Cambridge IGCSE Biology - 0610 - Supplement Paper 4 2018 Winter Zone 1

(a) (i) State the principal source of energy required for trophic level D of the pyramid of biomass in Fig. 1.1.
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(ii) State the letter that represents the primary consumers in Fig. 1.1.
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(iii) State how carbon is transferred from producers to primary consumers.
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(iv) Explain why trophic level A is smaller than trophic level B in the pyramid of biomass in Fig. 1.1.
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(b) Some fungi and bacteria are decomposers.
(i) Define the term decomposer.
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(ii) Arrow X on Fig. 1.1 indicates the transfer of carbon from decomposers to the atmosphere.
State the name of process X.
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(c) Describe how human activities are affecting the carbon cycle.
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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. ...............................................................[1]
(b) State and explain the evidence from Fig. 2.1 that suggests that the bacteria in dish F are resistant to penicillin. ...............................................................[2]
(c) (i) Explain how bacteria become resistant to antibiotics and how humans can reduce the problem of antibiotic resistance. ...............................................................[6]
(ii) Explain why viral infections cannot be treated with antibiotics. ...............................................................[1]
(d) Some bacteria and viruses cause disease but many are useful to the biotechnology industry. Explain why bacteria are useful in biotechnology. ...............................................................[3]

Fig. 3.1 shows a photomicrograph of a section of a root.


(a) Structure J is a xylem vessel.
The xylem vessels conduct water from the roots to the stems.
State the features of xylem vessels that enable them to conduct water.
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(b) Describe the pathway of water from outside the root to the xylem vessels (J) at the centre of the root. Use the letters in Fig. 3.1 in your answer.
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(c) Scientists wanted to determine the flow-rate of water in roots.
They measured the flow-rate in three zones of onion roots as shown in Fig. 3.2.

They measured the flow-rate in healthy roots and roots that had been treated with a toxic solution.
Their results are shown in Table 3.1.
[Table_1]
(i) Calculate the percentage increase in the average flow-rate between zone 1 and 3 for healthy roots.
Give your answer to two significant figures.
Show your working.
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(ii) The scientists observed that the xylem vessels nearer the root tip were narrower than the xylem vessels higher up the root.
Describe how the width of xylem vessels in different zones of a root affects the average flow-rate of water. Use the information in Table 3.1 in your answer.
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(iii) Suggest why there was little difference in the flow-rate in healthy roots and in roots treated with the toxic solution.
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The eye is a sense organ that responds to light. Fig. 4.1 is a diagram of a section through the human eye.

(a) Table 4.1 describes some of the functions of the parts of the eye.
Complete the table by:

• naming the parts of the eye
• using the letters on Fig. 4.1 to identify the parts of the eye.

• ^X_B – normal colour vision
• ^X_b – colour blindness.

The liver is an important organ in many processes.
(a) The liver responds to changes in insulin concentration.
Insulin is a hormone.
(i) Define the term hormone.
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(ii) Describe how the liver responds to an increase in insulin concentration.
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(b) The liver is also involved in the processing of amino acids.
(i) Describe how excess amino acids are broken down.
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(ii) State the name of the process that assembles amino acids to form proteins.
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(c) The liver is also involved in the processing of toxins.
(i) Lactic acid is an example of a toxin that is produced during vigorous exercise and processed in the liver.
Describe how lactic acid is processed.
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(ii) Alcohol is another toxin that is processed in the liver.
The effect of alcohol consumption on the risk of dying from liver disease was investigated in men and women.
The results are shown in Fig. 5.1.
[Image_1: Description of image showing a graph]
Describe the results shown in Fig. 5.1.
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(a) (i) Sucking is an example of an involuntary action observed in newborn mammals.
State the name given to involuntary actions.
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(ii) Describe the advantages of breast-feeding compared with bottle-feeding.
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(b) The digestive systems of young mammals are not fully developed.
Enzymes such as amylase, maltase and protease are often added to baby food to aid chemical digestion.

(i) Complete Table 6.1 by stating the substrate and product(s) for each enzyme reaction.
[Table_1]
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(ii) Suggest why the temperature of baby food must be controlled when the enzymes are added.
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(iii) State one other condition that must also be controlled to optimise enzyme activity.
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