Question

Back cross is a cross between
A. $F_1\times F_1$
B. $F_1\times$ Recessive
C. $F_1\times$ Dominant
D. $F_1\times$ any parent

Answer 1

Hint: A genetic cross means the mating of the two individuals that result in the combination of two genetic materials from the mother and father to offsprings.

Complete Answer:
Back cross: Backcross is the cross between the hybrid organism with that of any of its parents. Hybrid organism produced in the $F_1$ generation. Backcross is also called the topcross.
Example – When we cross a pea plant consisting Green colour pod YY with a pea plant consisting yellow coloured pod yy.
Green coloured pod is dominant over the yellow coloured pod.
In the $F_1$ generation , we get the hybrids i.e. Yy. As Y is dominant and y is recessive so the hybrids show green coloured pods.
The hybrid Yy crosses with the dominant parent i.e YY, green coloured pod.
The result shows the all green coloured pod plants with two types of genotypes – YY amd Yy.
Genotypic ratio – 1:1
Phenotypic ratio – 100% green coloured pod pea plants.

Cross between the dominant (YY) parent and recessive (yy) parents:

	Y	Y
y	Yy	Yy
y	Yy	Yy

Cross between the hybrids (Yy) obtained in $F_1$ Generation with dominant (YY) parent:

	Y	Y
Y	YY	YY
y	Yy	Yy

Hence, option D is the correct answer for this question.

Note: The backcross is useful in isolating certain characters in a related group of plants and animals. This type of cross is used in horticulture, animal breeding and in production of gene knockout organisms.