Biotechnology & Genetic Modification (Cambridge (CIE) IGCSE Biology)

Fig. 1 shows a field of sugar cane and the remains of the sugar cane after the harvest.

Fig. 1

The sugars in sugar cane can be used to make ethanol biofuel.

(i)

State the name of an organism that can be used to make ethanol biofuel from sugars.

[1]

(ii)

State the process that this organism uses to make ethanol biofuel from sugars.

[2]

A lot of heat is needed for the final stage of making the biofuel. This heat can be provided by burning fossil fuels.

Explain why it would be better to burn the remains of the sugar cane instead of burning a fossil fuel.

Bacteria are useful in biotechnology and genetic engineering.

Fig. 1 shows a photomicrograph of a bacterium. 

Fig. 1

State the name of the process that is taking place in Fig. 1. 

Extended Only

(i)

Write the formula that would be used to calculate the actual width of the bacterium.

[1]

(ii)

The actual width of the bacterium is 0.0008 mm.

Convert this value to micrometres (μm).

[1]

Extended Only

Genetically modified bacteria can produce human insulin. 

(i)

State the name of the disease that can be treated with insulin injections.

[1]

(ii)     

Insulin is a protein.

Describe the process of using bacteria in genetic engineering to produce human proteins.

[5]

Extended Only

Genetically modified bacteria are often grown in fermenters.

(i)

Suggest why steam is used to clean fermenters.

[2]

(ii)

 State three conditions inside a fermenter that are measured and controlled.

[3]

(iii)

State the name of one commercial product, other than insulin, that is made in fermenters.

[1]

Extended Only

Crop plants can also be genetically modified. 

Describe the advantages of genetically modifying crops.

A factory uses biotechnology to process apples.

Some of the apple juice is mixed with yeast and used to make ethanol.

(i)     

State the type of respiration in yeast that produces ethanol.

[1]

(ii)

State the name of the substance in apple juice that is converted to ethanol by yeast.

[1]

The yeast uses enzymes to produce ethanol.

(i)

Define the term enzyme.

[2]

(ii)

Fig. 1 shows apparatus used to find the best (optimum) temperature for making ethanol.

Fig. 1

The same apparatus was used at different temperatures.

The rate of ethanol production was compared by counting the number of bubbles of gas produced by the yeast and                  apple juice mixture per minute.

 State the name of the gas produced by the yeast in Fig. 1.

(iii)

The results of the investigation are shown in Fig. 2.

Fig. 2

Calculate the increase in the rate of reaction from 20 °C to 25 °C in Fig. 2.

Give your answer in bubbles per minute.

[1]

(iv)

State the optimum temperature for the reaction shown in Fig. 2.

Give your answer in °C.

[1]

The cut surface of an apple usually turns brown when exposed to air. This is caused by enzymes.

Three slices of apple were given different treatments and were then exposed to air for 30 minutes.

Table 1 shows the treatments and appearance of the apple slices.

Table 1

Suggest why slice B and slice C did not turn brown after 30 minutes.

The enzyme pectinase is used in industry for the production of apple juice.

Explain why pectinase is used when making apple juice.

Hygienic conditions are required in an apple juice factory.

Describe three precautions workers should take to ensure that good food hygiene is maintained in the apple juice factory.

Extended Only

Penicillin is an antibiotic produced by the fungus Penicillium chrysogenum.

Fig. 1 shows the process used to produce penicillin.

Fig. 1

Explain why there is a water jacket around the fermenter and why acids or alkalis are added to the fermenter.

Extended Only

Fig. 2 shows the mass of fungus and the yield of penicillin during the fermentation process.

Fig. 2

(i)

State the time interval over which the fungus grew at its maximum rate.

Give your answer in hours. 

[1]

(ii)

As the fungus grows in the fermenter, the nuclei in the fungal hyphae divide.

State the type of nuclear division that occurs during the growth of the fungus in the fermenter.

[1]

(iii)

Explain why the growth of the fungus slows down and stops.

[3]

Extended Only

Penicillin is not needed for the growth of P. chrysogenum.

(i)

State the evidence from Fig. 2 that shows that penicillin is not needed for this growth.

[2]

(ii)

The people in charge of the penicillin production emptied the fermenter after 160 hours.

Use the information in Fig. 2 to suggest why they did not allow the fermentation to continue for longer.

[1]

Extended Only

Downstream processing refers to all the processes that occur to the contents of the fermenter after it is emptied. This involves making penicillin into a form that can be used as a medicine.

Suggest why downstream processing is necessary.

Explain why antibiotics, such as penicillin, affect bacteria but not viruses.

Tissue plasminogen activators (TPAs) are human proteins that are used as drugs to break down blood clots.

TPAs break down blood clots by activating plasminogen. Plasminogen is a protein that is always present in the blood.

When activated, plasminogen forms a protease that breaks down fibrin molecules.

(i)

Plasminogen is found in the plasma.

State what is meant by the term plasma.

[1]

(ii)

State the products of the action of protease on the protein fibrin.

[1]

Extended Only

TPAs can be produced by genetically-engineered bacteria.

Fig. 1 shows some of the stages involved in genetically engineering a bacterium to make a TPA.

Fig. 1

(i)

State the name of structure A in Fig. 1.

[1]

(ii)

In the flow chart, X represents the action of an enzyme on a molecule of DNA.

State the name of this enzyme.

[1]

(iii)

The TPA gene is inserted into structure A.

Explain how the gene is inserted into structure A to form structure B as shown in Fig. 1.

[3]

(iv)

Before TPA was made by genetically-engineered bacteria it was only available from blood donated by people.

Suggest one advantage of producing TPA by genetically-engineered bacteria.

[1]

(v)

The genetically-engineered bacteria produce mRNA that is a copy of the human TPA gene.

Explain the role of mRNA in the bacterium.

[2]

Extended only

Bacteria are often used in biotechnology as there are several advantages to their use in this field.

Outline the benefits of using bacteria in biotechnology.

Another example of a microorganism that is useful in biotechnology is the fungus Aspergillus niger. They typically grow on fruit and produce pectinase that breaks down plant cell walls. This enables A. niger to feed on the contents of the plant cells.

Pectinase is also used in the food and beverage industry.

Explain the use of pectinase in the food and beverage industry.

Extended only

Many fruits, such as lemons and limes, contain a substance called citric acid which has a wide variety of applications in the food-, cosmetics- and pharmaceutical industries.

Certain strains of A. niger can be used to produce citric acid on an industrial scale by the aerobic breakdown of glucose at pH levels of between 4 and 6.5. The fungus is cultured in large industrial fermenters where conditions are kept at an optimum.

Describe and explain the conditions that should be controlled in the fermenter to ensure optimum production of citric acid.

Extended only

In the 1970s, the major US agrochemical business Monsanto developed a family of chemical herbicides that it sold under the trade name Roundup™. 

Roundup™ is active against a very wide variety of plants.

Monsanto also developed a range of genetically-modified crop seeds that were resistant to Roundup™ by inserting a gene from a species of soil bacterium.

Suggest two possible ecological risks of planting these genetically-modified seeds.