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B2: Quiz 3 – Answers
B2: Quiz 3 – Answers
1) Temperature & pH
2) A graph with a peak around 37°C – like what is shown below
2) A graph with a peak around 37°C – like what is shown below
3)
a)
i) 7
ii) 0-6
iii) 8-14
b) A graph with a peak at a pH of 7 – like what is shown below
4) The substrate fits into the active site of the enzyme. The reaction takes place. The products are then released, and the enzyme is free to catalyse another reaction.
5)
a) The rate of reaction increases as the temperature rises from 10°C to 37°C because the increase in temperature gives the substrates and enzymes more kinetic energy. This means that they move around faster, which leads to more frequent collisions between the enzymes and substrates. More frequent collisions means that there will be a greater rate of reaction as the temperature increases from 10°C to 37°C
b) When the temperature goes above 37°C, the high temperature causes the bonds in the enzyme to break – the enzyme denatures. Denaturing changes the shape of the active sites of the enzymes, which means that the substrates can no longer fit into the active sites of the enzymes and therefore won’t react; this results in the rate of reaction decreasing as temperatures go above 37°C
6)
a) As the pH decreases from a pH of 7, the pH interferes with the bonds in the enzymes, which changes the shape of the active site, thus meaning that the substrates can no longer fit into the active sites of the enzymes, which results in the rate of reaction falling. The pH decreasing from 7 causes the enzymes to denature
b) As the pH increases from a pH of 7, the pH interferes with the bonds in the enzyme, which changes the shape of the active site, thus meaning that the substrates can no longer fit into the active sites of the enzymes, which results in the rate of reaction falling. The pH increasing from 7 causes the enzymes to denature
7) The stomach is very acidic. Therefore, you would expect the optimal pH for the enzyme found in the stomach to be more acidic than the optimal pH for the enzyme found in the mouth. Acids have pHs between 0 and 6 – values closer to 0 are more acidic. Enzyme A has an optimal pH of 2, which is very acidic (enzyme B has an optimal pH of around 7). Therefore, enzyme A is probably the enzyme that is found in the stomach
4) The substrate fits into the active site of the enzyme. The reaction takes place. The products are then released, and the enzyme is free to catalyse another reaction.
5)
a) The rate of reaction increases as the temperature rises from 10°C to 37°C because the increase in temperature gives the substrates and enzymes more kinetic energy. This means that they move around faster, which leads to more frequent collisions between the enzymes and substrates. More frequent collisions means that there will be a greater rate of reaction as the temperature increases from 10°C to 37°C
b) When the temperature goes above 37°C, the high temperature causes the bonds in the enzyme to break – the enzyme denatures. Denaturing changes the shape of the active sites of the enzymes, which means that the substrates can no longer fit into the active sites of the enzymes and therefore won’t react; this results in the rate of reaction decreasing as temperatures go above 37°C
6)
a) As the pH decreases from a pH of 7, the pH interferes with the bonds in the enzymes, which changes the shape of the active site, thus meaning that the substrates can no longer fit into the active sites of the enzymes, which results in the rate of reaction falling. The pH decreasing from 7 causes the enzymes to denature
b) As the pH increases from a pH of 7, the pH interferes with the bonds in the enzyme, which changes the shape of the active site, thus meaning that the substrates can no longer fit into the active sites of the enzymes, which results in the rate of reaction falling. The pH increasing from 7 causes the enzymes to denature
7) The stomach is very acidic. Therefore, you would expect the optimal pH for the enzyme found in the stomach to be more acidic than the optimal pH for the enzyme found in the mouth. Acids have pHs between 0 and 6 – values closer to 0 are more acidic. Enzyme A has an optimal pH of 2, which is very acidic (enzyme B has an optimal pH of around 7). Therefore, enzyme A is probably the enzyme that is found in the stomach
Questions
Try not to use the later questions to help you answer the earlier questions.
1) What are the two factors that affect the rate of reaction for enzymes?
2) Use the graph below to show how the rate of reaction for a normal human enzyme changes as temperature increases.
Try not to use the later questions to help you answer the earlier questions.
1) What are the two factors that affect the rate of reaction for enzymes?
2) Use the graph below to show how the rate of reaction for a normal human enzyme changes as temperature increases.
3) pH goes from 0 to 14.
a)
i) What is the pH for neutral?
ii) What is the pH for acids?
iii) What is the pH for alkalis?
b) Use the graph below to show how the rate of reaction for a normal human enzyme changes as pH increases.
4) Describe how an enzyme works/ describe the lock and key theory.
5) The graph below shows how the rate of reaction of an enzyme changes with temperature.
a) Explain why the rate of reaction for the enzyme increases as the temperature increases from 10°C to 37°C.
b) Explain why the rate of reaction for the enzyme decreases as the temperature goes above 37°C.
6) The graph below shows how the rate of reaction of an enzyme changes with pH.
b) Explain why the rate of reaction for the enzyme decreases as the temperature goes above 37°C.
6) The graph below shows how the rate of reaction of an enzyme changes with pH.
a) Why does the rate of reaction for the enzyme decrease when the pH decreases from 7?
b) Why does the rate of reaction for the enzyme decrease when the pH increases from 7?
7) The graph below shows how the pH affects the rate of reaction for 2 different enzymes; enzyme A and enzyme B.
b) Why does the rate of reaction for the enzyme decrease when the pH increases from 7?
7) The graph below shows how the pH affects the rate of reaction for 2 different enzymes; enzyme A and enzyme B.
One of these enzymes is found in the mouth, and the other is found in the stomach.
By looking at the above graph, which enzyme do you think is found in the stomach? Explain your answer.
By looking at the above graph, which enzyme do you think is found in the stomach? Explain your answer.