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

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

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?

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 person has the genotype Aa.

What is the correct description of this genotype?

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?

The pedigree chart shows the inheritance of a genetic disorder in a family.

What conclusion can be made about this genetic disease?

The pedigree chart shows the inheritance of a genetic disorder in a family.

What conclusion can be made about this genetic disease?

The pedigree chart shows the inheritance of a genetic disorder in a family.

It is caused by a recessive allele, h.

What conclusion can be made about the people in the chart?

Which of the following genotypes are possible for a person of blood group A?

I. I^A I^A

II. I^A I^B

III. I^A I^O

Night-blindness is a genetic disorder caused by a dominant allele.

The pedigree chart shows the inheritance of this disorder in a family.

Person X marries someone with normal sight.

What is the probability of them having a child with night blindness?

Coat colour in a certain mammal is determined by two codominant alleles of a gene.

Allele B produces a black coat and allele W produces a white coat.

What would you expect the phenotype to be of a mammal who is heterozygous for this gene?

Patrick is blood group AB.

Samantha is blood group A. However, her father was blood group O.

They have a child.

What is the probability that this child has the same blood group as Patrick or Samantha?

In a certain plant, the allele fo white fruit (W) is dominant over the allele for yellow fruit (w).

A white-fruited plant was crossed with a yellow-fruited plant.

About half of the offspring were white-fruited and the other half were yellow-fruited.

Which genotypes did the parent plants have?

In a certain animal, B s the dominant allele for normal skin without spots) and b is the allele for spotted skin.

A pair of these animals is crossed and they produce 37 offspring: 18 with spots and 19 without spots.

What are the most likely genotypes of the parents?

The colour of a mouse's fur is controlled by a single pair of alleles.

A mouse with black fur was crossed with a mouse with white fur. All of the offspring had black fur.

What would be the likely ratio in several generations of offspring, if two of these black offspring were crossed?

The pedigree chart shows the inheritance of a genetic disorder in a family.

It is caused by a recessive allele.

Which person in this pedigree chart has two possible genotypes?

The diagram shows the inheritance of coat colour in pigs through three generations.

What is the most likely explanation of how coat colour in pigs is inherited?

I. codominant alleles are involved

II. sandy pigs are heterozygous

III. the allele for a red coat is dominant