Answer Scheme Paper 3 Form 5

Mark Scheme Biology Paper 3 (4551/3)

MARKING SCHEMEMID-TERM EXAMINATION

BIOLOGY PAPER 3

1 (a) [KB0603 – Measuring Using Number]

Score Criteria 3 Able to record 4 readings of time taken in Table 1 correctly:

Sample answers Sample Time taken

M 15 sN 30 sO 55 sP 80 s

2 Able to record 3 correct and 1 incorrect answer .1 Able to record 2 correct and 2 incorrect answer. 0 Able to give one number, no response or wrong response

1 (b) (i) [KB0601 - Observation]

Score Criteria3 Able to state any two observations correctly according to 2 criteria:

Water sample ( Manipulated Variable) Time taken (Responding Variable)

Sample answers: 1. In sample M, the time taken for methylene blue solution to decolourised is 15 s2. In sample P, the time taken for methylene blue solution to decolourised is 80 s

2 Able to state any one observation correctly. orAble to state any two incomplete observations ( any 2 criteria)

Sample answers:1. In sample M/P, the time taken for methylene blue to decolourised is the shortest/longest.

1 Able to state any one idea of observation.(any 1criteria)Sample answers:

1. The time taken is different for the different water sample.

Or any other suitable answer.

0 Not able to response or wrong response.

1 (b) (ii) [KB0604 - Making inferences]

Score

Criteria

4551/3 [Lihat sebelah© Hak cipta Sekolah Berasrama Penuh, 2008


3 Able to make one logical inference for each observation based on the criteria

Level of water pollution. The time taken.

Sample answers: 1. In sample M, the time taken for methylene blue to decolourised is

shortest because the water sample is most polluted. 2. In sample P, the time taken for methylene blue to decolourised is

longest because the water sample is less polluted/ clean.

2 Able to make one logical inference for any one observation.or

Able to make one logical and incomplete inference base on one criterion for each observation.

Sample answer:

1. In sample M/P the level of pollution is higher/lower to show the water is clean/ dirty.

2. In sample M/P the time taken in shortest/highest because of clean/dirty.

1 Able to make an idea of inference with one criterion.Sample answers

1. Water pollution is higher/lower2. Different water sample has different time taken.

Or any suitable answer.


1(c) [KB061001 – Controlling Variables]

Variables How the variables are operatedManipulated:Samples of water

Use 4 samples water from different sources.

Responding:Time taken

Record the time taken for methylene blue to decolourised using stopwatch.

Fixed:Amount of methylene blue

Use the same amount of methylene blue for each sample.

1(d) KB0611- Making Hypothesis]

Score Criteria 3 Able to state a hypothesis to show a relationship between the manipulated variable

and responding variable and the hypothesis can be validated, based on 3 criteria:4551/3 [Lihat sebelah

2


Water sample (manipulated variable) Time taken (responding variable) Relationship

Sample answer : 1. The shorter the time taken, the water sample is most polluted, hence the B.O.D value is high. 2. The longer the time taken, the water sample is clean, hence the B.O.D value is low.

2 Able to state less accurate hypothesis to show a relationship between manipulated variable and responding variable base on 2 criteria.

Sample answer1. The shorter the time taken, the more polluted of water. 2. The higher/shorter B.O.D level, the water is more polluted/clean.

1 Able to state idea of hypothesis to show a relationship between manipulated variable and responding variable base on 1 criterion.

Sample answer1. Level of water pollution is varied.


1(e) (i) [KB0606 – Communicating]

Score Criteria 3 Able to draw and fill a table with all columns and rows labeled with complete unit

Sample answers

Water sample Time taken for colour changes of water sample (s)M 15N 30O 55P 80

2 Able to draw a table with incomplete data 1 Able to draw a table without data 0 Not able to response or wrong response.

