Question

The allele for black hair(B) is dominant over brown hair(b) and the allele for a brown eye(E) is dominant over the blue eye(e). Out of the offsprings obtained upon mating a black-haired and brown-eyed individual (BbEe) with a brown-haired and brown-eyed individual (bbEE), the ratio of brown-haired and brown-eyed individuals to black-haired and brown-eyed individuals is?
A. 2:1
B. 3:1
C. 1:1
D. 1:2

Answer 1

Hint: Mendel's law of autonomous collection expresses that qualities don't impact each other as to the arranging of alleles into gametes: each conceivable blend of alleles for each quality is similarly prone to happen. The autonomous variety of qualities can be delineated by the dihybrid cross: a cross between two genuine reproducing guardians that express various attributes.

Complete answer:
The traits that are shown with a Capital letter are dominant and a lower case is recessive– Brown Eyes (E) Blue Eyes (e) and black hair(B) and brown hair(b).
The ratio can be obtained by a cross between a black-haired and brown-eyed individual (BbEe) with a brown-haired and brown-eyed individual bbEE.

Parents BbEe bbEE
                                           ↓ ↓
Gametes: BE, Be, bE, be bE, bE, bE, bE

F1 generation: By using the punnett square test:

Gametes	bE	bE	bE	bE
BE	BbEE(black hair, brown eye)	BbEE( black hair, brown eye)	BbEE (black hair, brown eye)	BbEE (black hair, brown eye)
Be	BbEe( black hair, brown eye)	BbEe (black hair, brown eye)	BbEe (black hair, brown eye)	BbEe (black hair, brown eye)
bE	bbEE(brown hair and brown eye)	bbEE(brown hair and brown eye)	bbEE(brown hair and brown eye)	bbEE(brown hair and brown eye)
be	bbEe(brown hair and brown eye)	bbEe(brown hair and brown eye)	bbEe(brown hair and brown eye)	bbEe(brown hair and brown eye)

Hence, the ratio of brown-haired and brown-eyed individuals to black-haired and brown-eyed individuals is- 1:1.

So, the correct answer is “Option C 1:1 ”.

Note:
A dihybrid cross depicts a mating test between two living beings that are indistinguishably mixture for two qualities. A half-breed living being is a heterozygous one, which implies that it conveys two unique alleles at a specific hereditary position, or locus. The strong connection between alleles for every attribute was at that point known to Mendel when he made this cross. The reason for the dihybrid cross was to decide whether any relationship existed between various allelic sets.