20 Patterns of Inheritance

Question 1

What is the gene pool?

Answer 1

The total sum of all the genes in a population at any given time is known as the gene pool.

Question 2

What is the allele frequency?

Answer 2

The relative frequency of a particular allele in a population is the allele frequency.

Question 3

What does the Hardy-Weinberg principle state?

Answer 3

“In a stable population with no disturbing factors, the allele frequencies will remain constant from one generation to the next, and there will be no evolution”

Question 4

What is the Hardy-Weinberg principle expressed at?

Answer 4

p2+2pq+q2=1

Question 5

What factors affect evolution?

Answer 5

• Mutation
• Sexual selection
• Gene flow (movement of alleles between populations)= immigration and emigration
• Genetic drift
• Natural selection

Question 6

What is stabilising selection?

Answer 6

Stabilising selection is when individuals with alleles for average/normal characteristics are more likely to survive and reproduce.

Question 7

When does directional selection occur?

Answer 7

Directional selection occurs when there’s a change in the environment and individuals with extreme phenotypes are more likely to survive and reproduce.

Question 8

What is directional selection?

Answer 8

Natural selection that favours one extreme phenotype.

Question 9

What is disruptive selection?

Answer 9

Natural selection that favours both extremes of a given phenotype.

Question 10

What is codominance?

Answer 10

Co-dominance occurs when two different alleles occur for a gene- both of which are equally dominant.

Question 11

What is autosomal linkage?

Answer 11

Genes present on the same, non-sex chromosome.

Question 12

What is epistasis?

Answer 12

Epistasis is the effect of one gene on the expression of another gene.

Question 13

What is the founder effect?

Answer 13

When a few individuals of a species colonise a new area

Question 14

What is speciation?

Answer 14

Speciation is the formation of new species through the process of evolution.

Question 15

What is allopatric speciation?

Answer 15

Speciation that occurs as a result of a physical barrier (e.g river or sea) between populations- they are geographically isolated

Question 16

What occurs as a result of allopatric speciation?

Answer 16

• The environments of the different groups will often be different and so will the selection pressures resulting in different physical adaptations
• This leads to genetic drift

Question 17

What is sympatric speciation?

Answer 17

Speciation that occurs when there is no physical barrier between populations.

Question 18

When does sympatric speciation occur?

Answer 18

• Members of two different species interbreed and form fertile offspring
• The hybrid formed, which is a new species, will have a different number of chromosomes to either parent and may no longer be able to interbreed with members of either parent population.
• This stops gene flow and reproductively isolates the hybrid organisms.

Question 19

What is a polymorphic allele?

Answer 19

A gene with more than two possible alleles.

Question 20

What is artificial selection/selective breeding?

Answer 20

Selection of individuals for breeding with desirable characteristics.