1(e) (ii) [KB0608 – Interpreting Data]

Score Criteria 3 Able to state clearly and accurately the relationship between the time taken and the

amount of dissolved oxygen based on the criteria: P1- the time taken. P2- B.O.D value

Sample answer:

4551/3 [Lihat sebelah

3


1. Rapid decolourisation of methylene blue solution show the lower concentration of dissolved oxygen , hence the B.O.D value is high.

2 Able to state clearly but less accurate the relationship.1 Able to state the idea of the relationship . 0 Not able to response or wrong response.

(f) [KB0605] [predicting ]

Score Criteria 3 Able to predict the result accurately base on 2 criteria.

The time taken. The amount of oxygen.

Sample answer: 1. The time taken for methylene blue to decolourised is more than 55 s

because the amount of dissolved oxygen is high. Methylene blue is used to analyse the presence of oxygen in water. The more dissolved oxygen in water the colour of methylne blue is decolourised slowly.

2 Able to predict result less accurate. 1. The time taken for methylene blue to decolourised is more than 55 s.

1 Able to give idea of the result.1. The time taken is longer.


(g) [KB0609 – define operationally]

Score

Criteria

3 Able to define operationally base on 3 criteria Amount of oxygen. Decolourisation of methylene blue. Time taken

Sample answer: 1. B.O.D means the more/longer time taken for the methylene blue

decolorized, the water sample is less polluted/clean because the amount of oxygen is high.

2 Able to predict the result less accurate base on 1 criteriaSample answer:

1. A high B.O.D value means the time taken for the methylene blue to decolourised is rapid/shortest.

1 Able to give idea of the result

1. The shortest the time taken, the more polluted the water.


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(h) [KB0602 – Classifying]

Score

Criteria

3 Able to state the relationship based on the 2 criteria Level of pollution Time taken

Sample answer:

1. Slow decolourisation of the methylene blue shows that the B.O.D value is low and the water is less polluted.

2 Able to state relationship less accurate base on 1 criteriaSample answer:

1. . Slow decolourisation of the methylene blue show the water is clean.

1 Able to give idea of the result 1. Different sample of water affect the time taken


Score Criteria 3 Able to classify all 3 pairs of the time taken and level of pollution.

Sample answer

Sample Time taken Level of pollutionStation A 2 hour PollutedStation B 1 hour Very Polluted Station C 4 hour Clean

2 Able to classify 2 pairs

1 Able to classify 1 pairs



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Aspect Criteria Score

Problem statement

Able to state the problem statement correctly : C1 : Manipulated Variable C2 : Responding variable R : Question form and have relationship

Sample Answer : 1. What is the effect of starch / substrate concentration on the rate of

amylase reaction / activity ? 2. How starch / substrate concentration affects the rate of amylase

reaction / activity ?

# Without question mark (?) – score 2

3

Able to give a statement of identified problem but incomplete.

Sample Answer: 1. What is the effect of starch / substrate concentration on amylase? 2. How does starch affect the rate of reaction / activity of amylase?

2

Able to give idea of a statement of identified problem.

Sample Answer: 1. What is the starch / substrate concentration? 2. Starch / substrate concentration affects amylase.

1

No response or wrong response 0

Aspect Criteria ScoreHypothesis Able to state the hypothesis correctly by relating two variables.

Criteria set: C1 : State the manipulated variable C2 : State the responding variable R: Show the specific relationship and direction between the manipulated variable and the responding variable. Answer must have C1, C2 and R

Sample Answer : 1. The rate of amylase / enzyme reaction /activity increases with the

increase in starch / substrate concentration (until it reaches a maximum rate).

2. As the concentration of amylase / enzyme increases, the time taken for the hydrolysis of starch to be completed increases.

3

Able to make a statement of hypothesis which relates the manipulated variable to the responding variable. Answer must have C1 and C2 but without correct relationship

Sample Answer : 1. Starch / Substrate concentration increases the rate of amylase /

enzyme reaction / activity. 2. Starch / Substrate concentration affects the rate of amylase /

enzyme reaction / activity.

