populations and sustainability

Question 1

what is a limiting factor?

Answer 1

an environmental resource or constrain that limits population growth

Question 2

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

Answer 2

• 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.

Question 3

what is an abiotic factor?

Answer 3

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

Question 4

what is a biotic factor?

Answer 4

living factor e.g disease, predator, prey

Question 5

what is carrying capacity?

Answer 5

the maximum population size an enviroment can support

Question 6

how does a population size remain stable?

Answer 6

when number of births and deaths are approximately equal.

Question 7

types of limiting factors?

Answer 7

• abiotic
• biotic
• migration

Question 8

2 types of migration?

Answer 8

immigration and emigration

Question 9

what is immigration?

Answer 9

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

Question 10

what is emigration?

Answer 10

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

Question 11

what are density independent factors?

Answer 11

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.

Question 12

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

Answer 12

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

Question 13

how do you calculate population percentage growth?

Answer 13

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

Question 14

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

Answer 14

interspecific competition and intraspecific competition

Question 15

what is interspecific competition?

Answer 15

competition between different species e.g predation

Question 16

what is intraspecific competition?

Answer 16

competition between the same species

Question 17

Describe interspecific competition?

Answer 17

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

Question 18

what is competitive exclusion principle?

Answer 18

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

Question 19

why did the grey squirrels dominate the red squirrels?

Answer 19

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

Question 20

Describe intraspecific competition

Answer 20

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

Question 21

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

Answer 21

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.

Question 22

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

Answer 22

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.

Question 23

Why is the predator- prey relationship not simple?

Answer 23

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

Question 24

what is conservation?

Answer 24

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

Question 25

what is sustainable development?

Answer 25

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

Question 26

what is preservation?

Answer 26

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

Question 27

what are the three reasons for conservation. as important?

Answer 27

economic, social, ethical

Question 28

explain the economic importance of conservation

Answer 28

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

Question 29

explain the social importance of conservation

Answer 29

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

Question 30

explain the ethical importance of conservation

Answer 30

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

Question 31

what is a sustainable resource/

Answer 31

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

Question 32

what are the aims of sustainability?

Answer 32

• 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

Question 33

how else can we sustainably manage resources?

Answer 33

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

Question 34

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

Answer 34

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

Question 35

what is coppicing (small scale sustainable timber production)?

Answer 35

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

Question 36

what is the purpose of shoots from coppicing?

Answer 36

fencing

Question 37

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

Answer 37

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.

Question 38

what is pollarding?

Answer 38

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

Question 39

Describe large scale sustainable timber production

Answer 39

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

Question 40

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

Answer 40

• 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.

Question 41

what are the disadvantages of the felling technique?

Answer 41

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

Question 42

How has over fishing been limited? (4 reasons)

Answer 42

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

Question 43

how do government regulations limit overfishing?

Answer 43

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

Question 44

how do bigger mesh sizes limit overfishing?

Answer 44

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

Question 45

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

Answer 45

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

Question 46

how does fish farming limit overfishing?

Answer 46

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