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3/4 Biology > Variation In Generations/ Evolution > Flashcards

Variation In Generations/ Evolution Flashcards

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1
Q

How can gene flow alter allele frequencies?

A

Genes can be exchanged with other gene pools as individuals move between them

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2
Q

How can natural selection alter allele frequencies?

A

Selection pressures against certain allele combinations may reduce reproductive success

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3
Q

How can mutations alter allele frequency?

A

Spontaneous mutations can alter frequencies and create new alleles

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4
Q

How can small population size and genetic drift alter allele frequencies?

A

In small populations allele frequencies can change randomly from generation to generation, alleles may be lost or fixed

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5
Q

How can non random mating alter allele frequencies?

A

Individuals seek out a particular phenotype with which to mate

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6
Q

What is a directional process that alters allele frequency?

A

Some particular alleles are favoured over others

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7
Q

What is genetic drift?

A

A mechanism of evolution in which allele frequency within a population changes over generations due to chance

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8
Q

What type of population is genetic drift strongest in?

A

Small populations

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9
Q

Mechanisms of genetic drift include:

A
  • natural selection
  • gene flow
  • mutation
  • bottle neck and founder effects
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10
Q

What could cause a rapid change in allele frequencies within a small population?

A

A major event eg. disease

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11
Q

What is gene flow?

A

The movement of genes in or out of a population (immigration or emigration)

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12
Q

What does gene flow result in between different populations?

A

Reduces differences between populations because the gene pools become more similar

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13
Q

What is another name for random mating?

A

Non assortive mating

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14
Q

When individuals search out mates that are most like themselves this is known as?

A

Assortive mating

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15
Q

What must occur for natural selection and evolution to occur?

A
  • there is phenotypical variation
  • some individuals have a favoured phenotype which improves chances of survival and reproduction
  • over time there is a greater chance of favoured phenotype offspring being born
  • the favoured phenotype will increase if selective pressures don’t change
  • in time a new species may evolve
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16
Q

What are some ways variation can be caused?

A
  • sexual reproduction
  • mutation
  • gene flow
  • environmental factors
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17
Q

How can mutations occur?

A
  • point/ base
  • block
  • whole chromosomes
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18
Q

What term is given to mutations that are neither harmful or beneficial?

A

Neutral or silent

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19
Q

Why are neutral mutations hard to detect?

A

Because they have little or no change in the phenotype

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20
Q

Why may neutral mutations be important in an evolutionary sense?

A

Even though they have no adaptive value when it occurs this may not be the case in the future

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21
Q

In what ways do block mutations occur?

A
  • as a result of errors during crossing over in meiosis

- mutagens can also cause block mutations

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22
Q

What ways can block mutations be described?

A
  • inversion
  • translocation
  • duplication
  • deletion
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23
Q

What is an inversion block mutation?

A

Pieces of chromosome are flipped so their genes appear in the reverse order

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24
Q

What is a translocation block mutation?

A

Pieces of chromosome are moved from one chromosome to another

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25
Q

What is a duplication block mutation?

A

Pieces of chromosome are repeated so there are duplicated sequences

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26
Q

What is a deletion block mutation?

A

Pieces of chromosome are lost

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27
Q

How do whole chromosome mutations occur?

A

Occurs due to whole chromosomes being misplaced. Usually due to a mistake in cell division.

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28
Q

A mistake in meiosis is known as?

A

Non-disjunction

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29
Q

What are the two forms of non-disjunction mutations?

A
  • aneuploidy

- polyploidy

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30
Q

What is aneuploidy?

A

A condition where one or more chromosomes are missing from or added to the normal somatic cell chromosome number

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31
Q

What is polyploidy mutations?

A

Polyploidy describes the state of having 3 or more complete sets of chromosomes

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32
Q

How many of each chromosome is present due to polyploidy mutations?

A

3 or more of EVERY one

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33
Q

Is polyploidy often observed in human?

A

It is rarely observed and is thought to be a common cause of spontaneous abortion

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34
Q

Gene mutations involving a single usually called?

A

Point mutations

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35
Q

What is the result of the bottleneck effect?

A

Only a small number of individuals remain in the gene pool to contribute their genes to the next generation

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36
Q

What can cause a bottleneck effect?

A
  • seasonal climate change
  • heavy predation or disease
  • catastrophic event eg. Flood
37
Q

What does extinction mean?

A

A species no longer exists and the alleles for the species have been eradicated

38
Q

How can the actions of humans cause extinction?

A
  • causing climate change
  • introduction of feral organisms
  • exploitation
  • removing habitats
39
Q

The term gene pool refers to the

A

Genetic makeup of a population

40
Q

All the alleles within a population are referred to as …

A

The gene pool

41
Q

New alleles arise in a sexually reproducing population by…

A

Mutations in DNA sequence prior to meiosis

42
Q

Hominids are believed to have evolved in Africa because?

A

The oldest hominid fossils have been found in Africa

43
Q

Why would selective breeding over many generations has produced gradual changes in farm animals?

