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Alevel Biology > 6.6 > Flashcards

6.6 Flashcards

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1
Q

what determines the size of a population

A

balance between death rate and rate of reproduction

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2
Q

what is happeniong to a population in lag phase

A

may only be a few individuals which are acclimitising to their habitat, rate of reprodution is low and growth in population is slow

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3
Q

what is happeniong to a population in log phase

A

resoirces are plentiful and conditions are good, quick reproduction, with rate exceeding that of mortality, population size rapidly increases

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4
Q

what is happeniong to a population in stationary phase

A

population size leveled out at carrying capacity, habitat can no longer support large population, rate of reproduction and mortality are equal, population therefore stays stable or very slightly flucutaes depending on small variations in environment each year

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5
Q

what is carrying capacity

A

max population size that can be maintained over a period in a certain habitat

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6
Q

why can a habitat that reached carrying capacoty not support a larger population

A

due to limiting factors

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7
Q

what are density independent limiting factors + examples

A

act just as strongly, irrespective of population size, e.g. very low temp may kill same proportion of individuals in a population, irrespective of its size

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8
Q

what are density dependent limiting factors and example

A

factor influences population more strongly as population size increases, e.g. availability of resources like food, water and light may decrease, carrying capacity is upper limit that these factors place on population size§

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9
Q

What the the 2 different strategies and what is a strategy

A

r-Strategies and k-Strategies represent 2 ends of a continuum of strategies adopted by living things

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10
Q

What are k-Strategists

A

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

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11
Q

what are examples of k-strategists and what characteristics do they often exhibit

A

birds, larger mammals (humans, elephants), larger plants, low reproductive rate, slow development, late reproductive age, long lifespan, large body mass

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12
Q

what are r-strategists

A

population size increases so quickly that it can exceed carrying capacity of habitat before limiting factors start to have an effect, once carrying capacity has been exceeded, no longer enough resources to allow individuals to reproduce or survive and excessive build up of waste poison species and they begin to die (entering death phase), this population growth know as boom and bust

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13
Q

examples pf r-strategists and characteristuics they exhibit

A

mice, insedcts, spiders, weeds, hgih reprodctive rate, quick development, young reproductive age, short life span, small body mass

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14
Q

what is the most important influence on population growth

A

physical rate at which individuals can reproduce

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15
Q

what is a predator

A

an animal that hunts other animals (prey) for food

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16
Q

what can predation act as a limiting factor for

A

a prey’s population size which can inturn effect predator population size

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17
Q

what are 5 steps of predator-prey relationship

A
  1. when predator population grows, more prey eaten, 2. prey population gets smaller, leaving less food for prey 3. with less food, fewer predators survive and their populations decreases 4. with fewer predators, fewer prey eaten and their population increases 5. more prey, predator population grows and cycle strats again
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18
Q

when does competition happen

A

when resources like food and water are not present in adequate amounts to satisfy needs of all individuals who depend on those resources, e.g. if resource in ecosystem in hort supply there will be competition between organisms for that resource

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19
Q

what happens as intensity of competition increases

A

rate of reproduction decreases (as fewer organisms have enough resources to reproduce), whilst death rate increases (as fewer organsisms have enough to survive)

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20
Q

what are the 2 types of competition

A

infraspecific (within same species), interspecific (between species)

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21
Q

what is intraspecifc competition

A

competition between those in same species. Factors like food supply become limiting, individuals compete for food. Those best adapted survive and reproduce while those not well adapted fail to reproduce and die, population enters stationary phase

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22
Q

how does intraspecific competition keep population stable in stationary phase

A

if population size drops, competition reduces and population size increases, if population size increases, competition increases and population size drops

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23
Q

what is interspecific competition

A

happens between individuals of different species and can effect both population size of species and distribution of species in an ecosystem

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24
Q

what does 2 species having similar niches mean for interspecifc competition

A

the more similar niche the more competition , e.g. if 2 have exact same niche 1 will out compete the other

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25
Q

what is competitive exclusion principle

A

2 species cannot occupy same niche and live in same habitat, 1 will out compete the other

