Question

1. Circle, underline or write in all of the homozygous genotypes listed below. og Aa AA 2. In pea plants, the dominant allele Pencodes purple flowers and the recessive allele p encodes white flowers. A plant with a pp genotype is crossed with a plant with a Pp genotype. What is the expected ratio of phenotypes in the offspring? Use a Punnett square to justify your answer. (0.5 points) 3. A mother has type A blood and she has a child with type AB blood. Is it possible that the father had type o blood? Use a Punnett square to justify your reasoning.

Answer 1

1. Homozygous genotypes are referred when the organism consists of two copies of the same allele for a gene. Thy are of 2 types:

a) Homozygous dominant (AA)- consists of 2 copies of same dominant allele

b) Homozygous recessive (aa)- consists of two copies of same recessive allele.

2. pp x Pp

	P	p
p	Pp	pp
p	Pp	pp

Phenotypic ratio: Purple (Pp) : white flowers (pp)

1:1

3. If A blood type mother mates with a O group father then the expected offsprings will be:

Genotype of mother= IaIo

Genotype of O blood group father= IoIo

IaIo x IoIo

	Io	Io
Ia	IaIo	IaIo
Io	IoIo	IoIo

Here it can be seen that there is no chance that an offspring with AB blood type will be born. Either a child with A blood group or O blood group will be born.

Therefore, the father of the child with AB blood group cannot have a father with O blood group as B antigen is required.