NEET BIOLOGY

GENETICS AND EVOLUTION

INHERITANCE AND VARIATION

Question [CLICK ON ANY CHOICE TO KNOW THE RIGHT ANSWER]
IF YOU CROSS A Gg X WITH A gg GOAT THE PHENOTYPIC RATIO IS ____
A
3:1
B
2:2
C
6:1
D
None of the above
Explanation: 

Detailed explanation-1: -To calculate the phenotypic ratio, we look at the observable traits – long (dominant) and short (recessive) phenotypes. Two babies have long hair (Ll) and two have short hair (ll). This gives us a phenotypic ratio of 2:2.

Detailed explanation-2: -Now, a pea with t he genes GG will be green is color, gg is yellow, and Gg is green due to the dominant gene, G. The GG, Gg, and gg above are known as genotypes. They denote the specific genes for that trait. The colors, yellow and green, are known as the phenotype, or the physical appearance of that genotype.

Detailed explanation-3: -The two alleles of any gene are segregated during the formation of gametes. Thus the green-pod parent (Gg) will produce two kinds of gametes-G and g. The yellow-pod parent (gg) will produce g gametes. As you can see, 1/2 of the offspring are genotype Gg and 1/2 are gg.

Detailed explanation-4: -Monohybrid Cross: F2 generation One-fourth of the F2 generation would be homozygous dominant (GG), one-half would be heterozygous (Gg), and one-fourth would be homozygous recessive (gg). The phenotypic ratio would be 3:1, with three-fourths having green pod color (GG and Gg) and one-fourth having yellow pod color (gg).

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