question_answer

(i) Make a comparison between mammalian sperm and ovum.

(ii) Explain the permanent methods of birth control

OR

What is polyembryony? Give two reasons of polyembryony.

 

Answer:

(i) Following table shows the comparison between mammalian sperm and ovum:
	Sperm		Ovum
(i)	Minute and motile gamete,	(i)	Large and non-motile
(ii)	Narrow and elongated	(ii)	Rounded in shape
(iii)	Covered by plasma membrane	(iii)	Covered by corona radiata
(iv)	Three Body division: head middle piece and tail	(iv)	No such body divisions
(ii) Sterilisation provides a permanent birth control. It is called vasectomy in men and tubectomy in women. It involves the removal of a short segment of each vas deferens or oviduct and tying up of the remaining ends tightly with the surgical thread.
OR
Polyembryony is the phenomenon of development of more than one embryo in the same seed (1719) in Citrus.
The reasons are:
(a) Presence of more than one embryo in the same seed
(b) Cleavage of one embryo into two or more embryos