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OCR A level biology > Variation and Evolution > Flashcards

Variation and Evolution Flashcards

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1
Q

Give 4 sources of evidence for evolution

A
  • Palaeontology (fossils)
  • comparative anatomy
  • comparative biochemistry
  • comparative embryology
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2
Q

How can the relative age of fossils be determined?

A
  • over time sediment is deposited to form rock strata
  • recent rock strata are found at the top and older rock strata are found at the bottom
  • radioisotope dating can be completed on fossils to date rock strata
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3
Q

How do fossils provide evidence for evolution?

A
  • fossils of the simplest organisms are found in the oldest rocks
  • fossils of more complex organisms are found in more recent rocks
  • allow relationships between extinct and living organisms to be investigated
  • sequence in which organisms are found matches ecological links
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4
Q

What is comparative anatomy?

A

The study of similarities and differences between organisms’ anatomy

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5
Q

How does comparative anatomy provide evidence for evolution?

A

-Homologous structures provide evidence for divergent evolution and that from a common ancestor different species have evolved

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6
Q

What are homologous structures?

A

A structure which appears superficially different (and may perform different functions) in different organisms but has the same underlying structure

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7
Q

What is divergent evolution?

A

Species diverge over time into two different species, resulting in new species becoming less like the old one

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8
Q

What is comparative biochemistry?

A

Similarities and differences between the chemical make up of organisms

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9
Q

How does comparative biochemistry provide evidence for evolution?

A
  • molecules change over time
  • some important molecules are highly conserved among species
  • slight changes that do occur in these molecules can help identify evolutionary links
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10
Q

How does comparative embryology provide evidence for evolution?

A
  • embryos of different animals looks very similar
  • shows animals develop in a similar way
  • implies the process of embryonic development has a common origin
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11
Q

What is variation?

A

Differences in characteristics or genes within or between species

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12
Q

Define intraspecific variation

A

Differences between individuals within the same species

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13
Q

Define interspecific variation

A

Differences between different species

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14
Q

What are the 2 causes of variation?

A

Environment and genetics

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15
Q

Are environmental effects heritable?

A

No

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16
Q

Give 2 examples of environmental effects

A

Hair dye

Diet

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17
Q

Are genetic factors heritable?

A

Yes

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18
Q

What are the 5 causes of genetic variation?

A
  • presence of a different allele
  • random fertilisation/random fusion of gametes
  • random mating
  • meiosis
  • mutations
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19
Q

What are the two types of mutations?

A

Point mutations and chromosomal mutations

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20
Q

What are point mutations?

A

Change in the base sequence of DNA

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21
Q

How do chromosomal mutations arise?

A

From crossing over

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22
Q

What are the two sources of variation in meiosis?

A
  • crossing over

- independent assortment

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23
Q

What are the two types of variation?

A

Continuous and discontinuous

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24
Q

What is continuous variation?

A
  • Variation of all possible intermediate values between the two extremes
  • it can be plotted to give a normal distribution curve
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25
Q

Give 2 examples of continuous variation

A

Height

Weight

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26
Q

What is discontinuous variation?

A
  • discrete groupings of individuals

- presented as a bar chart

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27
Q

Give an example of discontinuous variation

A

Blood group

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28
Q

Why does continuous variation occur?

A

-due to the inheritance of 2 or more genes

29
Q

Why does discontinuous variation occur?

A

Result of inheritance of one gene with 2 or more alleles

30
Q

Is continuous variation influenced by the environment?

A

It can be

31
Q

Is discontinuous variation influenced by the environment?

A

No

32
Q

Define polygenic

A

A characteristic is controlled by two or more genes

33
Q

Define multifactorial

A

Involving both genetic and environmental factors

34
Q

Outline the process of natural selection

A
  • populations show a wide range of variation
  • population is exposed to a selection pressure
  • organisms with a characteristic enables them to survive the selection pressure have an advantage
  • they survive and reproduce
  • organisms that survive possess an allele giving them the advantageous characteristic
  • offspring gain the survival advantage
  • frequency of the advantageous allele increases
35
Q

What are the 4 characteristics of a normal distribution curve?

