Question

1. Tom has blood type AB. Show all possible genotypes for this blood type.

2. If only males are affected in a pedigree, what is the likely inheritance pattern for the trait? Draw a three-generation pedigree showing the inheritance of the trait from an affected grandfather to an affected grandson. (No spouses are affected.)

3. If the parents are heterozygous for cystic fibrosis, what are the chance of a child having cystic fibrosis?

4. Mary has blood type A and Mateo has blood type B; can they be the parents of a child with type O blood? Explain why or why not.

5. Show a cross that would produce a phenotypic ratio of 1:1 among the offspring.

Answer 1

1. Blood group AB has the genotype AB. This is due to the phenomenon of co-dominance of A and B in blood grouping.

2)

Pedigree 7 Affected nocle unaffected wale Fersales 6 o 20

3) The child has 50% probability of inheriting the disease as both the parents are heterozygous.

4)The probability of the child getting an O blood group depends on whether Mary and Mateo are homozygous or heterozygous if homozygous the child cant inherit an O blood group. Only if the parents are heterozygous ie;Mary is AO and Mateo is BO , then the child can have O type blood group.

5) A cross for getting phenotypic ratio 1:1 may be obtained between a homozygous and a heterozygous individual of similar triat.

For example flowe color in Mirabilis jalapa (Incomplete Dominance)

Parents : WwX WW (w -red flowers , w - white flowers)

Gametes: W,w,W,w

Cross:

	W	w
W	WW (Red)	Ww (Pink)
W	WW(Red)	Ww (Pink)

Therefore phenotypic ratio is 1:1