| Date | November 2017 | Marks available | 3 | Reference code | 17N.3.HL.TZ0.12 |
| Level | Higher level | Paper | Paper 3 | Time zone | TZ0 / no time zone |
| Command term | Describe | Question number | 12 | Adapted from | N/A |
Question
Beans contribute to flatulence. Alpha-galactosidase, derived from the fungus Aspergillus niger, is an enzyme that breaks down the fibre usually fermented by bacteria, reducing intestinal gas. Describe how alpha-galactosidase would be produced using A. niger in a continuous fermenter.
Temperature is a variable that needs to be continually monitored in deep-tank batch fermentation of penicillin. List two other variables that need to be monitored.
Markscheme
a. constant nutrient medium «supply» needed/maintained
b. optimal mixing
c. fermented in sterile bioreactor
d. alpha-galactosidase production/general conditions assayed/screened/monitored «throughout the process»
e. continuous removal of alpha-galactosidase/products
[Max 3 Marks]
a. pH
b. «dissolved» oxygen
