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Statement I : Haemophilia is a genetic disease that could be inherited and occurswithin a specific gender.

Statement II : Inheritance of haemophilia can be prevented in a family.

State your opinion and explain both the statements mentioned, based on Figure 8(b).l1.0 marksl

Paper 3 Time: t hour 30 minutes

Answer all questions.

1 A group of students carried out an experiment to determine the percentage of vitamin C infruit juices using DCPIP solution

The students carried out the following steps: l

Step 1: 1 ml DCPIP solution was placed in a test tube.Step 2: A few drops of ascorbic acid O.lVo was added to the DCPIP solution until there was

a colour change.

Figure 1(a) shows the method used in the experiment.

Beginning of experiment

End of experiment

Ascorbic acidsolution 0.1

m/ DCPIP solutionftlue)

DCPIP solution(colourless)

Figure 1(a)

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Steps 1 and 2 were repeated using lime and papaya juices instead of ascorbic acidsolution 0.17o.

The results to determine the percentage of vitamin C in the fruit juices are shown in Figurel(bxi), Figure l(bxii) and Figure l(bxiii).

Beginning of experiment

Ascorbic acidsolution 0.17o

Volume ofascorbic acidsolution 0.17o

Figure l(bxi)

Limejuice

Volume oflime juice

Figure l(bxii)

125

End of experiment

0ml

8

6

4

2

Beginning of experiment End of experiment

rdaian

(a) (i)

Papayajuice

Volume ofpapaya juice

Complete Table 1

the experimentFigure l(bxiii).

Figure Colour change in DCPIP solution

1ftXi)

l(bxii)

1(bXiii)

Table I

(ii) State the inference from the observations in (aXi).

[3 marhs]

Figure l(bxiii)

by stating the colour change in thebased on the results in Figure

DCPIP solution at the end ofl(b)(i), Figure l(bXii) and

ft)

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Fill in the boxes in Figure l(bxi), Figureof the following substances which cause(i) Ascorbic acid solution 0.1%(ii) Lime juice(iii) Papaya juice

13 marl?,sl

l(bxiii) to show the volumesin the DCPIP solution.

1(bxii) and Figurethe colour change

13 marksl

(c) (i) construct a table and record all data collected in the experiment.[3 marks]

(ii) Calculate the percentage of vitamin C in the following fruit juices:

Lime juice:

Papaya juice:

[3 marks]

(d) Describe the relationship between the volume of the fruit juice needed to bring about thecolour change in the DCPIP solution with the percentage of vitamin C in the fruit juice.

.Vo

Vo

(e) Complete Table 2 based on the experiment.

Variable Particulars to be implemented

1. Manipulatedvariable

How to alter the manipulated variable.

2. Respondingvariable

What to observe in the responding variable.

3. Controlledvariable

How to maintain the controlled variable.

Table 2

(0 State the hypothesis for the experiment.

13 marksl

13 marhsl

A student strongly shook the test tube while carrying out the experiment. Predict thevolume of ascorbic acid needed to produce a colour change in the DCPIP solution.

Explain your prediction.

[3 marks]

(g)

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(i)

(h) What can be deduced about vitamin C based on the results of the experiment?

[3 marhs]

Another group of students carried out the experiment to determine the percentage ofvitamin C but were provided with the following materials:

Pineapple juice

Classifiz the above list into materials to be tested and reagents based on their functionsin the experiment.

[3 marks]

A biologist did a study on a type of bird species in a fruit orchard.. It is found that these birdsfeed on insect pests. This is useful to the farmers because these birds can help control thepopulation of insect pests. With the assumption that these birds can be captured easily or canbe represented by small objects, design an experiment that can be carried out in the field orin a laboratory to estimate the size of the bird population.

Your field work or experimental planning need to include the following aspects:o Aim of investigatione Statement of hypothesis. Variableso List of apparatus and materials. Technique usedo Experimental procedure or methodo Collected datar Presentation of datar conclusion

t L7 marhsl

sb*-

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