Question

A cross between AA and aa will produce an ${F_1}$ progeny________
a) Genotypically aa, phenotypically A
b) Genotypically AA, phenotypically a
c) Genotypically Aa, phenotypically A
d) Genotypically Aa, phenotypically a

Answer 1

Hint: A monohybrid cross is the one in which only one trait is used to make a cross between two parents. This cross yields the first generation of the offspring. If two characters or traits are used in a cross then it is known as the dihybrid cross.

Complete answer:
The cross between the AA and aa is a monohybrid cross. In this cross the AA is the dominant parent and the aa is the recessive parent. When they both are mated with each other then they lead to production of the offspring having a hybrid genotype which has both A and a in their genotype. All the offspring produced will not have any parental genotype. When these offspring are self-pollinated then they yield offspring which have a genotype of the first generation’s parents. The phenotype of the offspring produced in the first generation would show A character in them as this character is dominant over a character of the other parent. The cross made between the parents AA and aa can represented in the Punnett square below:

	A	A
a	Aa	Aa
a	Aa	Aa

So, we can say that the offspring obtained from the cross had Aa as their genotype which was different from the parental genotype and the phenotype of the offspring is A as it is the dominant trait.

So, the answer is ‘genotypically Aa, phenotypically A’.

Note:
The cross made between the pure homozygous parents always yields heterozygous offspring with the phenotype of the dominant parent being reflected by them. The cross made should be represented by the punnett square for proper representation.