Evolution 1.7

Question 1

Evolution definition

Answer 1

The gradual change in species over generations, resulting in genomic variation.

Question 2

What is evolution caused by

Answer 2

Natural selection

Question 3

Why does evolution occur

Answer 3

To allow a species to become better adapted to their environment.

Question 4

Natural selection definition

Answer 4

The non random increase in occurrence of advantageous sequences of DNA which would increase the chance of survival and reproducing, and a non random decrease in the occurrence of deleterious DNA sequences, which are the DNA sequences that would cause harm in an organism.

Question 5

Selection pressures definition

Answer 5

The factors resulting in natural selection.

Question 6

Selection pressure examples

Answer 6

Increased competition
Changes in environment
Introduction of new diseases
Introduction of new predators

Question 7

Types of natural selection

Answer 7

Stabilising
Directional
Disruptive

Question 8

Stabilising natural selection definition

Answer 8

Where organisms with phenotypes at both extremes are not favoured and removed from the gene pool and the more common phenotype is favoured and remains in the gene pool

Question 9

Directional selection

Answer 9

Where organisms with phenotypes of one extreme is favoured and remain in the gene pool, with the other phenotypes being removed from the gene pool

Question 10

Directional selection results

Answer 10

Results in mean phenotype will shift left or right (towards an extreme)and the variation decreases.

Question 11

Stabilising selection result

Answer 11

the mean phenotype stays the same but the variation decreases .

Question 12

Disruptive selection

Answer 12

Where those with phenotypes at both extremes are favoured and remain in the gene pool, but the common phenotype is removed due to not being favoured.

Question 13

Result of disruptive selection

Answer 13

There are now two new and separate mean phenotypes and variation decreases.

Question 14

Phenotype definition

Answer 14

The physical traits that an organism expresses.

Question 15

Gene transfer two methods

Answer 15

Horizontal and vertical

Question 16

Horizontal gene transfer definition

Answer 16

Where genes are passed between different individuals of the same generation.

Question 17

Horizontal gene transfer occurs in

Answer 17

Prokaryotes

Question 18

What type of gene transfer is the fastest

Answer 18

Horizontal gene transfer

Question 19

What type of gene transfer is the slowest

Answer 19

Vertical gene transfer

Question 20

Vertical gene transfer definition

Answer 20

Where genes are passed between organisms of different generations in sexual or asexual reproduction.

Question 21

Where does vertical gene transfer occur

Answer 21

In eukaryotes

Question 22

Vertical gene transfer in sexual organisms

Answer 22

Parents will reproduce with each other, the offspring receive one set of chromosomes from each parent, which increases variation.

Question 23

Vertical gene transfer in asexual organisms

Answer 23

Where parent organisms reproduce on their own producing genetically identical organisms and decreasing variation.

Question 24

Species definition

Answer 24

A group of organisms which can interbreed to reproduce fertile offspring.

Question 25

Speciation definition

Answer 25

The process where a new species is formed through evolution, involving isolation, mutation, adaptation and natural selection, and these organisms no longer being able to reproduce with each other.

Question 26

Types of isolation barriers

Answer 26

Geographical
Behavioural
Ecological

Question 27

Geographical isolation barriers

Answer 27

An isolation barrier which splits up a population, by stopping organisms interbreeding with each other, through physical landmarks.

Question 28

Ecological isolation barriers

Answer 28

Isolation barriers where a population is split up, stopping organisms from interbreeding, through change in abiotic factors

Question 29

Behavioural isolation barriers

Answer 29

An isolation barrier which splits up a population, stopping them from interbreeding with each other, through differences in how the organisms act.

Question 30

Stages of speciation

Answer 30

Isolation
mutation
adaptation and natural selection
new species is formed.

Question 31

Isolation definition in speciation

Answer 31

Where an isolation barrier forms between a population dividing the population and preventing gene flow.

Question 32

Mutation in speciation

Answer 32

A random and spontaneous change in an organisms genes will occur in the divided populations resulting in new alleles being introduced into these species.

Question 33

Adaptation and natural selection in speciation

Answer 33

Organisms are exposed to selection pressures, which allows organisms with advantageous mutations to reproduce and pass on their genes and organisms with disadvantageous genes to be removed from the gene pool.

Question 34

Types of speciation

Answer 34

Allopatric and sympatric

Question 35

Allopatric speciation

Answer 35

Speciation which occurs when the isolation barrier is geographical

Question 36

Sympatric speciation

Answer 36

Where speciation occurs due to an ecological or behavioural isolation barrier.

Question 37

Difference between Allopatric and sympatric speciation

Answer 37

Allopatric speciation is brought about by a geographical barrier, whereas sympatric is brought about by an ecological or behavioural barrier.
Allopatric speciation occurs when organisms are physically separated, whereas sympatric occurs when organisms are isolated in the same area without physical separation.
Allopatric produces new species slowly due to natural barriers needing to form and species to be reintroduced to each other, whereas sympatric produces new species quickly.