Selection And Evolution

Question 1

Biological variation

Answer 1

There are some individuals better suited/ adapted to their environment increasing their chances of surging to reproduce

Question 2

Evolution

Answer 2

The process of change by natural selection leading to speciation

Question 3

Natural selection

Answer 3

The mechanism that’s brings about the evolution of new species

• survival of the fittest
• can lead to isolated groups within a population, so much that they can become a second species

Question 4

Stabilising selection

Answer 4

When organisms are well adapted to their environment and it’s is one that does not change, natural selection works against new phenotypes and acts in favour of the average phenotype

Question 5

Directional selection

Answer 5

If organisms are well adapted to an environment but it changes, natural selection favour a new phenotype or one at the end of the phenotypic range

Question 6

Disruptive selection

Answer 6

When there is more than one type of habitat within an area and the extremes of the phenotypes are favoured over the intermediates

Question 7

Genetic drift

Answer 7

When allele frequencies can change by a random process

• only important in small populations
• it happens by random probability

Question 8

Hardy-Weinberg principle

Answer 8

States that in a diploid, sexually reproducing organism, allele and genotype frequnecies remain constant from generation to generation if Bettina conditions are met:

• population is large
• matings are random
• there are no net mutations
• no migration in or out of population
• no selection for or against an allele

Question 9

Speciation

Answer 9

The formation of a new species from an existing one-must have evolved to be reproductively isolated from one another

Question 10

Barriers which have evolved that being out reproductive isolation

Answer 10

• Prezygotic mechanism prevent a zygote being formed
• postzyotic mechanisms prevent hybrids from passing on their genes (offspring may not be produces or if they are the have reduced fitness)

Question 11

Allopathic speciation

Answer 11

Speciation resulting from geographical separations of populations
E.g. Darwins finches on the Galapagos

Question 12

Sympatric speciation

Answer 12

When two or more species are formed from a single ancestor, each occupying the same geographical location. This often happens through polyploidy

Question 13

Polyploidy

Answer 13

Polyploids are organisms with more than two compete sets of chromosomes in their cells. (Rarely animals usually plants). Polyploidy results from problems during meiosis, like if the pairs of homologous chromosomes fail to separate creating a tetraploid not a diploid

Question 14

T-test

Answer 14

Used to find if there is a significant difference between two different groups- must have a probability level of 5% we can accept the groups are close, if not it is a null hypothesis and we reject it