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26
Q

rather than extinction of 1 species what does interspecificc competition sometimes lead to instead

A

1 species having much smaller population than other wspecies

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27
Q

what is preservation

A

keeping species and habitats as they are now, focuses on keeping things natural and eliminating any human effects on ecosystem that exist today

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28
Q

what is conservation

A

more active management process involving human intervention, change in ecosystems in inevitable, both through natural succession and human activity, conservation programmes focus on maintaining or improving biodiversity, including diversity between species and genetic diversity and maintainng range oif habitats and ecosystems

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29
Q

how can an increasing human population threaten biodiveristy (3)

A

over-explotation of wild populations for food, sport and for commerce, Over-explotation - species harvested faster rate than they can replenish themselves, habitat disrutpion and fragmentation due to more intensive agriculture practices, increasing pollution and widespread buildings, species introduced into ecosystem by humans that out compete native species causing their extinctioin

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30
Q

what does successful conservation require

A

consideration of social and economical costs to local community and effective education and liaison with community

31
Q

what are examples of conservation

A

national parks, green belt land, site of special scientific interest (SSSIs), or giving legal protection to endangered species or ex situ conservation in zoo/botanic garden

32
Q

what are 6 management strategies to maintain stablr community in conservation programmes

A

raise carrying capacity by providing extra food, more individuals to enlarge populations or encourage natural dispersion of individuals between fragmented habitats by creating dispersal corridors, restrict dispersal of individuals by fencing, control predators and poachers, vaccinate individuals against disease, prevent pollution or dispertion or intervene to reduce progress of succession

33
Q

why is simple management sometimes inappropriate and what is done instead

A

disruption of community may hav gone too far and not clear which species were originally there and succession will take a long time before new community can live there, short cutting requires detailed knowledge of species involved but if environment remained quite stable can clean up pollution and remove unwanted species and replace disrupted community with slightly different community

34
Q

what are the ethics of conservation

A

som believe humans have ethical responsibility to look after animals, but there are arguments against supporting burning of fossil fuel of economic reasons

35
Q

what are economic reasons for conservation

A

many species have direct economic value when harvested (easy to measure) and others may have economic value in future but not discovered yet (this value hard to estimate)

36
Q

3 examples of economic reasons for conservaion

A

many plants and animal species are 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 improve yield in animals and plants an drought tolerant plants and new plant species domesticated for food sue, natural environments valuable source of potential beneficial organisms, e.g. many drugs come from plants, natural predators of pests can act as biological control agents which is preferable to use of chemicals

37
Q

how do many species have an indirect encomic value

A

insects responsible for pollinationg crop plants, wihtout them harvest may fail and farmers would go out of business

38
Q

what are social reasons for conservation

A

ecotourisms and recreation in countryside have signifcant social and financial value which comes from aesthetic value of living things, ecotourisms depends on maintenance of biodiversoty

39
Q

what is the impact of growing human population

A

we use more intensive methods to exploit environments resources which can destory ecosystems, reduce biodiversity, remove resources completely which isnt sustainable

40
Q

what is coppicing

A

small scale timber production providing sustainable supply of wood, stem of a deciduous tree cut close to ground, once cut, new shhoots grow from cut surface and mature into narrow stems which can be used for fencing, firewood and furniture, after cutting thrm off new shoots start to grow again and cycle continues

41
Q

what is pollarding

A

same idea as coppicing but stems cut higher up to prevent deer eating emerging shoots

42
Q

what is rotational coppicing

A

divide woods into sections and use a different section each year, by the time there at the first section again new stems will have matured and be ready to be cut, in each section some trees are left to grow larger called standards and are eventually cut when larger piece of timber needed

43
Q

why is rotational coppicing good for biodiversity

A

left unmanaged, woodland goes through process of succession, blocking out light to woodland floor and reducing number of species growing there, in rotational coppicing different areas of woodland provide different types of habitat, letting in more light and incrasing number and diversity of species

44
Q

what did large scale timber production used to involve and what are issues with it

