Inheritance

Question 1

Gene locus definition

Answer 1

The specific location of a gene on the chromosome

Question 2

‘Purebreeding parents’

Answer 2

Both parents are homozygous

Question 3

The recessive allele is only expressed…

Answer 3

in an individual who is homozygous recessive

Question 4

The dominant allele will only be expressed in..

Answer 4

both heterozygous and homozygous dominant individual

Question 5

Where a gene shows codominance or incomplete dominance…

Answer 5

both alleles will be expressed in the heterozygote

Question 6

‘Blending’ in the phenotype

Answer 6

Neither allele is completely dominant over the other

Question 7

Multiple alleles

Answer 7

More than two alleles

Question 7

Sex linkage

Answer 7

X chromosome is much larger and has many more genes not present on Y: they are not homologous
- so genes whose loci are on sex chromosomes have different inheritance patterns from genes on the autosomes
-disorders caused by recessive allele with an X locus will be + common in males, since a single recessive allele is sufficient for the trait to be expressed in phenotype

Question 8

Sex-linked genes

Answer 8

Genes with loci on an X chromosome