Question

Select the option that correctly identifies the number of correct statements.

I. Reciprocal cross is always a type of monohybrid cross
II. Test cross is always type of monohybrid cross
III. Back cross is always a type of monohybrid cross
IV. Back cross is a type of test cross
V. Test cross is a type of back cross

• A. 4
• B. 3
• C. 2
• D. 1

Answer 1

The correct option is D 1

The sentences given above mention different types of crosses that can be performed.
A monohybrid cross is a cross between two parents which differ in only one character.
Character refers to a heritable feature that varies among individuals. For example:- stem length, flower color, flower position, pod color, pod shape, seed color, seed shape, pod position.
Taking into account any one character between two plants, if a cross is made, then it would be a monohybrid cross.
A reciprocal cross is a cross in which traits of the male and female parents are switched. This means if in a particular cross, the male parent had yellow seeds and the female parent had green seeds, in the reciprocal cross the traits in the parents would be switched. This means in the reciprocal cross, the male parent would have green seeds and the female parent would have yellow seeds. A reciprocal cross does not take into account the number of characters under study, it only considers the reversal of the sex of parents for the concerned traits.
A test cross is done to find out whether a dominant trait exhibited by a plant is in homozygous or heterozygous condition. The plant expressing the dominant trait is crossed with a plant which is homozygous recessive for the same characteristic. Test cross also doesn’t necessarily take into account the number of characters under study.
In a back cross, an offspring is crossed with one of its parent plants. It also doesn’t take into account the number of characters under study.
A test cross is also a type of back cross. If one of the parents involved in the formation of an offspring is homozygous recessive, and the offspring is crossed with that particular parent, then it would be a back cross as well as a test cross. But the vice versa is not true.
So, only statement V is true i.e., only one statement is true.