Question

In a dihybrid cross AABB * aabb, \[{F_2}\] progeny of AABB, AABb, AaBB and AaBb occurs in the ratio of
A. 1:1:1:1
B. 9:3:3:1
C. 1:2:2:1
D. 1:2:2:4

Answer 1

Hint: Genetics is a study of hereditary.
Genetics deals with the inheritance as well as the variation of characters from parents to offspring.
Inheritance is the process by which characters are passed on from one generation to another generation. (From parents to offspring.)

Complete answer:
Genetics is the study of hereditary (Transmission of characters from parents to offspring).
George Mendel conducted hybridization experiments on garden pea for seven years and proposed the laws of inheritance in living organisms.
He gave three laws:
1. Laws of segregation.
2. Law of independent assortment
3. Law of dominance.
Genes: Genes are the unit of inheritance.
Alleles: Genes which code for a pair of contrasting traits.
Monohybrid cross: A monohybrid cross is defined as the cross happening in the \[{F_1}\] generation offspring of parents differing in one trait only.
Dihybrid cross: A dihybrid cross is a cross that happens \[{F_1}\] generation offspring differ in two traits.
\[{F_1}\] progeny: \[{F_1}\] are offspring produced by crossing traits of parents.
\[{F_2}\] Progeny are offspring produced by crossing traits of offspring produced in \[{F_1}\] generation.
In a dihybrid cross AABB * aabb, \[{F_2}\] progeny of AABB, AABb, AaBB and AaBb occurs in the ratio of
AABB aabb
  ↓ ↓
  AB ab

So, the gametes are AB, Ab, aB, ab.

	AB	Ab	aB	ab
AB	AABB	AABb	AaBB	aAbB
Ab	AABb	AAbb	AaBb	Aabb
aB	AaBB	AaBb	aaBB	aaBb
ab	AaBb	Aabb	aaBb	aabb

So, AABB: AABb: AaBB: AaBb
So, 1:2:2:4

So, the correct option is option D. 1:2:2:4.

Note:
Law of segregation: It states that during gamete formation, the two alleles at a gene locus segregate from each other; each gamete has an equal probability of containing either allele.
Law of independent assortment: It states that genes for different traits assort independently of one another in the formation of gametes.
Law of dominance: It states that in a heterozygote, one trait will conceal the presence of another trait for the same characteristic.