Question 18M.3.SL.TZ2.b.ii
| Date | May 2018 | Marks available | [Maximum mark: 2] | Reference code | 18M.3.SL.TZ2.b.ii |
| Level | SL | Paper | 3 | Time zone | TZ2 |
| Command term | Describe | Question number | b.ii | Adapted from | N/A |
In the generator method of ethanoic acid fermentation, Acetobacter aceti are grown over wood shavings in a fermenter to the point where they form a biofilm.
At the base of the fermenter oxygen is bubbled in, which then rises through the wood shavings. Ethanol drips through the wood shavings. At a suitable temperature the ethanol is converted to ethanoic acid, which is withdrawn from the bottom of the fermenter, and new ethanol is added at the top.
Describe one way in which microorganisms in this fermenter could be limited by their own activities.
[2]
a. name of a factor
b. description
eg
a. pH
b.lowered by «ethanoic» acid production.
eg
a. increase in temperature
b. due to metabolism.
eg
a. increased population size/reproduction
b. would limit resources.
eg
a. increased metabolic waste
b. reduce population.
