Question

Which one of the following conditions of the zygotic cell will produce a normal human female child?
A. Only heterologous X chromosome
B. One X and one Y chromosome
C. Two homologous X chromosome
D. Only one Y chromosome

Answer 1

Hint: As we know, the zygote form as a result of fusion of male and female gametes. As we know the male father contains X and Y chromosomes and the female parent contains two XX chromosomes. So, when X chromosomes of females fuse with X chromosomes of male, a female child is born.

Complete answer:
In this question, we have asked about the chromosomes of normal female zygotes. As we know, zygote forms when male and female gametes fuse. These gametes contain chromosomes. As we know, gametes are haploid and the gametes contain 23 chromosomes. The female have two sex chromosomes, which are two X chromosomes. The gamete is formed by meiosis, so the female gamete will have 22+X chromosomes and in male 2 sex chromosomes are found: X and Y. So, the male gamete will have either 22+X or 23+Y. When the Y chromosome is present in the male gamete and it fuses with the X chromosome of the female, a male zygote is formed with 44+XY chromosome. When the X chromosome is present in the male gamete and it fuses with the X chromosome of the female, a female zygote is formed with 44+XX chromosome.

So, the correct option for female zygote is C. Two homologous X chromosomes.

Note:
Sometimes, the sex chromosomes doesn't separate from each other during gamete formation. So, the child forms with 44+XXY chromosomes and the child has 47 chromosomes. This condition is known as Klinefelter's syndrome. In this disease the child has a male body but gynecomastia and other feminine characteristics produce at puberty. The person with Klinefelter Syndromes is infertile.