iGCSE Biology (0610)-20.1 Food supply - iGCSE Style Questions Paper 3

Question

(a) Humans have developed modern farming methods to increase food production.
Explain how the use of herbicides and chemical fertilisers has increased food production.

(b) Fig. 8.1 shows intensive farming of chickens.

State three disadvantages of intensive livestock production.

The protein pectinase is used in food industries to make fruit juice clear.

(d) Fig. 8.2 shows the process used to produce clear fruit juice.

(i) Explain why a temperature of 30 °C is used in step 4.
(ii) During step 4 amylase may be added to the fruit juice.
Suggest the purpose of adding amylase.
(iii) Explain why the juice is heated to a high temperature in step 5.

(e) Yeast is used in biotechnology.
Circle two uses of the products of anaerobic respiration in yeast.

biofuelsinsulin productionbread‑makingherbicide productionlactic acid productionwashing powders

▶️ Answer/Explanation

Solution

(a) Herbicides kill weeds, reducing competition for crops, while chemical fertilisers provide essential nutrients (e.g., nitrates for amino acids, magnesium for chlorophyll), enhancing plant growth and yield.

(b) Three disadvantages: (1) Poor animal welfare due to overcrowding, (2) High disease risk, (3) Increased antibiotic resistance or environmental pollution.

(c) Pectinase is an enzyme (biological catalyst).

(d)(i) 30°C is the optimum temperature for enzyme activity.
(ii) Amylase breaks down starch, increasing sweetness/clarity.
(iii) Heating kills pathogens (pasteurisation).

(e) Circled uses: biofuels and bread-making (products of anaerobic respiration in yeast are ethanol and CO₂).

Question

Dairy cattle are kept for milk production. Approximately half of all the calves born are male.
(a) Sex is determined in cattle in exactly the same way as it is in humans.
Explain why 50% of all cattle are born male.
You may draw a genetic diagram to help your explanation.

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(b) Dairy farmers only need a very small number of male calves. They limit the number by
using sex selection. Sperm cells are identified and sorted before they are used in artificial
insemination (AI).
Explain how artificial insemination is carried out.
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(c) Table 2.1 shows the composition of 100 g of cow’s milk compared with the same quantities of
commercial formula milk and human milk.

Some women do not breast-feed their babies but bottle-feed them using formula milk. Health
authorities advise against the use of cow’s milk until babies are about 9 months old.
Use the information in Table 2.1 to explain the advantages of using formula milk rather than
cow’s milk.
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One of the components of human milk is the enzyme lysozyme that is present in many body fluids
and is responsible for breaking down the cell walls of bacteria.
(d) Define the term enzyme.
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(e) The effect of human lysozyme on two common species of bacteria, A and B, was investigated
at two different values of pH.
The investigation was set up as shown in Fig. 2.1.
The test-tubes were kept at 37 °C for 24 hours.

After 24 hours, samples were taken from each test-tube. Each sample was placed onto
nutrient agar in Petri dishes. The dishes were incubated at 28 °C for a further 24 hours to
allow any bacteria to grow.
The results are shown in Fig. 2.2.

Explain the results shown in Fig. 2.2 by comparing the following pairs:
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(f) Human milk also contains antibodies. Explain the benefits of antibodies to a newborn child.
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Answer/Explanation

Ans:

iGCSE Biology (0610)-20.1 Food supply – iGCSE Style Questions Paper 3

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