A

from the restriction of breeding to chosen animals within the herd

44
Q

Convergent evolution is?

A

Responsible for the development of analogous structures

45
Q

Another name for divergent evolution is?

A

adaptive radiation

46
Q

The measurement of the rate of accumulation of random genetic changes in the genomes of chimpanzees and humans is called?

A

a molecular clock

47
Q

What is meant by the term ‘novel phenotype’?

A

a new phenotype due to a repeated gene or a change in gene expression

48
Q

Any rise in incidence of antibiotic-resistant bacteria is due to?

A

antibiotic-resistant phenotypes being favoured through natural selection.

49
Q

How is mitochondrial DNA inherited?

A

From the female parent

50
Q

The order of first appearance of various human species, from oldest to most recent, has been shown to be?

A

Homo habilis, Homo erectus and Homo sapiens.

51
Q

What does biological evolution involve?

A

Involves inherited change in a population over many generations

52
Q

Two species are closely related by evolutionary descent. It may be predicted that members of these species would show the presence of?

A

Homologous structures

53
Q

Evidence that the earliest hominins could walk erect comes from studies of their fossils. Confirmation that they walked erect came from examining?

A

The position of the foramen magnum on the under surface of the skull

54
Q

What dating method is used for fossils less than 200,000 years?

A

Thermoluminescence

55
Q

What dating method is used for fossils less than 350,000 years?

A

Uranium/ thorium

56
Q

What dating method is used for fossils +- 50,000 years?

A

Carbon 14

57
Q

What dating method is used for fossils 100-10,000million years?

A

Potassium/ argon

58
Q

How many years does it take for carbon 14 to change to nitrogen?

A

5,730 years

59
Q

The changing of carbon 14 to nitrogen is known as an isotopic…

A

Half life

60
Q

Where are fossils commonly found?

A

Sedimentary rock, amber, tar, ice or peat bogs

61
Q

What is micro evolution?

A

Describes the small scale changes within a gene pool over generations

62
Q

What is macro evolution?

A

Is the term used to describe large scale changes in form, as viewed in the fossil record, involving whole species

63
Q

What is phylogeny?

A

The evolutionary history of a species or toxonomic group

64
Q

What is evolution

A

Permanent genetic change in a population of individuals

65
Q

Putting fossils in an order of time is called?

A

Geological time scale

66
Q

What is it called when structures have the same function in different organisms but they also come from a different origin?

A

Analogy

67
Q

What can analogic structures indicate?

A

Convergence

68
Q

What are vestigal structures?

A

Some transitional fossils have evidence of reminders of bone structures that are no longer used

69
Q

What is an example of a vestigal structure?

A

The reduced hip and leg bone in a whale

70
Q

What is a good way to reconstruct the evolutionary history of a species?

A

DNA hybridisation

71
Q

How does the process of DNA hybridisation occur?

A

DNA from different species is unzipped and recombined to form hybrid DNA.

72
Q

What is used to seperate hybrid DNA after DNA hybridisation?

A

Heat can be used and the amount of heat required to do this is a measure of how similar the two DNA strands are

73
Q

How come some DNA hybrids are harder to seperate than others?

A

The greater the similarity of base sequence between the two strands the harder it is to seperate

74
Q

How are amino acid sequences determined?

A

By inherited genes and differences are due to mutations

75
Q

What does the distribution of species over the world indicate?

A

That modern forms evolved from ancestral populations and spread (radiated) out into new environments

76
Q

What are the two types of evolution?

A

Divergent, convergent

77
Q

What form evolution is the classic version?

A

Divergent

78
Q

What is the process of divergent evolution?

A

An interbreeding population or species seperate into two or more descendant species resulting in once similar or related species becoming more dissimilar

79
Q

What is a source of divergent evolution?

A

Allopatric speciation is a source of divergent evolution by creating barriers and reducing gene flow

80
Q

What is a phylogeny tree?

A

Diagrams that show evolutionary pathways of species.

81
Q

What is convergent evolution?

A

The occurrence of similar characteristics that have occurred in species that ave no shared DNA ie. no common ancestor

82
Q

Why do similar features occur in two organisms with no common ancestor?

A

This is due to organisms being subjected to similar selection pressures.

83
Q

Which combination of structural features is common to most early vertebrate embryos?

A

Gill slits, yolk sacs

84
Q

The main conclusion that can be drawn from comparative embryology is that?

A

common structures in embryos of dissimilar species reveal common ancestry.

85
Q

When compared to other apes, human have larger?

A

Brains relative to skull size

86
Q

The founder effect and bottleneck are examples of?

A

Genetic drift

87
Q

The out-of-Africa hypothesis proposes?

A

that Homo erectus evolved into Homo sapiens in Africa before migrating to other continents

88
Q

How is allopatric speciation characterised?

A

A geographic isolating mechanism preventing gene flow

89
Q

Hominins and primates both share?

A

Opposable thumbs

3/4 Biology (7 decks)

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