A

clear felling all the trees in one area which could destroy habbittas on a large scale, reduce soil mineral levels and leave soil susceptible to erosion, tree usually removes water from soil and stop soil being washed away by rain, soil may run off into waterways, polluting them, trees also maintain soil nutrient levels through their role in carbon and nitrogen cycles but this is now rarely used in uk

45
Q

how does large scale timber production happen these days

A

modern sustainable forestry avoids this by working on following principles: any tree harvested is replaced by another tree either grown naturally or planted, forest as a whole must maintain its ecological function regarding biodiversity, climate, minerals and water cycles, local people should benefit from the forest

46
Q

what does selective cutting invovle

A

removing only the largest, most valuable trees, leaving habitat broadly unaffected

47
Q

what does sustainably managing forests involve

A

balancing conservation against need to harvest wood, both to maintain biodiversity and to make woodland pay for itself , if each tree supplies more wood, fewer trees need to be harvested

48
Q

how is sustainable forest management managed

A

foresters control pests and pathogens, only plant particular tree species where they know they will grow well, position trees at optimal distance apart as if too close too much competition for light and trees will grow thin and tall meaning poor quality timber

49
Q

what are the 1/3 of the principles proopsed by marine stewardship council for sustainable management of fisheries

A

fishing must take place at a level which allows it to continue indefinitely, over-fishing must be avoided as it can reduce fish population to zero, if over-fishing occurs, reducing fishing to let stocks recover can rapidly increase productivity and good for profitability, given high stock values can support a more efficient harvest, optimum is to maintain fish populations at carrying capacity of their environment, while fishing continues to harvest fish in excess of that capacity

50
Q

what are the 2/3 of the principles proopsed by marine stewardship council for sustainable management of fisheries

A

fishing must be managed to maintain strucutre, productivity, function and diversity of ecosystem meaning there should not be permanent damage to local habitat and any effect on dependant species is minimised

51
Q

what are the 3/3 of the principles proopsed by marine stewardship council for sustainable management of fisheries

A

fishery must adapt to changes in circumstances and comply with local, national and international regulations

52
Q

how can aquaculture provide sustainable fish stocks

A

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

53
Q

why is it necessary to balance competing requirements for natural resources by humans and other living things

A

to help secure sustainable use of natural resources which is compatible with conservation, 2 examples of this are the terai region and Maasai mara

54
Q

what is in the terai region

A

marshy grassland, savannah and forests, its densely populated and home to endangered species including bengal tiger and one-horned rhino, many national parks in this region

55
Q

what has happened in last 10 years to terai region

A

forests here under pressure from expansion of agriculture into forest areas, grazing from farm animals, over-explotation of forest materials and replacement of traditional crop varieties with modern ones. So, WWF found rural livelihoods are dependant on the forests which also home to many endangered species, the forests provide local people with sustainable fuel source, animal feed, food, building materials, agriculture, household tools and medicines

56
Q

as a result of the terai region being useful for locals what has happened (terai-arc project)

A

WWF and nepalese government focused on conservation of forest landscape as a whole, to ensure conservation with development they introduced community forestry initiatives where local people can exploit forest as well as have responsibility to look after it, these community groups helped create forrest corridors between national parks which are essential to dispersal snd survival of tigers, as well as taking initiative in counteracting poachers and illegal felling. Forestry work also developed and diversified on and off farm activity, built entrepreneurial skills and stimulated small credit and marketing schemes. the WWF scheme introduced biogas plants and wood-efficient stoves to reduce demand for firewood, also constructing watering holes, monitoring endangered species and removing invasive species. As a result tiger population is steadily growing

57
Q

what is the Maasai mara

A

in kenya, large populations of antelope and other large mammals, it combines high endemic poverty with abundant wildlife populations that attract tourism their has been scope to develop conservation compatible land that rewards locals financially whilst conserving habitats and species for basis of tourism

58
Q

what has happened in Maasai Mari as a result of agriculture

A

wildlife dropped by 65% in 30years and sheep and goat population increased, in 2005 some land owners combined their land for conservation in order tp get tourism income, they are paid proportionally to the area of land they leave to conservation, these conservancies have has positive social and conservation outcomes

