A. Genital development B. Meiosis C. Mate recognition D. Courtship behavior Use

Question

A. Genital development B. Meiosis C. Mate recognition D. Courtship behavior Use the following passage for questions 2-9 Several species of Drosophila have X-linked e and f genes that affect the sex ratios of individuals offspring. However, the genes only affect sex ratios if they are brought close together by an inversion of one arm of the X-chromosome (Fig. 1). X, standard X X, inverted X Figure 1 Standard and inverted X chromosomes An X,Y male is standard: he sires equal numbers of sons and daughters. An XiY male expresses the sex ratio trait: he sires only daughters. Total reproductive output is not affected; X,Y males and XY males sire equal numbers of offspring. If none of the X-bearing genotypes (XY, XXi, or XX,) is selected against, then the frequency of Xi is expected to 100%, unless other genes act to suppress expression of e and f. Occasionally, XiY males sire viable but sterile sons of normal appearance. Genetic analyses show that all these sons are XO, inheriting the X chromosome from their mother and lacking a Y chromosome.

Explanation / Answer

Ans- in this case the (b) meiosis is disrupted because the remaining are not disrupted as mentioned in passage. They mate with their own species so their mate recognition and courtship behaviour are good and they can produce offsprings so genital development is also not disrupted. Meiosis is used for sexual reproduction to produce haploid cells which are different from one another and both of the parents. When meiosis is disrupted the x linked gene will affect sex ratio.

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