19. (a) What provides nutrition to human sperms ? State the genetic
constitution of a sperm.
(b) Mention the chromosome pair present in zygote which determines
the sex of (i) a female child, and (ii) a male child.
Answers
Explanation:
(a) The secretions of the prostrate glands and seminal vesicles give the sperm nutrition. The sperm consists of 22 + X or 22 + Y chromosome
(b) (i) XX chromosome
(ii) XY chromosome
a) Sertoli cell provides nutrition to sperm cells. The genetic make up of sperm is one sex chromosome and 22 autosomes and is haploid.
b) the chromosome pair present in zygote which determines
the sex of female child XX male child XY
Explanation:
Spermatogenesis (formation of sperm cells) takes place in sertoli cells or nurse cells of testes. The growing sperm or spermatozoa gets its nutrition and blood supply from sertoli cells. Sertoli cell secretes various hormones and factors which comes into action at various stages.
The gametes of the male parent is called spermatozoa. The human sperm is haploid and contains only one sex chromosome either X or Y and 1 set of autosomal chromosomes or 22 autosomal chromosomes. The sperm is heterogametic. There are 3 billion bases constituting genes in human are present in sperm.
b) XX chromosome determines the sex of female child
XY chromosome determines the sex of male child.
During fertilization either X or Y chromosome fuses with female gamete or egg depending upon the type of zygote formed the male or female child is produced. It can be either XX or XY.
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