Enzyme Action (Cambridge O Level Biology)

Exam Questions

44 mins14 questions
1a
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5 marks

Match 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

1b
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1 mark
Define what is meant by the term enzyme-substrate complex.

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2a
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1 mark

Fig. 1 shows a model of how an enzyme works.

vIPj2yJ4_image

Fig. 1

Label the enzyme molecule on Fig. 1.

2b
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3 marks

Enzymes are biological catalysts.

(i)

Explain what is meant by the term catalyst.

[2]

(ii)

State why enzymes are important in organisms.

[1]
2c
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1 mark

Sketch in the appearance of an enzyme-substrate complex on the diagram in Fig. 2.

The diagram is provided again here for you. 

vIPj2yJ4_image

Fig. 2

2d
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4 marks

Describe the action of enzymes.

Use the following words as part of your answer:

collide     complementary     randomly     recycled

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3a
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1 mark

Fig. 1 represents the reactants and products in a chemical reaction and four different enzymes (A, B, C or D).

2d

Fig. 1

State the letter of the enzyme responsible for this reaction. 

3b
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2 marks

State what happens when a substrate with a shape that is not complementary to the enzyme tries to enter the active site.

3c
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2 marks
A 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.

q5a-1bio-1f-june18-qp-gcse-bio

3d
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2 marks

Using the data from part (c) describe the effect that enzyme concentration has on the mass of product formed.

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1
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4 marks

The 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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2a
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3 marks

Enzymes 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. cOODGpwn_cancer-cells

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. 

2b
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2 marks

Explain why the medicine could not be used to treat liver cancer in a patient that does not have the genetic mutation.

2c
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4 marks

Glutaminase 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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