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The breeding experiment using an unknown genotype of grey and white mice, the following results were obtained.
If the grey female from cross IV were mated with the grey male from cross II, then which of the following would be true?

Parents

Offspring

Cross

Female


Male

Gray

White

I

Gray

X

White

82

78

II

Gray

X

Gray

118

39

III

White

X

White

0

50

IV

Gray

X

White

74

0

A. All of the offspring would be grey.
B. All of the offspring would be white.
C. Half of the offspring would be grey.
D. One-quarter of the offspring would be grey.
E. One-quarter of the offspring would be white.

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Last updated date: 19th Jun 2024
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Answer
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Hint: The law of dominance notes that, with the same feature, one trait will mask the existence of another trait in a heterozygote. The dominant allele would be expressed solely, rather than all alleles leading to a phenotype. The recessive allele will remain "hidden," but will be passed onto the offspring in the same way as the dominant allele is transmitted

Complete answer:
In the given table, cross III between white and white parents generate only white progeny which means that both white parents are homozygous here and the offspring is also pure breeding. Cross IV between grey and white parents create only grey offspring displaying the dominance of grey (G) allele over white (g). This cross also illustrates that parents are homozygous (GG and gg) here and the progeny is heterozygous dominant (Gg). Cross II amid grey and grey parents create both white and grey in roughly \[3:1\] ratio which means that both parents are heterozygous dominant (Gg) in this cross. Among total grey progeny of cross II, 2/3 will be heterozygous dominant (Gg) and 1/3 will be homozygous dominant (1/3).
Currently the cross between grey females (Gg) from cross IV and grey male of cross II (GG or Gg) will produce all grey offspring.

So, the correct answer is “Option A”.

Note:
The notion of inheritance units, which he called "factors," was invented by Mendel, one of which is a recessive trait and the other is dominant. Mendel said factors, later referred to as chromosomes, typically exist in pairs in ordinary body cells, but during the development of sex cells, they are separated. The actual sex cell becomes part of each member of the pair. The recessive gene, the white flower, will conceal the dominant gene, such as the purple flower in Mendel's plants.