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7. Which one of the following conditions correctly describes the manner of determining the sex in the given example? |
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Answer» Explanation:Sex determination in birds is of ZW-ZZ types in which females are HETEROMORPHIC (ZW) and males have homomorphic sex chromosomes (ZZ) which makes option A wrong. In roundworms and few insects (grasshopper), XX-XO mechanism of sex determination is present where females are homogametic (XX) but the male carries only one sex chromosome (XO). Hence the male grasshopper carries XO sex chromosomes; option B is correct. Human follows XY-XX mechanisms of sex determination wherein male is heterogametic and carries “XY” sex chromosome while female carries two copies of X-chromosomes (XX). The absence of part or full copy of one X-chromosome in the human female is "Turner SYNDROME" but the "XO" CONDITION is not female sex determinant. The option is C incorrect. The ratio of number of X-chromosome to that of a complete set of autosome determines the sex of Drosophila. The X/A value is 0.5 for a normal male. The option is D incorrect. |
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