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alevel biology ocr > evolution/natural selection/variation/adaptations > Flashcards

evolution/natural selection/variation/adaptations Flashcards

1
Q

what is evolution

A

the gradual change in heritable traits of organisms many millions of years (successive/several generations)

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2
Q

what is evolution (as a genetic def)

A

a change in the allele frequency of a populations gene pool over successive generations

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3
Q

heritable traits are encoded for by … and may be transferred

A

genes and may be transferred between generations as alleles

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4
Q

darwins obs: organsism produce…

A

more offspring than survive

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5
Q

darwins obs: theres variation in…

A

the characteristics of members of the same species

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6
Q

darwins obs: some of these characteristics can be…

A

passed on from one generation to the next

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7
Q

darwins obs: individuals that are best adapted….

A

to their environment are more likely to survive

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8
Q

darwins obs: populations do not…

A

fluctuate significantly

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9
Q

What is the name of the mechanism by which evolution occurs

A

natural selection

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10
Q

describe the process of natural selecion (3)

A

a new ALLELE arising from random mutation

leads to
increased REPRODUCTIVE SUCCESS is inherited by the next generation.

Over many generations, the new allele increases in FREQUENCY in the population

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11
Q

principals of NS: over pro…..

A

over production leads to competition

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12
Q

principals of NS: variation due to

A

mutaion

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13
Q

principals of NS: selection via

A

adaption (surival of the fittest)

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14
Q

principals of NS: breed and pass…

A

on characteristics

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15
Q

what is a selection pressure (2)

A

a factor which affects an organisms chance of survival or ability to reproduce

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16
Q

what does density dependent mean

A

the factors have a greater impact in denser populations

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17
Q

what does density independent mean

A

the factors are not facilitated by high population density, affects all populations regardless of density

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18
Q

what are the 5 density dependent factors/selection presures
(p,r,n,d,w)

A

predators
availability of resources
nutrient supply
disease (pathogenic spread)
accumulation of wastes

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19
Q

what are the 3 density independent factors/selection pressures

A

abiotic factors
weather conditions

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20
Q

offspring generally appear similar to their parents deducting that

A

characteristics are passed on to the next generation

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21
Q

organisms have the ability to produce large numbers of offspring and populations in nature tend to remain relatively stable deducting that

A

there is a struggle for existence

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22
Q

no two individuals are identical and organisms have the ability to produce large numbers of offspring and populations in nature tend to remain relatively stable deducting that

A

individuals with beneficial characteristics are among few who survive

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23
Q

what are the types of evidence for evolution

A

comparative anatomy (homologous structures)
paleontology(fossils)
comparative biochemistry
molecular biology

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24
Q

what are homologous structures

A

anatomical features that are similar in basic underlying structure despite being used in different way

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25
Q

what is adaptive radiation

A

the diversification of a group of organisms into forms filling different ecological niches

26
Q

what is divergent evolution

A

that organisms all diverge from a common ancestor with different sets of features even though they have the same homologous structure

27
Q

what is an example of comparative anatomy

A

the pentadactyl limb: mammals, birds, amphibians and reptiles share a similar arrangement of bones in their appendages based on a five digit/component/element limb

28
Q

the homologous structures provide evidence for

A

divergent evolution

29
Q

what is meant by rock strata

A

when remains are preserved in rocks that correspond to different geological eras

30
Q

what do fossils show

A

usually bones but sometimes soft tissue or footprints

31
Q

what are fossils

A

preserved remains/traces of any organism

32
Q

how does fossil evidence support the idea that evolution has taken place

A

fossils have changed over time
fossils can be dated
fossils can show intermediate forms and sequences

33
Q

what is a fossil record

A

totality of fossils discovered and undiscovered

34
Q

how do fossil records provide evidence

A

they reveal the features of an ancestor for comparison against living descendants and shows that over tune changes have occurred in the features of living organisms

35
Q

what is intraspecific variation

A

Intraspecific variation is variation within a species

36
Q

what are the causes of variation

A

nature (genetics) and nurture (the environment)

37
Q

what is interspecific variation

A

variation between species

38
Q

What are the four main sources of genetic variation

A

mutation, random mating, random fertilisation and recombination of homologous chromosomes during meiosis

39
Q

What term is given to variation which falls into clear groups? E.g. blood groups

A

discontinuous variation

40
Q

which type of variation has the effect from few genes

A

discontinuous

41
Q

which type of variation is polygenic

A

continuous

42
Q

which type of variation is effected by the environment

A

continuous

43
Q

what type of variation is not effected by the environment

A

discontinuous

44
Q

What term is given to variation which can be any value within a given range? E.g. human height

A

continuous variation

45
Q

Human populations use drugs to control infectious diseases. Natural selection in bacteria has led to what problem relating to this?

A

antibiotic resistance

46
Q

antibiotic resistance: bacteria reproduce very rapidly which….

A

reproduce/replicate so dna alters to become resistant to antibiotics

47
Q

antibiotic resistance: exposure to antibiotics which is the

A

selection pressure causes resistant individuals to mutate in order to survive

48
Q

antibiotic resistance: non resistant individuals…

A

died as there was a compettion for survival/survival of the fittest

49
Q

antibiotic resistance: resistant individuals…

A

reproduce passing allele for resistance onto offspring, so overtime the number of resistant individuals in a population increases as the allele becomes more frequent.

50
Q

histogram vs bar chart

A

histogram does not have gaps between the bars, so grouping makes it easier to see patterns, the data is also continuous

51
Q

What is meant by the term “pharmacogenomics”?

A

The study of how a person’s genes affect their response to particular drugs.

52
Q

what is the founder effect

A

the loss of genetic variation that occurs when a new population (colony) is established by a very small subset of individuals from a larger population

53
Q

the founder effect plays a role in the

A

emergence of new species

54
Q

how do the genetics differ between the founder population and the original population

A

the genetics of the founder population reflects that of its initial members not the original source population

55
Q

what are homologous structures

A

a similar anatomical structure but not superficial
inherited from a common ancestor
doing dissimilar functions

56
Q

what are analogous structures

A

similar superficial structure to perform the same role but anatomical structure is very diffferen

57
Q

analogous structure eg

A

aquatics forelimbs shark, penguin, dolphin

58
Q

homologous structure eg

A

pentadactyl limb

59
Q

what type of evolution is linked to homologous structures\

A

DIVERGENT

60
Q

what type of evolution is linked to analogous structures

A

ANALOGOUS

61
Q
A

alevel biology ocr (20 decks)

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