What is the usual phenotypic ratio in the second generation of Mendel’s monohybrid cross?
Answer and explanation
Correct answer: 3:1
The governing concept is segregation of alleles in a monohybrid cross. If the F1 hybrids are Tt, the cross Tt × Tt produces TT, Tt, Tt and tt in a 1:2:1 genotypic ratio. Because TT and Tt are both tall while tt is dwarf, the phenotypic ratio is three tall plants to one dwarf plant, or 3:1. Therefore option A is correct.
Frequently asked questions
What is the correct answer to this question?
3:1
Why is this the correct answer?
The governing concept is segregation of alleles in a monohybrid cross. If the F1 hybrids are Tt, the cross Tt × Tt produces TT, Tt, Tt and tt in a 1:2:1 genotypic ratio. Because TT and Tt are both tall while tt is dwarf, the phenotypic ratio is three tall plants to one dwarf plant, or 3:1. Therefore option A is correct.
Which subject and chapter does this question cover?
This is a Class 10 Science question. Chapter: Heredity and Evolution. Topic: Mendel’s laws.
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