Question

To determine whether \[{{F}_{1}}\] hybrid is homozygous or heterozygous for a particular trait ……..cross is performed.
A. Monohybrid
B. Test
C. Back
D. Reciprocal

Answer 1

Hint: The crossing in genetics refers to the deliberate breeding of two organisms to obtain and assess the offspring. Various kinds of genetic crosses are done to assess different characteristics of parents or offspring. A type of cross is performed to test the degree of similarity in alleles. This was developed by Gregor Mendel.

Complete answer: The genetic crossing is a technique that is used to check and analyze the inheritance and expression of genotypes from parents to offspring. Deliberate breeding in between compatible parents results in offspring that is either heterozygous or homozygous.
-Heterozygous means a pair of alleles with different traits is present in an organism. On the other hand, the homozygous means a pair of an allele that shows similar traits. The very first cross between pure parents produces \[{{F}_{1}}\] hybrid. The progeny is a hybrid of the traits inherited from both parents. Now, if one needs to know the nature of the zygosity of the \[{{F}_{1}}\] hybrid a test cross is performed.
In a test cross, deliberate crossing over is performed between the \[{{F}_{1}}\] hybrid and the homozygous recessive organism or parent. The resulting progeny confirms whether the \[{{F}_{1}}\] hybrid is homozygous or heterozygous. If the progeny comes out to be phenotypically dominant then the tested organism is inferred as homozygous dominant. If the progeny comes out to be half phenotypically dominant and half phenotypically dominant, then one can know that the test organism is heterozygous dominant. A monohybrid cross is that which involves deliberate breeding between homozygous pure parents showing opposite traits. This cross considers the inheritance of a single trait. A single trait is focused and tracked to assess its effects. For example, performing a monohybrid cross for the trait of the height of the plants. A back cross is done in between the \[{{F}_{1}}\] hybrid and one of its homozygous pure parents. A back cross can be considered as a test cross but a test cross is not always a back cross as any homozygous recessive organism can be used instead of the parent. A reciprocal cross on the other hand involves a pair of crosses done to test the role of parental sex on the inheritance pattern. It consists of a reversal of sexes related to each genotype.
Therefore, from the above discussion, we can conclude that the right answer is option B.

Note: Alleles are a pair of genes showing alternative traits and are present in the same place on the chromosome. One of the alleles is dominant and the other is recessive. The dominant allele is present to express itself even when present along with the recessive allele. This condition is called heterozygous dominant. On the other hand, the recessive allele needs to be paired with another recessive allele to express itself. This is called homozygous recessive.