59
Q

what are some negative consequences of conservancies

A

land owners must move their live stock out during tourist season leading to increased stocking densities outside the reserve where no one receives PWC money, also, land owners often forced to settle elsewhere and constraints on how they use their land

60
Q

how does livestock impact conservation

A

can have large impact but limited livestock grazing can have positive effects on diversity and as livestock important in Maasai culture it is integrated alongside conservation

61
Q

what are effects of human activity non populations

A

habitat destruction, competition for natural resources, hunting and population

62
Q

What is Galapagos islands

A

has a high number of native species but many species now endangered due to humans increased demand for marine products and tourism

63
Q

how has human acitivyt caused habitat disturbance in Galapagos

A

population size increase placed large demand on water, energy and sanitation services, more waste and pollution produced and oil demand increased (oil spills kill marine life), buildings and land for agriculture has caused destruction and fragmentation of habitats (forest of scalesia trees almost all eradicated for agriculture land)

64
Q

how has human acitivyt caused over exploitation of resources in Galapagos

A

whaling boats and fur traders killed 200 000 tortoises in half a century, more recent boom in fishing for exotic fish caused depleted populations and depletion of sea cucumber had drastic effects on underwater ecology and market for shark fin has lead to death of 150 000 sharks around the islands

65
Q

what is effects of introduced species in Galapagos

A

outcompete local species or eat native species or bring disease to island, e.g. cats hunt and eat lava lizards and young iguanas, goats destroy tortoises nesting sites. Invasive species can endanger all other species

66
Q

how has Galapagos managed effects of human activity

A

Darwins research station adopted 2 methods- to prevent introduction and dispertion of new species and to treat problems caused by these species, they searched arriving boats and tourists for foreign species and culling used against over populated species. Resisdants and tourists educated on their impact and 36% of coastal zones are no take areas where no extraction of resources is permitted

67
Q

how has antarctic been effected by human activity

A

not too badly effected but increase in scientists and fishing could have effect

68
Q

what are krill in the antarctic, why and how do we protect them

A

shrimp like organisms that provide food for whales, seals, penguins, albatrosses and squid, large amounts of krill can be harvested quickly due to advancing technology. fishing boat congregate where Large numbers of krill are but the animals that feed on krill can not adapt as easily to find krill elsewhere. to avoid over exploration their is a catch size limit in some areas and when reached fishing must be conducted equally across all areas to avoid impact on predators

69
Q

what areas are protected in the antarctic

A

to protect whales the southern icean whale sanctuary was established coving summer feeding grounds of 80-90% of worlds whales, within this its illegal to hunt and kill whales

70
Q

what are albatrosses and petrels in antarctic why and how do we protect them

A

birds threatened by pollution, hunting and poaching for eggs, habitat destruction and non native predators and long fishing lines. They get stuck on bait hooks and can swallow these hooks, to reduce the number of deaths boats should use burd scaring lines and streamers (weighted lines that sink lower down) or fish at night

71
Q

how has Lake District been impacted by human activity

A

graxzing has caused delfective succesive and without this climax communities would be reached, farmers are given incentives to reduce chemical use, safeguard hedges and care for medows and wetlands

72
Q

what are 3 threats to biodiversity in lake district and what is solution

A

spruce and pine in confier plantations support limited biodiversity, recent initiatives generated more varied planting patterns, giving trees of different ages, invasive species like rhododendron have escaped gardens ad outcompeted native species in woodland, physically removed by conservation workers, limestone pavement lets rare ferns and butterflies species live in gaps, the pavement is legally protected

73
Q

what is snowdonia national park and humans impact on it

A

attracts walkers and climbers, paths maintained to ensure no rare plants stepped on, rubbish is dropped by walkers which can cause path erosion, sheep and goat grazing can impact rare plants, farmers encouraged to plant hedges

74
Q

what are 2 impacts by humans and solutions in snowdonia

A

farmers dig open drainage ditches to dry land increasing flood risk, drainage ditches can be blocked with hay bales, conifer plated as cash crops but this dries out moorlands, when trees cut down branches block drain ditches to slow water flow and keep land moist

Alevel Biology (25 decks)

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