Fertilization and implantation
Read the following passage carefully and answer the given questions.
During copulation semen is released by the penis into the vagina. The motile sperms swim rapidly, pass through the cervix, enter into the uterus and finally reach the ampullary region of the fallopian tube. The ovum released by the ovary is also transported to the ampullary region where fertilisation takes place. During fertilization, a sperm comes in contact with the zona pellucida layer of the ovum and induces changes in the membrane that block the entry of additional sperms. This induces the completion of the meiotic division of the secondary oocyte. The second meiotic division is also unequal and results in the formation of a second polar body and a haploid ovum (ootid). Soon the haploid nucleus of the sperms and that of the ovum fuse together to form a diploid zygote. The zygote undergoes cleavage and forms a blastocyst, which gets implanted in the endometrium of the uterus after about 6-7 days of fertilization. Successful fertilization leads to pregnancy.
The human male ejaculates about __________ sperms during a coitus.
Answer & explanation
Correct answer: option 2
The correct answer is Option (2) → 200 to 300 million
A human male releases about 200 to 300 million sperms in one ejaculation during coitus. For normal fertility, at least 60 per cent of them must have normal shape and size, and at least 40 per cent must be vigorously motile.
Note: The passage is taken from NCERT. NTA has put lines of the NCERT text together to make it. Most CUET (UG) questions come straight from NCERT, so study the book line by line, including figures and their titles.
NCERT Extract:
Gametogenesis – …
