Arrange the given events of fertilization pertaining to human in correct sequence of their occurrence.
A. Upward movement of sperms through vagina
B. Number of sperms surround the ovum
C. Coitus
D. Entry of a sperm into the egg
Answer & explanation
Correct answer: option 2
The correct answer is Option (2) → C, A, B, D
(C) Coitus — this comes first. Semen is released into the vagina of the female. Nothing else can happen before this.
(A) Upward movement of sperms through vagina — this comes second. The sperms swim up through the vagina and the uterus towards the fallopian tube.
(B) Number of sperms surround the ovum — this comes third. Many sperms reach the ovum in the fallopian tube and gather around it.
(D) Entry of a sperm into the egg — this comes last. Only one sperm enters the ovum. It can do so only after sperms have reached the ovum.