A
  • unimodal
  • asymptotic
  • symmetrical
  • mean, median, and mode are all equal
36
Q

What is standard deviation?

A

A measure of spread of data around the mean

37
Q

What is the student’s t test used for?

A

To compare 2 sets of numerical data

38
Q

When is the unpaired t test used?

A

To compare data from different individuals

39
Q

When is the paired t test used?

A

To compare data from the same individual

40
Q

When is Spearman’s rank correlation coefficient used?

A

To determine if there is a correlation between two variables

41
Q

Define adaptation

A

Characteristics that increase an organism’s chance of survival and reproduction in its environment

42
Q

What are the 3 types of adaptations?

A
  • anatomical
  • behavioural
  • physiological
43
Q

What are anatomical adaptations?

A

Adaptations relating to physical features, both internal and external

44
Q

Give 4 examples of anatomical adaptions

A
  • Camouflage
  • Teeth i.e. shape and type are related to diet
  • Mimicry
  • Body Covering i.e. scales, feathers, fur
45
Q

What are behavioural adaptations?

A

Adaptations relating to the way an organism acts

46
Q

What are the 2 types of behavioural adaptations?

A

Innate and learned

47
Q

What is an innate behavioural adaption?

A

The ability to do the behaviour is inherited through genes

48
Q

Give an example of 2 innate adaptions

A
  • spiders building webs

- caterpillars building cocoons

49
Q

What is a learned behaviour adaptation?

A

a behaviour that is learnt from experience or observation

50
Q

Give 2 examples of learned adatations

A
  • use of tools

- playing dead

51
Q

What are physiological adaptations?

A

Adaptations relating to processes that take place within an organism

52
Q

Give 4 examples of physiological adaptations

A
  • Poison production in reptiles and plants
  • Antibiotic production to kill competing bacteria
  • water holding better adapted for dry conditions
  • blinking
53
Q

Define analogous structure

A

Structures which have adapted to perform the same function but have different (genetic) origins

54
Q

Define convergent evolution

A

Organisms evolve similarities because the organisms adapt to similar environments or other selection processes

55
Q

Why do organisms from different taxonomic groups show similar structures?

A

-they adapt to similar environments or other selection pressures

56
Q

Give an example of two sets of organisms from different taxonomic groups that are similar

A

Marsupials and placental mammals in Australia

57
Q

Define allele frequency

A

How many alleles of a particular type are found in the total number of possible alleles for that gene

58
Q

Define gene pool

A

All genes and their allelic forms in a given population

59
Q

Define selection pressure

A

Any factor for which there is competition between individuals in which some will survive and some will die

60
Q

Define selectively neutral gene

A

an allele not involved in the selection of individuals

61
Q

Define advantageous allele

A

An allele which provides an individual with a survival advantage

62
Q

Define advantageous characterisitc

A

A characteristic which arises from an advantageous allele, which provides an individual with a survival advantage

63
Q

Define evolution

A

The process by which different kinds of living organisms are believed to have developed from earlier forms during the history of the earth

64
Q

Define natural selection

A

The process by which organisms best suited to their environment survive and reproduce, passing on their characteristics to their offspring through their genes

65
Q

Describe the effect of the industrial revolution on peppered moths

A
  • before the industrial revolution peppered moths were light in colour
  • after the industrial revolution peppered moths became darker
  • soot caused the bark of trees to get darker
  • dark colour moths were better camouflaged
  • light moths were eaten
66
Q

What was the effect of the industrial revolution on the allele frequency for black wings in peppered moths?

A

The alleles frequency increased

67
Q

What characteristics increase the ability of a population to survive a change in the environment?

A
  • having a large gene pool means a population is likely to evolve and tolerate change in environment
  • because the population is more likely to have some individuals with advantageous characteristics who will survive
68
Q

Give 3 organisms which human activity has affected the populations

A
  • blowflies
  • MRSA
  • flavobacterium
69
Q

How have humans affected Staph. A?

A

-use of antibiotics has led to bacteria developing resistance

OCR A level biology (44 decks)

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