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Dihybrid Cross of Mendel MCQ - Practice Questions with Answers

Edited By admin | Updated on Sep 18, 2023 18:34 AM | #NEET

Quick Facts

Dihybrid Cross is considered one of the most asked concept.
15 Questions around this concept.

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A Tall plant with Red seeds (both dominant traits) was crossed with a dwarf plant with white seeds. If the segregating progeny produced an equal number of tall red and dwarf white plants, what would be the genotype of the parents?

TtRr × TtRR

TtRr × ttrr

TTRR X ttrr

TTRR × TtRr

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Two interacting genes (independently assorting) were involved in the same pathway. Absence of either gene's function leads to absence of the end product of the pathway. A dihybrid cross involving the two genes is carried out. What fraction of the F2 progeny will show the presence of the end product?

$\frac{1}{4}$

$\frac{3}{4}$

$\frac{9}{16}$

$\frac{15}{16}$

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Concepts Covered - 1

Dihybrid Cross

Mendel also worked with and crossed pea plants that differed in two characters, as is seen in the cross between a pea plant that has seeds with yellow colour and round shape and one that had seeds of green colour and wrinkled shape.
Mendel found that the F1 progeny resulting from the crossing of the parents, had yellow coloured and round shaped seeds.
Thus, yellow colour was dominant over green and round shape dominant over wrinkled.
Let us use the genotypic symbols Y for dominant yellow seed colour and y for recessive green seed colour, R for round shaped seeds and r for wrinkled seed shape.
The genotype of the parents can then be written as RRYY and rryy.
The gametes RY and ry unite on fertilisation to produce the F1 hybrid RrYy.
When Mendel self hybridised the F1 plants he found that 3/4th of F2 plants had yellow seeds and 1/4th had green.
The yellow and green colour segregated in a 3:1 ratio.
Round and wrinkled seed shape also segregated in a 3:1 ratio; just like in a monohybrid cross.
In the dihybrid cross, the phenotypes round,yellow; wrinkled, yellow; round, green and wrinkled, green appeared in the ratio 9:3:3:1.
The phenotypic ratio of 9:3:3:1 occurs in 9 types of genotypes.
Such a ratio was observed for several pairs of characters that Mendel studied.