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Practice each question, then open the answer or worked solution.
What is the difference between a primary oocyte and a secondary oocyte?
Ans: The difference is as given below:
Feature | Primary oocyte | Secondary oocyte |
Formation time | Intra-uterine i.e., when the female is still a fetus. | At the beginning of puberty or each menstrual cycle |
Surrounding structures | Secondary follicles | Tertiary follicles |
Ploidy | Diploid with two sets of chromosomes | Haploid with one set of chromosomes |
What is the significance of ampullary–isthmic junction in the female reproductive tract?
Ans: At the junction of ampulla and isthmus, the parts of a fallopian tube or an oviduct, the ovum is located when a sperm can come and fertilize it i.e., it is the primary site of fertilization in an ideal scenario of fertilization. It is at this junction that the sperm nucleus and ovum are united to form a zygote and the zygote travels a predetermined path to the uterus for implantation within the required time.
How does zona pellucida of ovum help in preventing polyspermy?
Ans: The moment one spermatozoan comes into contact with the ovum or the egg, the zona pellucida undergoes some cortical changes which makes this layer impenetrable for other sperms. Thus, no more than one sperm can fertilize the ovum i.e., polyspermy is prevented.
Mention the importance of LH surge during menstrual cycle.
Ans: The LH surge in the menstrual cycle has an extremely important role and is essential for a fully functioning menstrual cycle in a female. The LH surge occurs around mid of the menstrual cycle i.e., on the 14th day and causes the rupture of graafian follicle due to which the secondary oocyte is released from the ovary causing ovulation.
Which type of cell division forms spermatids from the secondary spermatocytes?
Ans: The type of cell division during which the secondary spermatocytes from spermatids is the reduction division or meiosis in which the chromosome number is halved leading to production of haploid gametes.