Inheritance, Selection & Speciation

Question 1

Define allele

Answer 1

One alternative form of a given allelic pair

Question 2

Define dominant allele

Answer 2

Expresses when homozygous and heterozygous at the expense of the recessive allele

Question 3

Define recessive allele

Answer 3

Only expresses when homozygous

Question 4

Define genotype

Answer 4

The specific allelic combination for a certain gene

Question 5

Define phenotype

Answer 5

The outward expression of a particular trait

Question 6

Define Codominance

Answer 6

Two equally dominant alleles which both contribute to the phenotype

Question 7

Define sex-linked genes

Answer 7

Carried on the X chromosome, making it more common in men than womengene

Question 8

Define multiple alleles

Answer 8

More then two versions of the gene

Question 9

Name the two types of genetic diagrams

Answer 9

• Punnet squares

- FOIL method

Question 10

Give three reasons why interbreeding between species may not occur

Answer 10

• Different courtship behaviours
• Different breeding season
• Egg and sperm are no longer compatible so they cannot fuse

Question 11

Define directional selection

Answer 11

Favours individuals which vary in one direction from the mean eg/ longer fur

Question 12

Define stabilising selection

Answer 12

Favours average individuals (due to unchanging conditions)

Question 13

Why does every species over produce offspring?

Answer 13

• Those with the most advantageous alleles will survive
• The others will die
• Advantages vary in different habitats