question_answer 59)

  In human beings, the statistical probability of getting either a male or female child is 50 : 50. Give a suitable explanation.

Answer:

                  The sex of an infant is determined by the type of sex chromosome contributed by the male gamete. A male produces two types of sperms-one type bears 22 + X composition and the other, 22 + Y, Therefore, a male have 50% sperms with X-chromosomes and other 50% with Y-chromosome. Any one of the two types of sperms can fertilize the egg. If a Y-bearing sperm fertilizes the egg, the zygote will be XY (male) and when an X-bearing sperm fertilizes the egg, the resulting zygote will be XX (female). Since the ratio of X-chromosome and Y-chromosome in male gamete is 50 : 50. The statistical probability of male or a female infant is also 50: 50.