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topic 8 > topic 7 > Flashcards

topic 7 Flashcards

1
Q

what is a population

A

group of organisms of the same species living in a particular area at a particular time that can potenttially interbreed.

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2
Q

what is a gene pool

A

range of alleles in a population

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3
Q

what is allele frequency

A

how often allele occurs in a population

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4
Q

what is the hardy-weinberg principle

A

predicts the frequency of alleles in a population that wont change from one generation to the next

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5
Q

what do the conditions of hardy weinberg apply to

A
  • large population
  • no immigration
  • no mutations
  • no natural selection
    no emigration
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6
Q

what does the p stand for in hardy weinberg

A

dominant allele

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7
Q

what does the q stand forr in hardy weinberg

A

the recessive allele

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8
Q

why might individulas within a population show a wide range of variation in a phenotype. (5 things)

A

-mutations
-random fertilisation
-independat segragation of homologus chromosomes
- crossing over
- environmental factors

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9
Q

what is evolution

A

a change in allele frequency over time

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10
Q

what way does evolution occur

A

natural selection

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11
Q

describe the process of natural selection

A

Evolution: change in allele frequencies in a population over time
1. Variation within a population due to mutations
2. Selection pressure e.g. predation, disease, competition à struggle for survival
3. Some organisms have phenotypes providing selective advantages (due to favourable allele(s))
4. These organisms are more likely to survive and reproduce, producing more offspring and
passing on their favourable allele(s) to the next generation i.e. differential levels of survival and
reproductive success

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12
Q

what do organisms need to fight for *******

A

-predation
- disease
- competiton

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13
Q

what is stabilising selection

A
  • selective pressure favours the mean phenotype
  • individuals with the extreme phenotype are less likely to survive and reproduce.
  • occurs in an unchanging environment
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14
Q

what is directional selection

A
  • selective pressure acts on the extreme phenotype.
  • so they are more likely to survive and reproduce.
  • due to a response to a change in the environment.
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15
Q

what is disruptive selection

A

when both the extreme phenotypes are favoured .
this can result in two different species.
environment favours both the extreme phenotypes

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16
Q

what are the two types of speciation

A

allopatric speciaiton
symptatric specition

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17
Q

what is speciation

A

the development of a new species from an existing speces

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18
Q

what happens to the population during speciation

A

they are reproductively isolated

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19
Q

how do new species arise

A

when members of a population are unable to interbreed to produce fertile offsprings

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20
Q

what type of isolation occurs in allopatric speciation

A

geographic isolation

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21
Q

what are examples that may cause geographic isolation

A

flooding
earthquake

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22
Q

what do physical barrieers prevent in allopatric speciation

A

inerbreeding between species

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23
Q

describe allopatric speciation

A
  • a population is geographically isolated and so are therfore reproductively isolated.
  • mutations causes genetic variation in each population
  • there are different selection pressures that acts on each population.
  • natural selection on favourable alleles.
  • alleleic frequency increases over time
    -memebers of the samee population cant inteerbreeed to produce fertile offsprings
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24
Q

what is sympatric speciation

A

when the populations arent gentically isolated

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25
Q

how does sympatric speciation occur

A

genetic variation due to mutations preventing membeers from of tthat population from breeding

26
Q

where can the mutations occur in sympatric speciation

A

in the chromosome number

27
Q

what are the different mechanisms that make individuals reproductively isolated

A
  • seasonal
  • mechanical
  • behavioural
28
Q

temporal/ seasonal

A

different mating/ breeding seasons

29
Q

mechanical

A

changes in genitalia which prevents successful mating

30
Q

behavioural

A

different courtship behaviour preventing mating

31
Q

what is genetic drift

A

when allele frequency of a popoulation changes over generations due to chance

32
Q

what other factor affects natural selection

A

genetic drift

33
Q

what is the founder effect

A

when smaller colonies forms from a larger one.

34
Q

what is a community

A

a population of diffferent species

35
Q

what is an ecosystem

A

a community plus all the non living components

36
Q

what is a niche

A

the role of a species within its habitat
like what it eats and where it feeds

37
Q

what are aibiotic conditions

A

non living components of an ecosystem

38
Q

what are biotic conditions

A

the living features of an ecosystem

39
Q

what is the carrying capacity

A

the maxiumum stable population an ecosysteem can support

40
Q

how can population size vary as a result of intercations between organisms

A

competition
aibiotic factors
predation

41
Q

what is interspecific competition

A

competition between organisms of dfferent species.

42
Q

what happens in interspecific competition

A

it reduces resources avaliable to both species
when one species is better adapted it will out-compete the others

43
Q

what is intraspecific competition

A

competition between organisms of the same species

44
Q

what does a small population mean in terms of copetition

A

results in less competition

45
Q

what is predation

A

when an organism kills and eats another organism

46
Q

increased predator population size à more prey eaten à prey population falls à less
food for predators à predator population size falls à prey population rises à predator
population rises again…

A

increased predator population size à more prey eaten à prey population falls à less
food for predators à predator population size falls à prey population rises à predator
population rises again…

47
Q

what is succession

A

process by which an ecosystem changes overtime

48
Q

what is a pioneer species

A

the first species to colonise

49
Q

what do pioneer species do

A

they change the aibiotic consitions so that the environment is less hostile
- which allows the environment to be more sutibale for other speciees with different species

50
Q

what happens to the biodiversity as succesion goes on

A

it increases

51
Q

what is the climax community

A

the final, complex, stable community

52
Q

why are pioneer species able to grow in aibiotic conditions

A

they are better adapted

53
Q

how do thee pioneer species change the aibiotic conditions

A

they die and microorganisms decompose dead matter to humus
in order to form basic soil

54
Q

what is secondary succesion

A

when land has been cleared
e.g a fire

55
Q

what is primary succession

A

land that has been newly formed or exposed

56
Q

what is plagioclimax

A

when succession is stoppedd artifically by human activity so stops a climax community from forming.

57
Q

how can you manage succession

A

conservation

58
Q

what is the purpose of conservation

A

in order to preserve the community in its current stage of succesion

59
Q

what is conservation

A

protection and management of species and habitats in a sustainable way

60
Q
A
61
Q
A

topic 8 (4 decks)

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