Inheritance Practice Questions

A rabbit has the genotype Bb.

This rabbit is

Put a cross ( ☒ ) in the box next to your answer.

A homozygous dominant

B heterozygous

C homozygous recessive

D a gamete

State the phenotype of a rabbit with the genotype bb.

Explain why a rabbit with the genotype BB and a rabbit with the genotype Bb have the same phenotype.

State the sex chromosomes found in the body cells of a human male.

Complete the Punnett square below to show how the sex of a child is determined at fertilisation.

The top row shows the gametes from the mother. The left column shows the gametes from the father.

	X	X
X
Y

Use your Punnett square to give the percentage probability that a child will be female.

Which of these is an example of environmental variation in a population of foxes?

Put a cross ( ☒ ) in the box next to your answer.

☐ A fur colour

☐ B eye colour

☐ C a tear in the ear caused by a fight

☐ D blood group

The body mass of a person is affected by their environment as well as by their genes.

Give two environmental factors that could affect the body mass of a person.

Complete the Punnett square below to show the genotypes of the offspring from this cross.

The top row shows the gametes from one parent. The left column shows the gametes from the other parent.

	R	r
R
r

Use your Punnett square to give the expected ratio of purple-stemmed offspring to green-stemmed offspring.

The cross produced 360 seedlings.

Calculate the expected number of seedlings with green stems.

Explain how Figure 1 shows that PKU is caused by a recessive allele.

The dominant allele is N and the recessive allele is n.

State and explain the genotype of individual 4.

Complete the genetic diagram below to show how the sex of a chicken is determined at fertilisation.

Parent genotypes: male ............ × female ............

Gametes: ...... ...... ...... ......

Offspring genotypes: ...... ...... ...... ......

Give the expected ratio of male chicks to female chicks produced by this cross.

Explain why, in birds, it is the female parent that determines the sex of the chick.

Two kittens from the same litter have the same parents, but one kitten has black fur and the other has ginger fur.

Explain why these two kittens have different fur colours.

There is usually extensive genetic variation within a wild population of rabbits.

Explain how mutations produce this genetic variation and describe the range of effects a mutation can have on the phenotype of a rabbit.

Which statement about phenotypic features is correct?

Put a cross ( ☒ ) in the box next to your answer.

☐ A every phenotypic feature is controlled by one gene only

☐ B most phenotypic features are controlled by more than one gene

☐ C phenotypic features are not affected by alleles

☐ D all phenotypic features are controlled only by the environment

Identical twins have the same alleles for the genes controlling skin colour.

One twin works outdoors and has darker skin than the other twin, who works indoors.

Explain why the twins have different skin colours.

A private company offers to sequence the whole genome of any person who pays a fee. The company sends the person a report listing the alleles they have.

Discuss the benefits and the drawbacks to a person of having their genome sequenced, including how the information could be used in medicine.

Deduce the genotype of the bull.

Use a genetic diagram in your answer.

The same bull is later mated with a heterozygous cow.

Calculate the probability that a calf from this mating will have horns.

Explain why all of the F1 offspring had short hair.

Two of the F1 guinea pigs were then crossed with each other. This cross produced 48 offspring in total.

Calculate the expected number of these offspring with long hair.

Calculate the probability that the first two offspring born from this cross both have long hair.