbers of certain fish that are allowed to be caught in a particular area. To maintain natural population of these species that allows fish to reproduce and maintain population

44
Q

how do bigger mesh sizes limit overfishing?

A

so immature fish can escape, only mature fish are caught thus allowing breeding to continue

45
Q

how does allowing commercial and recreational fishing only at certain times of the year limit overfishing?

A

This protects the breeding season of some fish species and allows fish levels to increase back to sustainable level.

46
Q

how does fish farming limit overfishing?

A

prevents loss of wild species. It is easier to fish farms vegetarian fishes but when farming carnivorous fish it isn’t sustainable

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