populations and sustainability

Question 1

define carrying capacity

Answer 1

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

Question 2

define limiting factor

Answer 2

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

Question 3

population growth graph

what are the names of point a, b and c

Answer 3

a= lag phase ,

b= log phase , 
c= stationary phase ,

Question 4

describe lag phase

Answer 4

there may be a few individuals , which are still acclimatising to their habitat. at this point the rate of reproduction is low, and the growth in population size is low

Question 5

describe log phase

Answer 5

resources are plentiful , and conditions are good. reproduction can happen quickly, with rate of reproduction exceeding mortality. the population size increases rapidly

Question 6

describe stationary phase

Answer 6

the population has levelled out at the carrying capacity of the habitat . the habitat cannot support larger population. in this phase the rates of reproduction and mortality are equal. the populations size therefore stays stable , or fluctuates very slightly up and down in response to small variations in environmental conditions each year

Question 7

what are density independent limiting factors

Answer 7

these act just as strongly, irrespectively of the size of the population

for example, particularly low temperatures may kill the same size proportion of individuals in a population , irrespective of its size

Question 8

what are density dependent limiting factors

Answer 8

where the factor influences population more strongly as population size increases

for example , the availability of resources, like food , water , light, oxygen, nesting sites or shelter may decrease

Question 9

what are the two types of strategies

Answer 9

r strategies

k strategies

Question 10

r strategies and k strategies represent ….

Answer 10

two ends of a continuum of strategies adopted by living things

Question 11

describe k strategies and give examples

Answer 11

species whose population is determined by the carrying capacity. for those populations limiting factors exert a more significant effect as the population size gets closer to the carrying capacity, causing the population size to gradually level out

eg birds, larger mammals like humans , elephants and lions and larger plants

Question 12

name k strategies characteristics

Answer 12

• low reproductive rate
• slow development
• late reproductive age
• long life span
• large body mass

Question 13

describe r strategies and give examples

Answer 13

the population size increases so quickly that it can exceed carrying capacity of the habitat before the limiting factors start to have an effect . once the carrying capacity has been exceeded , there are no longer enough resources to allow individuals to reproduce or even survive . likewise an excessive build up of waste products may start to poison the species , and begin to die , entering a death phase
this type of population growth is known as boom or bust

for example , mice, insects, spiders, weds

Question 14

name r strategies characteristics

Answer 14

• high reproductive rate
• quick development
• young reproductive age
• short life span
• small body mass

Question 15

what is a predator

Answer 15

is an animal that hunts other animals (prey) for food

Question 16

describe the predator prey graph steps

Answer 16

1- when the predator population gets bigger, more prey are eaten
2- the prey population then gets smaller, leaving less food for the predators
3- with less food, fewer predators can survive and their population decreases
4-with fewer predators , fewer prey are eaten , and their population increases
5- with more prey , the predator population gets bigger and the cycle starts again

Question 17

describe competition

Answer 17

competition happens when resources ( like food or water ) are not present in adequate amounts to satisfy the needs of all the individuals who depend on the resources . if a resource is in short reply in an ecosystem, there will be competition between organisms for that resource
- as the intensity of competition increases, the rate of reproduction decreases whilst death rates increase

Question 18

what are the two types of competition

Answer 18

• interspecific competition

- intraspecific competition

Question 19

describe intraspecific competition

Answer 19

competition between individuals of the same species

as factors such as food become limiting , individuals compete for food. those individuals best adapted to obtaining food survive and reproduce , or die , this slows down population growth and the population enters the stationary phase

Question 20

describe interspecific competition

Answer 20

competition between individuals of different species

can affect both the population size of a species and the distribution of species in an ecosystem

Question 21

what is competitive exclusion principle

Answer 21

two species cannot occupy the same niche

Question 22

describe conservation

Answer 22

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

more of an active management process involving human intervention.this includes maintaining not just the diversity between species but also genetic diversity within species, and also maintaining a range of habitats and ecosystems

Question 23

describe preservation

Answer 23

maintenance of habitats and ecosystems in their present condition, minimizing human impact

keeping species and habitats as they are now. the approach known as preservation focuses on keeping things natural and eliminating any human effects on ecosystems that exist today

Question 24

what are the threats to biodiversity

Answer 24

a steadily increasing human population can threaten biodiversity through

• over exploitation of wild populations for food and for commerce
• habitat disruption and fragmentation as a result of more intensive agricultural practices, increased pollution, or widespread building
• species introduced to an ecosystem by humans that out compete other native species, leading to their extinction

Question 25

why do you conserve for ethical issues

Answer 25

they believe that every species has value and that humans have an ethical responsibility to look after them

Question 26

why conserve for economic and social reasons

Answer 26

many species have direct economic value when harvested - many plant sand animal species provide a valuable food source, and were originally domesticated from wild species. genetic diversity in wild strains may be needed in future to breed for disease resistance and improved yield in animals and plants, and drought tolerance in plants. likewise, new plant species may be domesticated for food use - natural environments are a valuable source of potentially beneficial organisms. many of the drugs we use today were discovered in wild plant species - natural predators of pests can act as biological control agents . this is preferable to causing pollution with artificial chemicals but few such species are yet being used. - indirect - species are responsible for pollinating crop plants, therefore harvest increases - ecotourism and recreation increase social and financial value

Question 27

describe suitable management of ecosystems

Answer 27

the human population is getting larger increasingly quickly , and we have had to use more intensive methods to exploit our environment for resources . such approaches can disrupt or destroy ecosystems , reduce biodiversity , and even completely remove the resource we originally wanted to harvest, our use of natural resources is not sustainable there is potential conflict between our need for resources and conservation

