DP Biology (last assessment 2024)
Question 19N.3.HL.TZ0.d
| Date | November 2019 | Marks available | [Maximum mark: 2] | Reference code | 19N.3.HL.TZ0.d |
| Level | HL | Paper | 3 | Time zone | TZ0 |
| Command term | Explain | Question number | d | Adapted from | N/A |
d.
[Maximum mark: 2]
19N.3.HL.TZ0.d
The diagram below represents a small-scale biogas fermenter.
[Source: © Science in Society. http://www.i-sis.org.uk/BiogasChina.php]
Explain how conditions in the fermenters are maintained to maximize penicillin production.
[2]
Markscheme
a. aerobic conditions achieved by stirring/aeration ✔
b. buffers maintain pH ✔
c. moderate temperatures maintained by cooling jacket ✔ Accept mention of 20-30°C.
d. product is collected during stationary phase ✔
Award marks for identification of the factor and description of the effect.
