Question : Some events related to human reproduction are given below. Formation of placenta, First meiotic division, Cortical reaction, Ovulation, Fertilizin -antifertilizin reaction, Gastrulation. a. Arrange the events in sequential order. b. State why you arrange so.

Question : Some events related to human reproduction are given below.

1.	Question : Some events related to human reproduction are given below. Formation of placenta, First meiotic division, Cortical reaction, Ovulation, Fertilizin -antifertilizin reaction, Gastrulation. a. Arrange the events in sequential order. b. State why you arrange so.
Answer» Solution :a. First meiotic division `to` OVULATION Fertilizin-antifertilizin REACTION `to` Cortical reaction `to` GASTRULATION `to` Formation of placenta b.After the first meiotic division the ovulation occurs. After the fertilization, the fertilizin and antifertilizin occur. After the fusing of male and female nucleus, the cortical reaction takes place. Then gastrulation occurs and THREE germ LAYERS are formed and the form tion of placenta occurs..