Question 28

what are the two ways of managing timber production

Answer 28

small scale | large scale

Question 29

what are the types of small scale timber production

Answer 29

coppicing rotational coppicing pollarding

Question 30

describe coppicing

Answer 30

provides a sustainable supply of wood. the stem of a deciduous tree is cut close to the ground .once cut, new shoots grow from the cut surface and mature into narrow stems. these can be used for fencing, firewood or furniture . after cutting them off, new shoots start to grow and the cycle continues

Question 31

describe pollarding

Answer 31

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

Question 32

describe rotational coppicing

Answer 32

to provide a constant supply of wood, woodland managers divide a wood into sections and cut one section each year by the time they want to coppice the first section again the new stems have matured and are ready to be cut

Question 33

what are the types of large scale timber management

Answer 33

clear felling | selective cutting

Question 34

describe clear felling

Answer 34

cut down and remove every tree from (an area). this destroys habitats on a large scale, reduce soil mineral levels and leave soil susceptible to erosion . trees usually remove water from soil and stop soil being washed away by rain. soil may run off into waterways , polluting them. trees also maintain soil nutrients levels throughout their role in the carbon and nitrogen cycles

Question 35

describe selective cutting

Answer 35

involves removing only the largest , most vulnerable trees, leaving the habitat broadly unaffected

Question 36

what are the two ways of managing fish stocks

Answer 36

fisheries | aquaculture

Question 37

describe fisheries

Answer 37

has high economic value , but not just from sales of fish but in providing livelihoods for millions of people - fishing must take place at a level which allows it to continue - fishing must be managed to maintain the structure , productivity , function and diversity of the ecosystem - must adapt to changes in circumstances and comply with local, national, and international regulations

Question 38

describe aquaculture

Answer 38

can also provide sustainable fish stocks. raising stocks of fish in aquaculture restricts the impact on oceanic fish stocks. aquaculture is expanding rapidly, particularly in the developing world, and is expected to feed more people than traditional capture fisheries in the near future

Question 39

balancing the conflict between conservation and human needs describe the terai region

Answer 39

- made of marshy Greenland, savannah and forest - many national parks - endangered species - under pressure form expansion of agriculture, grazing and over exploitation of resources - forest can provide a sustainable source of fuel, animal feed, food, building materials , agriculture , food - WWF focused on conservation of the forest

Question 40

balancing the conflict between conservation and human needs describe the massai mara

Answer 40

- attracts tourism, from conservation | - national parks

Question 41

controlling the effects of human activities describe the Galapagos islands

Answer 41

1-habitat disturbance, the population size increased placed huge demand on water, energy and sanitation services. more waste pollution - oil spill ruined ecosystems - land for agriculture 2-over exploitation for resources , killed half of tortoises -fishing for exotic species has depleted populations 3- effects of introduced species- out competing local species and alien species can eat native species or habitats , or bring disease to the island

Question 42

controlling the effects of human activities the Antarctica

Answer 42

1 krill-large amounts can be harvested very quickly , natural predators of krill cannot adapt to find krill everywhere else - therefore fishing must be conducted equally across all areas 2- protected areas - protected areas have been established to protect whales , within the sanctuary it is illegal to hunt or kill whales 3- albatrosses and petrels - these birds are threatened by human activities such as pollution, hunting , poaching for eggs, habitat destruction. and on the fishing line there are hooks which can be swallowed , therefore increasing deaths , to decrease deaths they can have bird scaring lines and weighted lines so there out of sight from birds

Question 43

the lake district name some threats to biodiversity and the solutions

Answer 43

1- threat - spruce and pine conifer plantations support limited biodiversity solution- recent initiatives have generated more varied planting and felling patterns , giving a mosaic of smaller stands of different aged trees 2-threat - invasive species spread into woodland , and outcompeting native species solution- they are physically removed by conservation workers 3- threat- hay meadows secure a rich diversity of flowers and grasses , but are under threat due to a preference away from hay meadow solution- farmers are paid to maintain hay meadows

Question 44

Snowdonia national park name some impacts by humans and the solution

Answer 44

impact -farmers dig open drainage ditches to dry the land . however this causes poor water quality in rivers, and rain flows quickly through the habitat, increased flood risk solution -to mitigate the effect , drainage ditches can be blocked by hay bales impact -conifers are planted as cash crops. however this dries out the moorland as the trees absorb water, and the roads have to be built to carry the wood away, compacting the land solution -when the trees are cut down, branches are used to block drainage ditches to slow water flow and hence keep the land moist impact - the moorland was burnt to provide a varied habitat for grouse, but when sheep grazed the land, burning was stopped. old heather burns easily, so accidental fires can be a high risk. if the peat sets on fire, that can damage the habitat on a large scale solution -burning controlled fires before heather gets too old and dry is important to prevent such damage

Question 45

describe conservation strategies

Answer 45

- establishing protected areas like national parks, green belts or SSSIs - can also involve giving legal protection to endangered species or conserving them ex situ in zoos or botanical gardens management strategies - raise carrying capacity by providing extra food - move individuals to enlarge populated , or encourage natural dispersion of individuals between fragmented habitats by developing dispersal corridors of appropriate habitat - restrict dispersal of individuals by fencing - control predators and poachers - vaccinate individuals against disease - preserve habitats by preventing pollution or disruption