Natural Selection

Question 1

Phenotype

Answer 1

The observable characteristics of an organism resulting from its genotype and interactions with the environment

Question 2

Gene

Answer 2

A length of DNA which codes for a protein or polypeptide

Question 3

Genotype

Answer 3

The genetic constitution of an organism

Question 4

Homozygous

Answer 4

Two alleles of gene of the same

Question 5

Heterozygous

Answer 5

The two alleles of a gene different

Question 6

Allele

Answer 6

Different farms of a gene

Question 7

Recessive

Answer 7

The allele which is only expressed in the females hype in absence of a dominant allele

Question 8

Dominant

Answer 8

The angle is always expressed in the phenotype, even if a different alley/heterozygous for the same genius present

Question 9

Loki

Answer 9

The position of a gene on a chromosome

Question 10

Genetic diversity

Answer 10

The number of different alleys of the same gene

Question 11

Allele frequency

Answer 11

The number of different times an allele appears in a population

Question 12

Gene pool

Answer 12

Total number of alleles in a particular population

Question 13

What two factors cause variation?

Answer 13

Genetic factors
Environmental changes

Question 14

The process of natural selection

Answer 14

New allele arises due to random mutation
Leads to variation in a population
Population may be geographically isolated so no interbreeding
Different selection pressures
Competition for resources-intraspecific competition
New alleys give a selective advantage so organism survive and reproduces
Pass on advantageous all to next generation
Frequency of all oil in population increase increases
Frequency of phenotype increases

Question 15

3 main selection pressures

Answer 15

Predation
Disease
Competition

Question 16

Stabilising selection

Answer 16

Organisms with phenotypes in the middle are more favourable than the two extremes of a population usually when selection pressure stay constant

Question 17

directional selection

Answer 17

Organisms with phenotype are one extreme more favourable within a population usually when a selection pressure changes

Question 18

Disruptive selection

Answer 18

Organisms with phenotype but both extremes are more favourable within a population usually when selection pressure change leading to speciation

Question 19

Antibiotic resistance

Answer 19

Link natural selection Mark scheme to white antibiotics no longer impact said and strains of bacteria

Question 20

Allopatric speciation

Answer 20

Variation in the population due to mutation
Two group groups become geographically isolated so reproductively isolated
No gene flow/gene pool remains constant
Each group experiences different selection pressures
Different alleles pass on/change in frequency of alleles
Two parts of the population cannot breathe to produce fertile offspring and becomes separate species

Question 21

Sympatric speciation

Answer 21

Variation in the population due to mutation
The two groups are not geographically isolated
But they are reproductively isolated
No gene flow/gene pool remains separate
Change in frequency of alleles
Two parts of the population cannot breed to produce fertile offspring and becomes separate species

Question 22

Genetic drift

Answer 22

The change in allele frequency due purely to chance events and not selection pressures