Inheritance

What is always found in female gametes and may be found in male gametes?

• A one X chromosome

• B one Y chromosome

• C two X chromosomes

• D one X chromosome and one Y chromosome

In some animals, B is the allele for normal skin (without spots) and b is the allele for spotted skin. A pair of these animals has 37 offspring, 18 with spots and 19 without. What are the most likely genotypes of the parents?

• A BB × BB

• B Bb × Bb

• C Bb × bb

• D bb × bb

The family tree shows the inheritance of the ability to taste a certain substance. The allele for the ability to taste this substance is dominant to the allele for the inability to taste it.

What is the chance of the second child of Peter and Hannah being a ‘non-taster’?

• A 1 in 1

• B 1 in 2

• C 1 in 3

• D 1 in 4

In cats, the allele for short hair is dominant to the allele for long hair. A short-haired cat and a long-haired cat had several families of offspring (kittens). All their kittens were short-haired. One of these kittens matured and mated with a long-haired cat. What would be the expected phenotypes of their offspring?

• A 1: 1 short to long

• B 3: 1 short to long

• C all long-haired

• D all short-haired

A gene for the colour of hair in mice has two alleles. B represents the allele for grey hair, and b represents the allele for white hair. A mouse with grey hair breeds with a mouse with white hair producing four offspring, with genotypes Bb, Bb, bb and bb. What are the genotypes of the parents?

• A both heterozygous

• B both homozygous dominant

• C one heterozygous and one homozygous dominant

• D one heterozygous and one homozygous recessive

What are alleles?

• A a pair of chromosomes

• B different versions of the same gene

• C the total number of genes on one chromosome

• D two genes side by side on the same chromosome

What results from meiosis of a diploid cell?

• A genetically different diploid cells

• B genetically different haploid cells

• C genetically identical diploid cells

• D genetically identical haploid cells

Some fruit flies have orange eyes and others have red eyes. If two orange-eyed fruit flies are crossed, their offspring always have orange eyes. If two red-eyed fruit flies are crossed, their offspring sometimes include both orange-eyed and red-eyed flies. What can be concluded from these observations?

• A Crossing an orange-eyed fly with a red-eyed fly will produce a 1: 1 ratio in the offspring.

• B The allele for orange eyes is dominant.

• C The allele for red eyes is dominant.

• D We could determine which allele is dominant only by doing a cross that produces a 3:1 ratio.

The diagram shows the chromosomes in the nucleus of a cell that divides by mitosis.

Which diagram shows the chromosomes in the nucleus of one of the daughter cells produced?

• A

• B

• C

• D

Albinism in humans is caused by a recessive allele. Parents who do not suffer from the condition produce an albino child. What is the probability that their second child will be born albino?

• A 25%

• B 50%

• C 75%

• D 100%