Cambridge IGCSE Biology - 0610 - Supplement Paper 4 2013 Winter Zone 1

(a) Table 1.1 shows some features of the five groups of vertebrates.
Complete Table 1.1 to compare the five groups of vertebrates using a tick (✓) to indicate if the group shows the feature, or a cross (✗) if not.
The first row has been completed for you.

Table 1.1
[Table_1]

Fig. 1.1 shows a southern cassowary, Casuarius casuarius, which is a large bird that cannot fly. It lives in rainforests in northern Australia and southern New Guinea.
The cassowary feeds on fruits and helps to disperse seeds for many tree species, such as the cassowary plum.


(b) Suggest why the cassowary can digest the fruit but not the seeds of rainforest trees.
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(c) Describe one method of seed dispersal that does not require animals.
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(d) State two environmental conditions that seeds require so that they can germinate.
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(e) Cassowaries are an endangered species. Many are killed on the roads and development threatens their rainforest habitat.
Cassowaries, as with many other rainforest species, cannot survive in small nature reserves.
Suggest why species, such as cassowaries, cannot survive in small nature reserves.
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(a) (i) Explain the term balanced diet.
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(ii) State three factors that influence a person's nutritional needs.
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(b) Glucose is absorbed in the small intestine and transported in the blood. The kidneys filter the blood and reabsorb the glucose.
If the blood contains more than 180 mg of glucose per 100 cm³, the kidney cannot reabsorb it all and some is present in the urine. This figure is called the renal threshold.
A doctor suspects that a patient has diabetes because a urine test is positive for glucose.
The patient takes a glucose tolerance test by drinking a solution of glucose. The doctor records the patient's blood glucose concentration at 30 minute intervals for five and a half hours.
The results are plotted on Fig. 2.1.

[Image]
Fig. 2.1

(i) Draw a horizontal line on Fig. 2.1 to show the renal threshold. [1]
(ii) State the time period when the kidney will produce urine containing glucose.
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(iii) Sketch on Fig. 2.1 the blood glucose concentrations that the doctor might expect if he repeated this test on someone who does not have diabetes. [1]

(c) People who do not have diabetes maintain their blood glucose concentration below 180 mg per 100 cm³.
Explain how the body does this.
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(a) Starch, glucose and fructose are carbohydrates. Fructose syrup is used as a sweetening agent as an alternative to sucrose.

The flow chart in Fig. 3.1 shows how fructose is prepared from maize starch.



(i) Name enzyme 1.
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(ii) State why it is necessary to adjust the pH before an enzyme is added to the process.
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(b) Maize grains contain protease enzymes. With reference to the processes shown in Fig. 3.1, suggest why it is important that these enzymes do not contaminate the glucose syrup.
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(c) The formation of fructose syrup from glucose syrup is carried out at a temperature of 60 °C.
Suggest an important property of enzyme 2 that allows it to be used at temperatures as high as 60 °C.
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(d) Enzyme 2 is found naturally in many bacteria. Enzymes for use in washing powders are obtained from bacteria.
Describe how bacteria are used to produce enzymes for washing powders.
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(e) Pectinase is an enzyme that breaks down compounds known as pectins. Cell walls of fruits, such as apples and mangoes, contain pectins. Explain the advantages of using pectinase in fruit juice production.
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(a) Sickle cell anaemia is a genetic disorder that is found among people in certain parts of the world.
A sample of blood was taken from a person with sickle cell anaemia and examined with an electron microscope.
Fig. 4.1 shows some of the red blood cells in the sample.

Explain the problems that may occur as these cells circulate in the blood system.
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(b) The gene for haemoglobin exists in two alternative forms:
$H^A$ codes for the normal form of haemoglobin;
$H^S$ codes for the abnormal form of haemoglobin.
(i) State the name for the alternative forms of a gene.
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(ii) A child has sickle cell anaemia. The parents do not have this disorder.
Complete the genetic diagram to show how the child inherited the disorder.
Use the symbols $H^A$ and $H^S$ in your answer.
$\text{parental phenotypes} \hspace{0.5cm} \text{normal} \hspace{0.2cm} \times \hspace{0.2cm} \text{normal}$
$\text{parental genotypes} \hspace{0.5cm} H^A H^S \hspace{0.2cm} \times \hspace{0.2cm} H^A H^S$
$\text{gametes} \hspace{0.5cm} \bigcirc \hspace{0.2cm} \bigcirc \hspace{0.2cm} \bigcirc \hspace{0.2cm} \bigcirc$
$\text{child's genotype} \hspace{0.5cm} \text{................}$
$\text{child's phenotype} \hspace{0.5cm} \text{sickle cell anaemia}$ [2]
(iii) The parents are about to have another child.
What is the probability that this child will have sickle cell anaemia?
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(c) The maps in Fig. 4.2 show the distribution of sickle cell anaemia and malaria in some parts of the world.

(i) Explain why sickle cell anaemia is common in people who live in areas where malaria occurs.
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(ii) Suggest why sickle cell anaemia is very rare among people who live in Indonesia and northern Australia.
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(a) Complete Table 5.1 by naming \textbf{three} sense organs and the stimulus which each detects.

\textbf{Table 5.1}

\[ \begin{array}{|c|c|} \hline \textbf{sense organ} & \textbf{stimulus} \\ \hline & \\ \hline & \\ \hline & \\ \hline \end{array} \]

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(b) Reflexes are involuntary actions coordinated by reflex arcs like the one shown in Fig. 5.1.

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\textbf{Fig. 5.1}

(i) Explain what is meant by the term \textit{involuntary action}.

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(ii) The arm shown in Fig. 5.1 moves in response to the detection of heat.
Explain how the parts of the reflex arc shown in Fig. 5.1 bring about this response.

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(iii) Describe the advantages of simple reflexes, such as the one shown in Fig. 5.1.

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(c) The organs of the human body are coordinated by the nervous system.
Outline \textbf{one} other way in which these organs are coordinated.

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Savanna grasslands are an important ecosystem in Africa. Fig. 6.1 shows part of the nitrogen cycle in a grassland ecosystem in southern Africa.

(a) Name:
(i) a type of nitrogen-containing compound that is made by Cassia mimosoides, eaten by the impala and by the cheetah;
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(ii) the type of consumer as represented by the cheetah;
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(iii) the process by which urea is removed from the body of the animals as shown by D;
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(iv) process F.
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(b) Explain the importance of recycling nitrogen in ecosystems, such as the African savanna.
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(c) The most common plants that grow in the African savanna are grasses. There are very few legume plants, such as C. mimosoides.
Suggest reasons why C. mimosoides is a rare plant in the African savanna.
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(d) Explain why there are far fewer cheetah than impala.
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(e) The cheetah is an endangered species.
It is important to conserve their food supply and all the species that inhabit their ecosystem.
Explain why.
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