| Date | May 2017 | Marks available | 2 | Reference code | 17M.3.SL.TZ1.1 |
| Level | Standard level | Paper | Paper 3 | Time zone | Time zone 1 |
| Command term | Explain | Question number | 1 | Adapted from | N/A |
Question
Urease is an enzyme that breaks down urea into ammonia and carbon dioxide. The ammonia produced causes the pH of the solution to rise. This reaction can be followed using a pH indicator or a pH probe.
In an experiment conducted by a student the time taken for the pH indicator, thymol blue, to change from yellow to blue was recorded at different temperatures.
Outline what the standard deviations reveal about the data from this experiment.
One result in this experiment can be classified as an outlier as its value is very distant from those of the other values.
Explain an appropriate procedure for dealing with outliers.
Outline the effect of temperature on the activity of urease enzyme.
State one factor that would need to be controlled in this experiment.
Markscheme
a. standard deviation indicates the degree of variation in the data
OR
the spread of data around the mean
b. high standard deviation at 30°C «in proportion to the average» indicates less reliable data
c. low standard deviation for results from 40 to 70°C indicates more reliable data
a. outliers should not be deleted from the data set
OR
trend lines may ignore outliers>
OR
use a z-score/test
b. could be incorrectly entered or measured data
c. repeat experiment/reading/trial «for that point»
a. the reaction / activity increases with temperature
b. rate slows from 60°C to 70°C
c. fastest increase in activity is between 30°C - 40°C
d. optimum temperature is 60°C
a. concentration / volume of urea «solution»
b. concentration / volume of urease «solution»
c. concentration / volume of indicator
d. lighting conditions / background «to test tubes»
Examiners report
Syllabus sections
- 22M.1.SL.TZ2.10: Which curve shows the concentration of product during the course of an enzyme-catalysed...
-
18M.3.SL.TZ1.1c:
Evaluate the claim that, based on the data, the optimum H2O2 concentration for catalase is 70 mM.
- 21M.1.HL.TZ1.28: Which statement applies to the tertiary structure of enzymes? A. Tertiary structure is the...
- 16N.3.HL.TZ0.1b: Sketch on the graph the curve expected if the hydrolysis were performed using papain 0.5 %.
- 21M.1.HL.TZ1.30: Succinate dehydrogenase is an enzyme that catalyses the oxidation of succinic acid. If...
- 18M.2.SL.TZ2.4b: Explain enzyme–substrate specificity.
- 21M.1.SL.TZ1.14: Which statement applies to enzymes? A. Enzyme function depends on collisions between...
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17N.1.SL.TZ0.09:
Three flasks were prepared for an analysis of the activity of amylase. At time zero, each of the substances indicated in the diagrams was added.
Which flask(s) could provide support for the hypothesis that heat denatures enzymes?
A. Flasks I and II after 15 minutes
B. Flasks II and III after 15 minutes
C. Flasks I and III after 15 minutes
D. Flask III at time zero and again after 15 minutes
- 17M.3.SL.TZ1.1c: Outline the effect of temperature on the activity of urease enzyme.
- 16N.3.HL.TZ0.1c: Explain what would happen to fish protein hydrolysis if no alkali were added to the reaction...
- 18N.1.SL.TZ0.10: Living organisms control pH within their tissues. What is a reason for regulating pH? A. ...
- 18M.2.HL.TZ2.4c: Explain how enzymes catalyse chemical reactions.
- 17M.1.SL.TZ1.10: The graph shows the effect of increasing the substrate concentration on the rate of an...
- 16N.3.HL.TZ0.1a: State the effect of enzyme concentration on the hydrolysis of proteins.
- 22M.1.SL.TZ1.8: The graph shows enzyme activity plotted against temperature. What is the reason for the...
- 22M.1.HL.TZ1.5: The graph shows the activity of an enzyme at various temperatures. The pH of the experiment...
- 18N.1.HL.TZ0.8: The graph shows the effect of changing the substrate concentration on the early stages of an...
- 19M.3.HL.TZ1.1a: State the effect immobilization of lipase has on its optimum temperature.
- 19N.3.SL.TZ0.2b: Outline the measurements which would need to be taken to determine the activity of the...
