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CfE Higher Biology > 1.7 Evolution > Flashcards

1.7 Evolution Flashcards

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1
Q

Define ‘Evolution’

A

Evolution is the gradual change in the characteristics of an organism over many generations

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2
Q

What is the difference between vertical and horizontal inheritance?

A

Vertical- passing of genetic material from parent to offspring
Horizontal- passing of genetic material across the same generation by transfer of plasmid between adjacent cells

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3
Q

Give an example of an organism that can transfer genetic material through vertical or horizontal inheritance

A

Prokaryotes

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4
Q

What are the three types of horizontal gene transfer?

A 
<ul>
<li>Conjunction</li> 
<li>Transformation</li>
<li>Transduction</li>
</ul>
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5
Q

What is an advantage of horizontal gene transfer?

A

Allows for rapid evolutionary change

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6
Q

Describe the process of transformation horizontal gene transfer

A

Bacteria takes up naked bacteria from foreign cell

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7
Q

Describe the process of conjunction horizontal gene transfer

A
  • A conjunction bridge is formed between two adjacent cells allowing a plasmid to be copied and travel through the bridge to the adjacent cell
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8
Q

Describe the process of transduction horizontal gene transfer

A

Phage inserts the viral DNA into the cell

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9
Q

Define ‘Natural Selection’

A

Non random increase in the frequency of DNA sequences that increase survival chance of organism

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10
Q

What is a deleterious sequence?

A

A deleterious sequence is a gene sequence that decreases the organism’s fitness

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11
Q

How are deleterious sequences removed by natural selection?

A

Decrease the organism’s survival rate and so are selected against, meaning their frequency will decrease

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12
Q

Define ‘Sexual Selection’

A

Non random increase in the frequency of DNA sequences that increase reproductive success of organism

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13
Q

What are the three types of selection pressures?

A

Stabilising
Disruptive
Directional

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14
Q

What selection pressure is baby weight an example of?

A

Stabilising

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15
Q

What type of selection pressure favours the two extremes and is the driving force between sympatric selection?

A

Disruptive

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16
Q

Describe Directional selection pressure

A
  • favours one extreme
  • shifts graph to left or right
  • example: peppered moths
17
Q

What is the main difference between natural selection and genetic drift?

A

Natural Selection is non random, Genetic Drift is random

18
Q

Define ‘Genetic Drift’

A

RANDOM increase/decrease in the frequency of a DNA sequence in the gene pool of a population

19
Q

What are the mechanisms for Genetic drift

A
  • Chance Events
  • Neutral Mutations
  • Founder Effect
20
Q

What is the founder effect?

A

The founder effect is where a small population becomes isolated and that small population has a gene pool that does not reflect the original population
Mechanism of Genetic Drift

21
Q

What is the Bottleneck effect?

A

This is where the majority of the population die out in a chance event(such as natural disaster) and the gene pool of the survivors does not reflect the original gene pool
Mechanism of Genetic Drift

22
Q

What is ‘Speciation’

A

The formation of a new species

23
Q

Why must populations be separated for speciation to occur?

A

So interbreeding is prevented

24
Q

Explain why genetic drift is more evident in smaller populations

A

Smaller populations so will have a bigger effect due to smaller gene pool

25
Q

What are the three main steps in speciation?

A

Isolation
Mutation
Natural Selection

26
Q

Describe what happens in the natural selection stage of speciation

A

Mutations may confer an advantage in habitat of population and so the the mutation will be selected for and will increase in frequency

27
Q

What are the two types of isolation barriers?

A

Geographical

Behavioural/Ecological

28
Q

What type of isolation barrier does sympatric selection need?

A

Behavioural/Ecological

29
Q

Describe Allopatric Selection

A

Formation of new species with a geographical barrier separating them

30
Q

How can scientists prove new species have been formed?

A

If two members of the populations breed and produce infertile offspring

31
Q

What is a hybrid zone?

A

A hybrid zone is an area of interbreeding between two closely related species

32
Q

What does a narrow hybrid zone represent?

A

Genetically distinct populations

33
Q

What would the width of the hybrid zone be if the populations were genetically

A

M

CfE Higher Biology (26 decks)

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