Question

The crossing of an organism with a double (homozygous) recessive in order to determine whether it is homozygous or heterozygous for a character under consideration is known as
A.Back cross
B.Test cross
C.Reciprocal cross
D.Dihybrid cross

Answer 1

Hint: A genetic cross is the mating of the two individuals which results in the combination of the genetic information of the two different parents in the offspring or new ones. Genetic cross occurs between the haploid gametes and results in the diploid zygote.

Complete answer:
1.Back cross:
Backcross is the cross between the hybrid organism with that of any of its parents.
Hybrid organism produced in the generation.
Backcross is also called the topcross.
2.Test cross:
Test cross was first introduced by Gregor Johann Mendel.
Test cross is the crossing of an organism with a double (homozygous) recessive in order to determine whether it is homozygous or heterozygous for a certain character.
Individuals that are heterozygous have one dominant character and one recessive character.
Those who are recessive homozygous have two recessive alleles and those who are dominant homozygous have two dominant alleles.
3.Reciprocal cross:
Reciprocal cross is a cross with the phenotype of each sexes reversed as compared with that of the original cross.
Example- if the original cross is taking place between the A (female) and B (male) then the reciprocal cross will be in between the B (female) and A (male).
4.Dihybrid cross:
Gregor Mendel performed dihybrid cross on the pea plants.
Dihybrid cross is a cross between the two different characters/genes that differ in two observed traits.
For example – the cross between the dominant yellow coloured seeds and Round seeds (RRYY) and green coloured seeds and wrinkled seeds (rryy).
Here there are two traits involved in this cross i.e. seed colour and seed shape that’s why it is called a dihybrid cross.
Therefore, it has been clear from the above discussion that the crossing of an organism with a double (homozygous) recessive in order to determine whether it is homozygous or heterozygous for a character under consideration is known as test cross.

Hence the correct answer is option(B)
Note: The genetic makeup of any individual is called a genotype. Genotype is a set of heritable genes that can be passed down from parents to the offsprings. And the observable physical property of an organism is called its phenotype such as organism’s behaviour, appearance, development, etc.