IGCSE Biology - Monohybrid Inheritance & Codominance

A man of genotype I^AI^o and woman of genotype I^BI^o have a child.

What is the chance that the child will have the same blood group as one of its parents?

• 0

• 1 in 4

• 1 in 2

• 3 in 4

What term is used to describe a version of a gene?

• allele

• genotype

• phenotype

• heterozygous

What term is used to describe an organism that carries two identical alleles for a gene?

• dominant

• recessive

• homozygous

• heterozygous

What term is used to describe an organism that carries two different alleles for a gene?

• dominant

• recessive

• homozygous

• heterozygous

What term is used to describe the observable features of an organism due to its genotype?

• inheritance

• phenotype

• dominant

• allele

Which of the following statements are true of codominance?

I. Both alleles are expressed in a person who is heterozygous

II. More than two phenotypes are usually possible

III. The ABO blood group system is an example of it

• I and II only

• I and III only

• II and III only

• I, II and III

Gary and Fiona are both healthy but produce a child with a genetic disease caused by a recessive allele.

Which of the following must be true?

• The child could be heterozygous

• Gary is homozygous and Fiona is heterozygous

• Gary and Fiona are both homozygous

• Gary and Fiona are both heterozygous

A plant has two different alleles of a gene, G, resulting in it having a green seed.

Which row of the table describes the phenotype and genotype of the seeds of this plant?

• A

• B

• C

• D

A person has the genotype Aa.

What is the correct description of this genotype?

• heterozygous, with two different alleles of the same gene

• heterozygous, with two different genes of the same allele

• homozygous, with two different alleles of the same gene

• homozygous, with two different genes of the same allele

Albinism is humans us caused by a recessive allele. It causes the skin and hair to appear white.

Parents who do not have this condition produce a child with abinism.

What is the probability that their second child will be born with albinism?

• 25%

• 50%

• 75%

• 100%