Inheritance And Selection

Question 1

What is sex linkage?

Answer 1

When the gene is carried on the sex chromosome

Question 2

What is co-dominance?

Answer 2

Both alleles are dominant

Therefore if heterozygous the phenotype will express a mixture of both

Question 3

What is a gene pool?

Answer 3

Total number of alleles in a particular population at a given time

Question 4

What is the hardy-Weinberg principle?

Answer 4

Frequency of dominant and recessive alleles in a population will remain constant from generation to generation

Question 5

What does the hardy- Weinberg theory assume?

Answer 5

• population is large
• population is isolated
• mating is random
• no selection
• no migration

Question 6

How does selection change allele frequency?

Answer 6

• individuals with a combination of alleles express an advantage in their phenotype
  -lead to differential reproductive success
  -advantageous alleles in a population increase
  -Disadvantageous alleles decrease
  -allel frequency is changed over time
  -

Question 7

What is discontinuous variation?

Answer 7

• characteristics fall into distinct categories
• one or two genes control it
• little/no influence by the environment
• eg. Blood group

Question 8

What is continuous variation?

Answer 8

• don’t fall to categories, form a continuum
• usually under control of several genes
• usually influenced by the environment

Question 9

What is directional selection?

Answer 9

The selection pressure selects one extreme of the phenotype

-promotes the allele which encodes the other extreme

Question 10

What is stabilising selection?

Answer 10

The environment remains stable

• selection pressure acts on both extremes
• mean remains stable

Question 11

What classifies a species?

Answer 11

Group of organisms that:

• share similar characteristics
• reproduce fertile offspring
• occupy same niche

Question 12

What is speciation?

Answer 12

Evolutionary process by which new biological species arise

Question 13

What is speciation the consequence of?

Answer 13

Reproductive isolation which results in genotype and/or phenotype divergence

Question 14

What is allopatric speciation?

Answer 14

• geographical isolation leads to reproductive isolation

- favoured alleles are different for each population

Question 15

When doing a genetic diagram what is expected?

Answer 15

• fertilisation is random
• equal opportunity for survival
• many offspring