Cambridge IGCSE Biology - 0610 - Supplement Paper 4 2011 Winter Zone 2

Heart surgeons may stop the heart beating during operations. While this happens blood is pumped through a heart-lung machine that oxygenates the blood.
Fig. 1.1 is a diagram showing a heart-lung machine in use.

(a) Name the structures labelled A to D.
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(b) Name the blood vessels E and F.
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(c) The heart-lung machine is used so that surgeons can operate on the arteries supplying heart muscle. These arteries may be diseased.
Name these arteries and explain how they may become diseased.
name of arteries ................................................................
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(d) Suggest why a patient is put on a heart-lung machine during such an operation.
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Humans have a double circulation system. There is a low pressure circulation and a high pressure circulation.
(e) Explain how the structure of the heart enables it to pump blood into two circulations at different pressures.
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(a) Movement is a characteristic of living organisms.
Define the term *movement*.
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When the hand is stimulated by a hot object a reflex action occurs in which the fore-arm is raised.
Fig. 2.1 shows the muscles and the neurones involved in the reflex action.
The arrows show where there are nerve impulses during the reflex action.

(b) (i) State the name for the action of two opposing muscles, such as the biceps and the triceps.
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(ii) Explain how two opposing muscles bring about movement at the elbow joint.
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(c) (i) Describe the function of neurone J.
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(ii) Explain why there are impulses in motor neurone G, but not in motor neurone H.
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(d) The action shown in Fig. 2.1 is an involuntary reflex action. The muscles can also be used for voluntary actions.
Explain how muscles are controlled during voluntary actions.
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The sweet potato plant, extit{Ipomoea batatas}, has fibrous roots and storage roots. Fibrous roots absorb water and ions from the soil. Storage roots store insoluble carbohydrates.
Fig. 3.1 shows the growth of these roots on a sweet potato plant.

Fig. 3.1
(a) Explain, using the term extit{water potential}, how fibrous roots absorb water.
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The membranes of root hair cells contain proteins for the absorption of ions.
(b) Describe how root hair cells are adapted for the absorption of ions.
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Sweet potato plants produce flowers to reproduce sexually. Sweet potato plants also reproduce asexually when shoots grow from the storage roots to form new plants.
Fig. 3.2 shows the life cycle of sweet potato. The diploid number of this species is 90.

Fig. 3.2
(c) Complete Fig. 3.2 by writing the number of chromosomes in the three boxes.
[2]
(d) State extbf{two} advantages and extbf{one} disadvantage of extit{asexual} reproduction for plants, such as sweet potato.
extit{advantage 1} .....................................................................................................................
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extit{advantage 2} .....................................................................................................................
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Proteins in the blood are involved in protection of the body.
Three proteins found in the blood are
• antibodies
• thrombin
• fibrinogen
(a) (i) Name the type of white blood cell that produces antibodies.
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(ii) Outline how antibodies protect the body.
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(b) Thrombin is an enzyme that catalyses the reaction:
fibrinogen → fibrin
(i) State when this reaction occurs.
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(ii) Explain how fibrin protects the body.
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An investigation was carried out to determine the effect of different temperatures on the activity of thrombin. The results are shown in Fig. 4.1.
[Image_1: Graph of thrombin activity]
(c) (i) Explain why thrombin functions slowly at 5°C and does not function at all at 70°C.
5°C
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70°C
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(ii) Suggest how the activity of thrombin was determined.
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(iii) State two conditions that would have been kept constant during the investigation.
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(a) State three characteristic features of birds that are visible in Fig. 5.1.
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(b)(i) Explain why wing length is an example of continuous variation.
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(b)(ii) Suggest a feature of reed warblers, other than wing length, that shows continuous variation.
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(c)(i) Describe the evidence from Table 5.1 that supports this conclusion.
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[Table_1]

(c)(ii) The researchers also suggested that more evidence was needed to make this conclusion. Suggest what other evidence would show that birds with wings 66-67 mm in length have the best chance of survival.
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(d) Scientists have discovered that genes are responsible for wing length in reed warblers. The most common length of wing has been 66-67 mm for many generations of these birds.
Explain how natural selection may be responsible for maintaining the mean wing length of reed warblers at 66-67 mm.
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(a) During stage 5 microorganisms break down organic matter consisting of cellulose, starch, protein and lipid (fat). The microorganisms multiply during this stage and are recycled.
Complete Fig. 6.2 by writing in the boxes the names of the enzymes used to catalyse the reactions shown. The first box has been completed for you.
[Image Fig. 6.2]
(b) State why it is important that sewage is treated.
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(c) At stage 5 in Fig. 6.1, oxygen and microorganisms are added.
Explain why oxygen is bubbled through the tank at this stage.
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(d) Suggest and explain the advantage of recycling microorganisms from stage 6 to stage 5 as shown in Fig. 6.1.
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(e) Explain why chlorine is added at stage 7.
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