- 17M.1.SL.TZ1.7: In an experiment the effect of changing pH on an enzymatic reaction is tested. Which could be...
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22M.2.SL.TZ2.5b:
In biotechnology, enzymes are used to transfer genes to bacteria. Outline how two specific enzymes are used for the transfer.
- 18M.3.SL.TZ1.1b: Identify two factors that would need to be controlled in generating these data.
- 17M.1.SL.TZ2.27: The bacterium Neisseria gonorrhoeae causes infections related to the human reproductive...
- 21M.1.HL.TZ2.29: The dashed line shows the relationship between the activity of an enzyme and the...
- 17M.3.SL.TZ1.1d: State one factor that would need to be controlled in this experiment.
- 16N.1.HL.TZ0.9: It is possible to attach β-galactosidase to alginate beads for use in the production of...
-
18M.3.SL.TZ1.1a:
Describe the relationship between increasing H2O2 concentration and catalase activity.
- 17M.1.SL.TZ1.21: Cladograms can be created by comparing DNA or protein sequences. The cladogram on the left is...
- 22M.1.HL.TZ2.29: Ethylene glycol is used as an antifreeze chemical. If a person ingests it accidentally,...
-
22M.2.HL.TZ2.7a:
Outline, using graphs, the effect of different factors that influence enzyme activity.
-
22M.2.SL.TZ2.5a:
Explain the decrease in activity of the enzyme on either side of the optimum temperature.
-
19M.1.SL.TZ2.10:
Lactose intolerance occurs when the enzyme, lactase, that digests lactose is not produced after infancy in humans. The incidence of lactose intolerance varies in different racial groups. The graph shows the distribution of lactose intolerance in different human populations.
[Source: © International Baccalaureate Organization 2019]
What can be hypothesized from the graph?
A. Native American people produce most lactase after infancy.
B. Most Indian people do not produce lactase after infancy.
C. Lactase is not produced after infancy in most Caucasian people.
D. One quarter of Afro-Caribbean people will probably experience digestive problems when drinking milk.
- 19M.3.HL.TZ1.1c: Based on these experimental results, suggest one advantage of immobilizing lipase.
- 19N.1.SL.TZ0.10: What effect do changes in pH have on enzymes? A. All enzymes increase in activity as pH...
- 19N.3.SL.TZ0.2a: State another independent variable that would affect the activity of this enzyme.
- 17M.3.SL.TZ1.1a: Outline what the standard deviations reveal about the data from this experiment.
-
16N.3.SL.TZ0.2b:
Suggest one method that could have been used to keep the tubes at a constant temperature.
-
21M.1.SL.TZ1.15:
Which enzyme is matched to its function?
-
19M.3.HL.TZ1.1b:
The graph of the effect of pH on immobilized lipase activity does not allow for the determination of optimum pH precisely. Explain how a more exact value for the optimum pH could be determined.
- 17M.2.HL.TZ1.1f.ii: Suggest a reason for the greater expression of the gene for the urea transporter after an...
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21M.2.HL.TZ2.2d.ii:
Explain what happens to an enzyme if there is a change of pH.
- 21N.1.SL.TZ0.9: Lactose can be removed from milk by passing the milk through a column of alginate beads to...
- 21M.1.HL.TZ1.8: The graph shows the progress of the same enzyme-controlled reaction at two different...
-
21M.2.SL.TZ2.3b:
State a role of the active site of an enzyme.
- 17M.2.SL.TZ1.1c: Estimate how much smaller drilled oysters raised in seawater at a high CO2 concentration were...
- 18M.2.SL.TZ2.4a: Sketch a graph to show the effect of temperature on the activity of enzymes.
- 16N.3.SL.TZ0.2a: Suggest one reason for differences between the cereal grains, in the percentage of starch...
- 16N.3.SL.TZ0.2c: Explain the importance of having equal quantities of the enzyme at the start of the experiment.
- 18M.1.SL.TZ1.10: What is the advantage of using lactase in an immobilized state in the food manufacturing...
- 16N.1.SL.TZ0.9: A fever in a normally healthy adult during an illness is not usually a problem and can be...
-
18M.2.HL.TZ1.6c:
Hydrogen bonds can exist both within and between molecules in living organisms and have an impact on their structure and function. Explain the importance of hydrogen bonding for living organisms.
