3.7.3- Evolution may lead to speciation

Question 1

What is evolution?

Answer 1

Process by which organisms become better adapted to suit their environment

Question 2

What is variation?

Answer 2

Measure of difference between individuals (phenotype)

Question 3

What is allele frequency ?

Answer 3

How often an allele appears in a population

Question 4

What is speciation?

Answer 4

Formation of new species

Question 5

What is the major cause of variation?

Answer 5

Random mutation

Question 6

What are phenotypic changes caused by?

Answer 6

Changes in the genome

Question 7

What are the sources of variation?

Answer 7

Random mutation
Meiosis
Phenotype changes
Random fertilisation

Question 8

When is an allele most likely to be inherited ?

Answer 8

When it offers an organisms an advantage

Question 9

What does an allele being inherited lead to?

Answer 9

Increase in allele frequency = natural selection

Question 10

What are selection pressures ?

Answer 10

The changes that can cause/ force an entire population to adopt a new phenotype

Question 11

What are the 3 main selection pressures?

Answer 11

Disease
competition
predation

Question 12

What are the 3 types of selection?

Answer 12

Directional
Stabilising
Disruptive

Question 13

What is a gene pool?

Answer 13

Total number of all the alleles of all the genes in all individuals within a population at a given time

Question 14

What is directional selection?

Answer 14

Environmental selection pressures favour individuals that are different in one direction, to the mean

Question 15

What is disruptive selection?

Answer 15

Selection pressures favour individuals with the more extreme phenotypes

Question 16

What is stabilising selection?

Answer 16

Environmental selection pressures favour individuals that represent the mean. This will preserve the current population + extreme phenotypes are not beneficial

Question 17

Define Allopatric speciation?

Answer 17

Species can form when they become geographically isolated, leading to different environments

Question 18

Define sympatric speciation?

Answer 18

Does not require geographical isolation

Question 19

Explain sympatric speciation?

Answer 19

Individuals in a species gain a characteristic (due to a mutation) that allows them to exploit a niche in the environment
The other individuals in the population, without the mutation still continue to thrive

Question 20

What is artificial selection ?

Answer 20

Individuals are forced to breed due to humans choosing desire characteristics to be bred

Question 21

Where does genetic drift occur ?

Answer 21

In small populations

Question 22

Explain genetic drift

Answer 22

If an individual happens to die without reproducing then their alleles are lost from the gene pool.

Conversely, if a no. of individuals reproduce more than would be expected, then the alleles they carry would flood the gene pool

Question 23

What is a genetic drift from the norm?

Answer 23

The result of the gains + losses of alleles can cause a change in the allele frequencies in the entire population.