iGCSE Biology (0610)-21.2 Biotechnology – iGCSE Style Questions Paper 4

Question

Microbiologists test strains of bacteria for antibiotic resistance.
     They do this by soaking paper discs in antibiotics and placing them on bacteria growing in Petri
     dishes.
     The paper discs in the centre of Petri dishes E and F in Fig. 2.1 have been soaked in penicillin.

     

(a) State the type of microorganism that produces penicillin.
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(b) State and explain the evidence from Fig. 2.1 that suggests that the bacteria in dish F are
        resistant to penicillin.
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(c) (i) Explain how bacteria become resistant to antibiotics and how humans can reduce the
             problem of antibiotic resistance.
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      (ii) Explain why viral infections cannot be treated with antibiotics.
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(d) Some bacteria and viruses cause disease but many are useful to the biotechnology industry.
        Explain why bacteria are useful in biotechnology.
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Answer/Explanation

Ans:

Question

Bacteria are used in many biotechnological processes.
(a) Explain why bacteria are useful in biotechnology.
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(b) Insulin is one of many human proteins that are made by genetically engineered bacteria.
Some people cannot produce insulin because their immune system has destroyed the cells
that make insulin.
(i) State the organ that contains the cells that have been destroyed.
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(ii) State the name of the disease caused by the destruction of these cells.
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(iii) State the function of insulin in the body.
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(c) Genetically engineered bacteria that are used to make insulin were grown in a fermenter for
five days.
Samples were taken from the fermenter every six hours and the number of bacteria in 1.0 mm3
of the nutrient solution were counted.
Changes in the numbers of living bacteria in the samples taken from the fermenter are shown
in Fig. 3.1.

(i) Complete Fig. 3.1 by adding labels for the axes at 1 and 2 .
(ii) State the names of the stages of population growth of the bacteria labelled P to S.
P ……………………………………………………………………………………………………………………….
Q ………………………………………………………………………………………………………………………
R ……………………………………………………………………………………………………………………….
S ……………………………………………………………………………………………………………………….
(iii) Explain, with reference to Fig. 3.1, why the bacteria did not grow in the fermenter for
longer than five days.
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(d) Mineral salts are important in the human diet. One of the most important is iron.
Explain:
• the importance of iron in the human diet
• the effects of an iron deficiency.
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(e) Fig. 3.2 shows a field of cassava, Manihot esculenta, which is a crop plant grown in parts of
Africa and Asia.

The plants store starch in their roots, which form a large part of the diet for many people.
Cassava does not provide many vitamins or mineral ions.
Genetic engineers have modified cassava to increase its iron content. They have done this
by incorporating a gene for a membrane protein from the plant Arabidopsis thaliana.
(i) State the name of the enzyme that is used to cut out the gene from the DNA of
A. thaliana.
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(ii) Describe how the gene from A. thaliana and the DNA from cassava form recombinant

DNA.
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(iii) Scientists who develop genetically engineered varieties of crop plants often breed them
for several generations before releasing them for farmers to use.
Suggest why the scientists do this.

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Answer/Explanation

Ans:

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