Asked in Premeth Test 27 — InheritanceModerate

Which one of the following conditions of the zygotic cell would lead to the birth of a normal human female child?

Correct answer: A. Two X chromosomes

  • A. Two X chromosomes
  • B. Only one Y chromosome
  • C. Only one X chromosome
  • D. One X and one Y chromosome

Explanation

In human genetics, the presence of two X chromosomes (XX) in a zygote results in the development of a female child. This is because females are homogametic, meaning they have two of the same kind of sex chromosome, XX. Males, on the other hand, are heterogametic with one X and one Y chromosome (XY).Option A is correct because two X chromosomes indicate a normal female.Option B is incorrect because a single Y chromosome without an X does not support normal human development.Option C is incorrect because a single X chromosome, while resulting in a female, often leads to Turner syndrome, which is not a typical female development.Option D is incorrect because one X and one Y chromosome indicates a normal male child.

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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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