2


6


Able to state an idea of a statement of hypothesis. Sample Answer: 1. The rate of amylase / enzyme reaction / activity increases.

1

No response or wrong response. 0


Variables

All three variables must be correct : Manipulated variable : Concentration of starch suspension Responding Variable : Time taken for the hydrolysis of starch to be

completed / the mixture stops turning blue black in colour when tested with iodine solution // rate of salivary amylase / enzyme reaction / activity

Constant Variable : Amylase / Enzyme concentration // temperature

3

Any two variables correct 2Any one variable correct 1


Materials and

apparatus

Able to state all the materials and apparatus

Note: Must have test tubes, thermometer, salivary amylase, iodine and starch suspension to get a tick.

Sample answer: Apparatus: test tubes, stopwatch, syringes, glass rods, white tile with

groove, droppers, thermometerMaterials: salivary amylase, iodine solution, starch suspensions at

different concentrations (0.1%, 0.2%, 0.3%, 0.4%, 0.5%, 0.6%), distilled water

7A +4M

3


groove, droppersMaterials: salivary amylase, iodine solution, starch suspensions at

different concentrations (0.1%, 0.2%, 0.3%, 0.4%, 0.5%, 0.6%)

6A +3M

2


grooveMaterials: salivary amylase, iodine solution, starch suspensions at

different concentrations 5A

+3M

1


Aspect Criteria Score Procedure Able to state all the steps in carrying out the experiment successfully.


7


K1: Steps to set up the apparatus (any 4)K2: Steps to handle fixed variables (any 1)K3: Steps to handle manipulated variablesK4: Steps to handle responding variablesK5: Precautionary steps/steps taken for accurate results/ readings

(any1)Scoring rubricAll K1-K5 present

3

Any 3-4K present 2

Any 1-2K present 1


Sample answer: Procedure Notes

K1 1. Six test tubes are labelled A to F.K2+K5

2. 5ml of starch suspensions of different concentration are poured into the following test tubes using different syringes. A: 0.1% of starch suspensionB: 0.2% of starch suspensionC: 0.3% of starch suspensionD: 0.4% of starch suspensionE: 0.5% of starch suspensionF: 0.6% of starch suspension

K2 3. The test tubes are immersed in water bath at 37ºC.K1 4. Drops of iodine solution are added separately onto the grooves of a

white tile using a syringes.K2 5. 1ml of 0.1% amylase is added to test tube A.K1 6. Stopwatch is activated immediately. (0 minutes)K1 7. The contents are stirred with a glass rod. K1 8. A drop of mixture is tested with iodine solution on the white tile.K5 9. At every sampling the dropper must be rinsed with clean distilled

water. K5 10. The steps are repeated at 30 second intervals until the mixture stops

turning blue black in colour when tested with iodine solution.K4 11. Time taken for the hydrolysis of starch to be completed is recorded in

the table. K1+K4

12. Steps 4-11 are repeated with test tubes B,C,D,E and F.

K1 13. A graph of the rate of amylase activity against starch concentration is plotted.

5K = 3m

3-4K = 2m

1-2K= 1m


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Presentation of data

Able to draw a complete table to record the relevant data base on the three criteria:

-Column for manipulated variable with correct unit: concentration of starch suspension (%)

-Column for responding variable with correct unit: Time taken for the hydrolysis of starch to be completed (minute)

-Rate of enzyme reaction =

1Time (minute-1) // graph

Test tubeConcentration

of starch suspension (%)

Time taken for the hydrolysis of starch to be

completed (minute)

Rate of enzyme

reaction =1Time

(minute-1)A 0.1B 0.2C 0.3D 0.4E 0.5F 0.6

2

Able to state any ONE criteria 1No response or wrong response. 0

Total mark = 17 marks


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Answer Scheme Paper 3 Form 5

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