1.7 evolution

Question 1

Define evolution

Answer 1

The gradual change in organisms over generations

Question 2

Define natural selection

Answer 2

The non-random increase in the occurrence of sequences of DNA that would increase survival
Or
The non-random decrease in the occurence of the deleterious sequence (DNA sequences that would cause harm to the organism)

Question 3

Define vertical gene transfer

Answer 3

Genes are passed from generation to generation

Question 4

Define horizontal gene transfer

Answer 4

Genes are passed between different individuals of the same generation

Question 5

Define sexual reproduction

Answer 5

Different combination of genes are combined from 2 parents resulting in genetic variation

Question 6

Define asexual reproduction

Answer 6

One parent transfers its genes to their offspring resulting in them being genetically identical

Question 7

Define speciation

Answer 7

The process where a new species is produced through evolution

Question 8

Define species

Answer 8

A group of organisms that have the ability to interbreed and produce fertile offspring

Question 9

Define allopatric

Answer 9

Result of a physical barrier (geographical)

Question 10

Define sympatric

Answer 10

Result of a barrier that does not physically separate a species (ecological or behavioural)

Question 11

Why does evolution take place

Answer 11

Evolution allows a species to become better adapted to certain conditions

Question 12

Identify 2 selection pressures

Answer 12

• increased competition

- new predator

Question 13

Give an example of natural selection

Answer 13

Peppered moths

Light form > industrial revolution > dark form

Question 14

Identify the 3 forms of natural selection

Answer 14

• disruptive
• directional
• stabilising

Question 15

Explain stabilising

Answer 15

When more common phenotypes are favoured and phenotypes at either extreme are removed from the gene pool

Question 16

Explain disruptive selection

Answer 16

When phenotypes at both extremes are favoured and remain in the gene pool

Question 17

Explain directional selection

Answer 17

The phenotypes at one extreme are favoured and remain in the gene pool and the other extreme is removed

Question 18

Explain the 4 stages of speciation

Answer 18

Isolation - caused by a type of barrier
Mutation - once a barrier has formed mutations will occur within the 2 different groups
Natural selection - organisms are exposed to selection pressures and those with the advantageous mutations will survive
New species - following natural selection the new group of organisms will feature the stronger genes, if the barrier is removed the 2 new sub populations will no longer be able to interbreed and produce and fertile offspring

Question 19

Give an example of each barrier

Answer 19

• (Geographical) mountain range/river
• (behavioural) mailing dance/song
• (ecological) pH/temperature