| Date | May 2011 | Marks available | 1 | Reference code | 11M.3.SL.TZ2.16 |
| Level | Standard level | Paper | Paper 3 | Time zone | Time zone 2 |
| Command term | Identify | Question number | 16 | Adapted from | N/A |
Question
Fungi of the genus Botryosphaeria have been found to produce certain oxidizing enzymes, laccases, that are effective in treating contaminated water and soils. Studies were undertaken to test the effects of veratryl alcohol concentrations and fermentation time in order to optimize the industrial production of laccases. Statistical analysis of the data was used to develop the graph below.
Identify the amount of laccases produced when the veratryl alcohol concentration is at its highest level and the fermentation time is at its shortest.
Identify the amount of laccases produced when the veratryl alcohol concentration is at its lowest level and the fermentation time is at its longest.
Analyse the overall effects of the veratryl alcohol concentration and fermentation time on the production of laccases.
Deduce from the graph the optimal conditions for maximizing the biotechnological production of laccases.
Markscheme
1.6 (units) cm–3 (accept answers in the range of 1.5 units cm–3 and 1.7 units cm–3)
8.3 (units) cm–3 (accept answers in the range of 8.2 units cm–3 and 8.4 units cm–3)
as fermentation time increases laccase production rises then falls; (accept converse)
as veratryl alcohol concentration increases laccase production rises then falls; (accept converse)
optimum fermentation time is 4.75/5.0/5.25 days; (accept converse)
most laccase overall with low veratryl alcohol concentration and long fermentation; (accept converse)
optimum veratryl alcohol concentration is 33/34/35 mmol dm–3;
fermentation time has greater effect than veratryl alcohol concentration;
the best time for fermentation appears to be 4.75 days; (allow 4.75 to 5.25 days)
with a veratryl alcohol concentration of 33 mmol dm–3 / moderate veratryl alcohol concentration; (allow 33 to 35 mmol dm–3)
Examiners report
F1 (a) was challenging for candidates as they appeared to find the data was very difficult to interpret, though candidates were only required to interpret it in two dimensions. Despite the small numbers taking this option, there were more complaints from teachers about this part of the exam than any other.
F1 (a) was challenging for candidates as they appeared to find the data was very difficult to interpret, though candidates were only required to interpret it in two dimensions. Despite the small numbers taking this option, there were more complaints from teachers about this part of the exam than any other.
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