Question 21M.2.HL.TZ2.b
| Date | May 2021 | Marks available | [Maximum mark: 4] | Reference code | 21M.2.HL.TZ2.b |
| Level | HL | Paper | 2 | Time zone | TZ2 |
| Command term | Outline | Question number | b | Adapted from | N/A |
Outline how sperm are produced from diploid cells in the testis and how this production can be sustained over many decades of adult life.
[4]
a. germinal epithelium divide endlessly (by mitosis giving rise to spermatagonia)
b. spermatogonia are diploid/2n ✔
c. spermatogonia divide by mitosis / provide a continuous supply throughout adult life ✔
d. (some) spermatogonia enlarge forming primary spermatocytes ✔
e. primary spermatocytes undergo the first division of meiosis/meiosis I ✔
f. secondary spermatocytes produced are haploid/n ✔
g. secondary spermatocytes undergo the second division of meiosis (to produce spermatids) ✔
h. spermatids develop tails
OR
spermatids differentiate into spermatozoa / spermatids associate with Sertoli cells ✔
Marks can be awarded to an annotated diagram.
Do not accept sperm or spermatozoa as equivalent to spermatagonia or spermatocytes.
Although many candidates performed very well, many answers were vague and simply stated that sperm cells were made by meiosis without any further details. Commonly, the stages where meiosis occurs and where mitosis occurs were muddled as well as whether primary or secondary spermatocytes were diploid or haploid. The terms spermatozoa and spermatids were commonly used interchangeably.
