| Date | November 2016 | Marks available | 1 | Reference code | 16N.3.HL.TZ0.1 |
| Level | Higher level | Paper | Paper 3 | Time zone | TZ0 |
| Command term | State | Question number | 1 | Adapted from | N/A |
Question
The rate of hydrolysis of fish proteins using the enzymes papain and pancreatin was monitored using the apparatus shown. The pH decreased with the progress of hydrolysis, so alkali in the burette was added as necessary in order for the hydrolysis to proceed at constant pH. The rate of protein hydrolysis was measured as the amount of alkali added. Measurements were taken at constant conditions of temperature and pH for two enzyme concentrations, 1 % and 0.1 %.
State the effect of enzyme concentration on the hydrolysis of proteins.
Sketch on the graph the curve expected if the hydrolysis were performed using papain 0.5 %.
Explain what would happen to fish protein hydrolysis if no alkali were added to the reaction vessel.
Markscheme
positive correlation
OR
faster hydrolysis at higher concentration
curve with similar shape between papain 0.1 % and 1 %
Curve to start at 0.
Allow a similar/same shaped curve to papain 1 % to be anywhere within the shaded area shown on the graph.
a. hydrolysis of protein produces hydrogen ions/amino acids
b. pH decreases / increased acidity
c. causing denaturation of enzyme/pancreatin/papain
d. decrease of reaction «rate»/no hydrolysis
e. enzymes work best at the optimum pH / OWTTE
