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Which one of the following conditions correctly describes the manner of determining the sex?

Correct answer: B. XO type of sex chromosomes determine male sex in grasshoppers

  • A. Homozygous sex chromosomes (ZZ) determine female sex in birds
  • B. XO type of sex chromosomes determine male sex in grasshoppers
  • C. XO condition in humans as found in Turner's syndrome, determines female sex
  • D. Homozygous sex chromosomes (XX) produce male in Drosophila

Explanation

The correct answer is that the XO type of sex chromosomes determines male sex in grasshoppers. In these species, males have only one X chromosome (XO), making them heterogametic, while females have two X chromosomes (XX), making them homogametic. This system is part of the XX-XO type of sex determination. In contrast, birds have females with ZW sex chromosomes and males with ZZ. In humans, the typical female configuration is XX, while Turner's syndrome (XO) results in a female phenotype with health issues. Drosophila males have XY sex chromosomes, not XX.

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About Inheritance

Mendel's laws explain segregation, independent assortment and the prediction of genetic ratios using alleles, genotypes and phenotypes. The chapter also covers linked genes, recombination and crossing over during meiosis, then applies pedigree reasoning to X-linked recessive traits, which show different inheritance patterns in males and females.

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