Question

In which type of inheritance the results are affected by reciprocal cross?
A. Nuclear
B. Cytoplasmic
C. Blending
D. All of the above

Answer 1

Hint:-Reciprocal cross is a kind of crossing technique, which implies making crosses between a pair of parents A and B by using them in turn to obtain two reciprocal crosses of A, Band B, A as female parent and male parent. Typically a cross is represented in the manner that the first parent is female and the second parent is male.

Complete Answer:-Nuclear- The nuclear genomes are diploid and distinguished by dysomic inheritance and sexual reproduction in most higher eukaryotic species. So nuclear genes come in pairs of allelics, which are also subtly distinct from each other. Gametes resulting from meiosis are haploid and carry a single allele only. One nuclear allele of each gene from each parent is inherited by the zygote that results from fertilization. Cytoplasmic organelles, on the other hand, normally contain numerous, homogeneous genomes that are generally only inherited from one parent.

Cytoplasmic- The inheritance of the characteristics of only one of the two parents, typically the female parent to the progeny, is known as cytoplasmic inheritance. A reciprocal cross is a breeding experiment in genetics designed to assess the role of parental sex in a given pattern of inheritance. In order to conduct such an experiment properly, all parent species must be true breeders. A male expressing the trait of interest will be crossed in one cross with a female not expressing the feature. If some genetic information is also carried in the cytoplasm, a way of detecting it should be provided by the unequal contribution of the cytoplasm to the zygote by both gametes. The reciprocal cross is the method used for this.

Blending- An inheritance in which the parent characters tend to merge to form an intermediate state in the offspring, and in which in later generations there is no obvious segregation. In Darwin's time, it was the mechanism postulated to rapidly homogenise heritable variation among individuals. Any detectable difference among individuals would be environmentally induced under the blending inheritance, and Darwin's postulated mechanism would be unable to produce any lasting change.



Hence, the correct answer is (b) Cytoplasmic

Note:- The observation that no dysgenesis is produced by the reciprocal cross indicates the presence in the female germ line of a cytoplasmic factor which prevents this mobilisation. Recent work indicates that small Piwi-interacting RNAs are composed of this element.