1.7 Evolution Flashcards

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1
Q

Define ‘Evolution’

A

Evolution is the gradual changes in organisms over generations as a result of genomic variations.

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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 is an advantage of horizontal gene transfer?

A

Allows for rapid evolutionary change

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5
Q

Describe the process of transformation horizontal gene transfer

A

Bacteria takes up naked bacteria from foreign cell

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6
Q

Define ‘Natural Selection’

A

Non random increase in the frequency of DNA sequences that increase survival chance of organism and the non-random decrease in deleterious sequences.

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7
Q

What is a deleterious sequence?

A

A deleterious sequence is a gene sequence that decreases the organism’s chance of survival

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8
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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9
Q

Describe the process of natural selection

A

1 - Mutations change genotypes which changes phenotypes
2 - Selection pressures acts on phenotypes
3 - Phenotypes with selective advantage survive and reproduce which increase in frequency of advantageous mutations with successive generations
4 - Phenotypes with reduced advantage become extinct

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10
Q

What are the three types of selection pressures?

A
  • Stabilising
  • Disruptive
  • Directional
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11
Q

What selection pressure is baby weight an example of?

A

Stabilising

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12
Q

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

A

Disruptive

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13
Q

Describe Directional selection pressure

A
  • favours one extreme
  • shifts graph to left or right
  • example: peppered moths
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14
Q

A species is a group of organisms capable of …

A

A species is a group of organisms capable of interbreeding and producing fertile offspring, and which does not normally breed with other groups

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15
Q

What is ‘Speciation’

A

The formation of a new species

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16
Q

Why must populations be separated for speciation to occur?

A

So interbreeding is prevented to have no gene flow.

17
Q

What are the three main steps in speciation?

A
  • Isolation
  • Mutation
  • Natural Selection
18
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

19
Q

What are the two types of isolation barriers?

A

Geographical

Behavioural/Ecological

20
Q

What type of isolation barrier does sympatric selection need?

A

Behavioural/Ecological

21
Q

Describe Allopatric Selection

A

Formation of new species with a geographical barrier separating them

22
Q

How can scientists prove new species have been formed?

A

If two members of the populations breed and produce infertile offspring