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3. Succinate is converted to fumarate by a dehydrogenase enzyme as shown - Scottish Highers Human Biology - Question 3 - 2023
Question 3
3. Succinate is converted to fumarate by a dehydrogenase enzyme as shown. succinate → fumarate + hydrogen succinate dehydrogenase The rate... show full transcript
Worked Solution & Example Answer:3. Succinate is converted to fumarate by a dehydrogenase enzyme as shown - Scottish Highers Human Biology - Question 3 - 2023
Step 1
State one variable, other than those mentioned, that would need to be controlled for a valid conclusion to be drawn.
Answer
One variable that needs to be controlled is the temperature of the solution/test tubes. Keeping the temperature constant ensures that any changes in the rate of reaction can be attributed solely to the concentration of succinate and the presence of the inhibitor.
Step 2
Describe one possible source of error when using DCPIP in this investigation.
Answer
A possible source of error is the difficulty in ensuring that all drops of DCPIP are consistent in volume. Inconsistent volumes can lead to varying amounts of DCPIP in each test tube, affecting the accuracy of the decolourisation measurements.
Step 3
Suggest how the reliability of the results in this investigation could be improved.
Answer
To improve reliability, the investigation could be repeated multiple times at each concentration of succinate, and an average time to decolourise DCPIP could be calculated. This reduces the impact of any outliers due to random error.
Step 4
Draw a line graph to show the results of the investigation with inhibitor.
Answer
To draw the line graph, plot the concentration of succinate on the x-axis and the time to decolourise DCPIP on the y-axis for the 'With inhibitor' data. Ensure to label both axes correctly and mark the points for each concentration before connecting them with a line.
Step 5
Describe how the results show that the inhibitor used is a competitive inhibitor of succinate dehydrogenase.
Answer
The results show that as the concentration of succinate increases, the time taken to decolourise DCPIP decreases even in the presence of the inhibitor. This indicates that higher substrate concentrations can overcome the inhibition, characteristic of competitive inhibitors.
Step 6
Step 7
Describe the role of dehydrogenase enzymes in the citric acid cycle.
Answer
Dehydrogenase enzymes play a crucial role in the citric acid cycle by catalyzing the removal of hydrogen ions and electrons from substrate molecules. This process is essential for the subsequent production of NADH and FADH2, which are used in the electron transport chain for ATP production.
Step 8