Centre Number Candidate Number Candidate Name

NAMIBIA SENIOR SECONDARY CERTIFICATE

BIOLOGY ORDINARY LEVEL 4322/3PAPER 3 Applied Practical Skills 2 hours

Marks 60 2013

Additional Materials: Ruler

INSTRUCTIONS AND INFORMATION TO CANDIDATES

• Candidates answer on the Question Paper in the spaces provided.• Write your Centre Number, Candidate Number and Name in the spaces at the top of this page.• Write in dark blue or black pen.• You may use a soft pencil for any diagrams, graphs or rough working.• Donotusecorrectionfluid.• You may use a non-programmable calculator.• Do not write in the margin For Examiner’s Use.

• Answer all questions.

• The number of marks is given in brackets [ ] at the end of each question or part question.

[Turn over© MoE/DNEA 4322/3/13

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This document consists of 11 printed pages and 1 blank page.

Republic of NamibiaMINISTRY OF EDUCATION

ORDINARY LEVEL

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1 (a) Fig. 1.1 shows the apparatus that can be used to show the loss of water from a plant.

top pan balance

water

layer of oil

Fig. 1.1

(i) Explainwhyoilisplacedontopofthewaterintheflask.

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(ii) Explain why the plant is added before the oil is carefully poured on top of the water.

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(iii) Explain how you would use this apparatus to measure the rate of transpiration, over seven days.

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(iv) Outline the results you would expect if the experiment was repeated when the temperature is 10°C warmer.

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(v) Using the same apparatus, describe how you could show that there are more stomata for water loss on the lower epidermis of the leaves than on the upper epidermis.

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2 Fig. 2.1 shows the apparatus that was set up in bright light and used to investigate photosynthesis in a leaf over a period of 12 hours.

hydrogencarbonateindicator

Fig. 2.1

The hydrogen carbonate indicator has the colour changes shown below.

purple red yellow

(air minus carbon dioxide) (normal air) (air plus carbon dioxide)

(a) State the colour of the indicator at

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(b) Describe how you would set up another tube to show that a leaf from the same plant respires.

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(c) (i) State the colour of the hydrogen carbonate indicator when the leaf has the same rate of respiration and rate of photosynthesis.

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(ii) Suggest what condition would you need to set up for the leaf to have the same rate of respiration and rate of photosythesis.

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3 (a) A learner described the test for reducing sugars to another learner as follows.

• Place a solid piece of food in a test-tube.

• Quarterfillthetest-tubewithBenedict’ssolution.

• Heat the test-tube gently for 10 minutes.

• A blue colour indicates the presence of a reducing sugar.

The list given by the learner is incorrect in a number of ways.

Describe the correct procedure for the reducing sugar test.

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(b) Eight solutions, labelled A to H were tested for the presence of starch, protein, fat and vitamin C.

The observations from these tests are given in Table 3.1.

Table 3.1

solution colour after performing food teststarch protein fat vitamin C

A brown purple clear colourlessB brown blue clear dark blueC brown blue cloudy dark blueD black blue cloudy dark blueE black blue clear dark blueF brown blue clear dark blueG black purple clear dark blueH brown blue clear colourless

(i) Which solution(s) were found to contain

1 starch but no fats? ........................................................................... [1]

2 protein but no vitamin C? ................................................................ [1]

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(ii) Which solutions were obtained from plant extract?

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(iii) Which solution(s) might you consider to be pure water?

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(iv) A learner suggested that solution D would provide the most energy.

Explain the reasons why this learner selected this solution.

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(v) Two other learners suggested that solution C or solution E would provide the most energy.

Using the information in Table 3.1, explain why it is not possible to know which of the three learners is correct?

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4 (a) Fig. 4.1 is a photograph of insect A.

X

Y

Fig. 4.1

Make a large labelled drawing of the head of insect A.

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(b) Fig. 4.2 is a photograph of insect B.

Fig. 4.2

(i) List three similarities which are visible in the photograph of the two insects.

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(ii) Construct a table, with ruled lines, and record four visible differences, between insect A and insect B.

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(c) The photograph in Fig. 4.1 shows insect A magnifiedX5.

Measure the distance between points X and Y on Fig. 4.1 and use this measurementtocalculatethemagnificationofyourdrawing,allowingfortheX5magnificationofthephotograph.

Distance between points X and Y: ................................................................

Magnificationofyourdrawing: ...................................................................... [4]

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5 The effect of pH on the activity of two protease enzymes, pepsin and trypsin, was investigated.

An enzyme solution, adjusted to the required pH, was placed in a hole made in the middle of a layer of gelatin in a petri dish. Gelatin is a jelly made of protein.

After one hour the activity of the enzymes was estimated by measuring the area of gelatin digested by the enzyme.

The results are shown in Fig. 5.1

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40

80

120

160

200

0

pH

area ofgelatindigested/mm2

PepsinTrypsin

Key

x

x

x

x

x

x

x

Fig. 5.1

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Fig. 5.2 shows the apparatus used at the start of the experiment and after an hour.

petri dishcontaining gelatin

hole in gelatin containing enzyme solution

0 hour

petri dishcontaining gelatin

hole in gelatin containing enzyme solution

1 hour

Fig. 5.2

(a) State the pH at which both enzymes had the same activity.

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(b) One of the results was due to an experimental error.

(i) Identify the

enzyme ............................................................................................ and

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(ii) Suggest three possible explanations for this experimental error.

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(c) The optimum pH for pepsin is pH 2. This condition is found in the stomach.

Explain how this condition is created in the stomach.

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