5 marksMatch up the key terms to their definition.
Enzyme |
| Groove in enzyme where the reaction take place |
Substrate | Molecules that bind to an enzyme | |
Catalyst | One enzyme for one substrate | |
Specificity | Any molecule that speeds up reactions | |
Active site | A protein that speeds up reactions |
1 markDefine what is meant by the term enzyme-substrate complex.
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1 markFig. 1 shows a model of how an enzyme works.
Fig. 1
Label the enzyme molecule on Fig. 1.
3 marksEnzymes are biological catalysts.
(i) Explain what is meant by the term catalyst.
[2]
(ii) State why enzymes are important in organisms.
[1]
1 markSketch in the appearance of an enzyme-substrate complex on the diagram in Fig. 2.
The diagram is provided again here for you.
Fig. 2
4 marksDescribe the action of enzymes.
Use the following words as part of your answer:
collide complementary randomly recycled
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1 markFig. 1 represents the reactants and products in a chemical reaction and four different enzymes (A, B, C or D).
Fig. 1
State the letter of the enzyme responsible for this reaction.
2 marksState what happens when a substrate with a shape that is not complementary to the enzyme tries to enter the active site.
2 marksA student investigated the effect of enzyme concentration on the mass of product formed in one hour.
Fig. 2 shows the results of this investigation.
concentration of enzyme / arbitrary units | mass of product formed / grams |
5 | 15 |
10 | 22 |
15 | 25 |
20 | 32 |
25 | 38 |
30 | 40 |
35 | 40 |
40 | 40 |
Fig. 2
Complete the graph by plotting the points and drawing a line to show the trend in the data. The first three points have been plotted for you.
2 marksUsing the data from part (c) describe the effect that enzyme concentration has on the mass of product formed.
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4 marksThe pancreas is an organ that produces enzymes used in digestion.
Explain the importance of enzyme specificity in the digestion of food.
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3 marksEnzymes are involved in controlling cell division. Fig. 1 shows how cell division can be accelerated by two enzymes, enzymes X and Y, in cancerous liver cells. Most cancer cells produce both enzymes X and Y.
Cancer cells are likely to develop into cancerous tumours inside the liver by uncontrolled cell division.
Fig. 1
Some people carry a genetic mutation that inhibits enzyme X. A drug company has produced a medicine that inhibits enzyme Y. This medicine has been trialled in people who have the mutation and liver cancer. The medicine has been found to be successful at treating liver cancer.
Explain why.
2 marksExplain why the medicine could not be used to treat liver cancer in a patient that does not have the genetic mutation.
4 marksGlutaminase is another enzyme that has shown success in treating cancer. It is within a group of enzymes called amino acid deprivation enzymes which act on and destroy specific amino acids in cancerous cells.
Explain the action of the glutaminase on amino acids in cancer cells.
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