Patterns of inheritance

Question 1

Phenotypic variation

Answer 1

The differences in genotype result in variation of the phenotype eg human blood groups alleles

Question 2

Polygenic variation

Answer 2

Inherited characteristics that shows continuous variation are usually inherited my many genes,

Question 3

Monogenic

Answer 3

Inherited characteristics that shows discontinuous variation are usually influenced by only one gene and are known as monogenic

Question 4

What is a gene?

Answer 4

A sequence of bases on a DNA molecule that codes for a protein which results in a characteristic eg gene for eye colour

Question 5

Allele

Answer 5

Different version of a gene. Most plants and animals have two alleles of each gene one from each parent - the order of bases in each allele is slightly different they code for different versions of the same characteristic

Question 6

Genotype

Answer 6

The alleles an organism has

Question 7

Dominant

Answer 7

An allele whose characteristic appears in the phenotype even when there’s only one copy. Dominant alleles are shown by a
capital letter. E.g. the allele for brown eyes (B) is dominant — if a person’s genotype is Bb or BB, they’ll have brown eyes.

Question 8

Recessive

Answer 8

An allele whose characteristic only appears in the phenotype if two copies are present and are showed by a lowercase letter

Question 9

Codominant

Answer 9

Alleles that are both expressed in the phenotype neither one is recessive

Question 10

Locus

Answer 10

The fixed position of a gene on a chromosome. Alleles of a gene are found at the same locus on each chromosome in a pair

Question 11

Homozygote

Answer 11

An organism that carries two copies of the same allele

Question 12

Heterozygote

Answer 12

An organism that carries two different alleles

Question 13

Carrier

Answer 13

A person carrying an allele which is not expressed in the phenotype but that can be passed onto offspring.