NCERT Solutions for Class 8 Science Chapter 10
Important NCERT Questions
8th Chapter 10 Reaching the Age of Adolescence
NCERT Books for Session 2022-2023
CBSE Board and State Board
Questions No: 8 Part: c
Write notes on: Sex determination in the unborn baby.
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Sex determination in the unborn baby: All human beings have 23 pairs of chromosomes in the nuclei of their cells. Out of these two chromosomes are the sex chromosomes, named X and Y. A female has two X chromosomes, while a male has one X and one Y chromosome. The gametes (egg and sperm) have only one set of chromosomes. The unfertilised egg always has one X chromosome but sperms may have X or Y. When a sperm containing X chromosome fertilises the egg, the zygote would have two X chromosomes and develop into a female child. If the sperm contributes a Y chromosome to the egg (ovum) at fertilisation, the zygote would develop into a male child. This concludes that the sex chromosomes of the father determine the sex of an unborn baby.
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Sex determination in an unborn baby occurs at conception. Humans possess 23 pairs of chromosomes in most cells, including one pair called sex chromosomes. Females typically have two X chromosomes (XX), while males have one X and one Y chromosome (XY).
At fertilization, if a sperm carrying an X chromosome fertilizes the egg, the combination (XX) results in a female baby. However, if a sperm carrying a Y chromosome fertilizes the egg, the combination (XY) leads to the development of a male baby. The sex of the unborn baby is determined by the combination of chromosomes inherited from the parents during conception, dictating the baby’s development as male or female.