Question

How many sperm and ova will be produced from 25 primary spermatocytes and 25 primary oocytes respectively?
a. 100 sperm and 50 ova
b. 50 sperm and 25 ova
c. 100 sperm and 100 ova
d. 100 sperm and 25 ova

Answer 1

Hint: Spermatogenesis is the process by which haploid spermatozoa is produced, first the mitotic division occurs and results in the formation of the primary spermatocyte and later spermatids are formed by the mitotic division and finally form the spermatozoa and it is different in the case of oocytes.

Complete answer:
- In the process of spermatogenesis, first, the primary spermatocyte is formed, it is diploid in nature and has 46 chromosomes.
- These primary spermatocytes undergo the first meiotic division or meiosis I then it produces the two secondary spermatocytes.
- Later each secondary spermatocyte produced by meiosis I undergo division again through the second meiosis or meiosis II and form the two spermatids.
- Later these spermatids are converted to spermatozoa.
- So from each secondary spermatocytes, 2 spermatids are formed which means total four spermatids will be formed.
- So from the one primary spermatocyte totally 4 spermatozoa are formed. Later the sperm produced is released by a process called spermitation.
- In the case of oogenesis, first primary meiosis occurs and forms the primary oogonium, later by the meiosis II ovum is formed and polar bodies are also formed.
- So from one oogonium, only one ovum is formed.
- In the above question, they asked for 25 primary spermatocytes, we already know that from one primary spermatocyte produces 4 sperm, so from 25, it is 25×4 which are 100 sperms.
- When coming to ovum they asked for 25 primary oocytes, we already know that each primary oocyte produces a single ovum so it is 25 only.

Hence, The correct answer is option (D).

Note: One should understand at which stage the mitotic and meiosis divisions take place, so that it can easily remember how many daughter cells are produced, if this common point is clear, one can calculate the sperm and ovum production calculations, very easily.