chapter 3 written practical 2

8/7/2019 Chapter 3 Written Practical 2

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Chapter 3 Written Practical 21 An experiment is carried out to study the effect of different concentration of sucrose on the

size of potato discs with the following steps:Step 1: Using a cork borer, 5 cylinders of potato tissue were obtained. Each cylinder was thensliced to make 10 discs of uniform size.Step 2: 10 disc were taken and measured as shown in Diagram 1.1.

Diagram 1.1

Step 3: The discs were immersed in 100 ml of distilled water in a Petri dish labelled J.Step 4: Steps 2 and 3 were repeated for the remaining discs which were then placed in Petri

dishes labelled K, L, M, and N, each containing sucrose solutions as shown in Table1.1.

Petri dish SolutionJ Distilled water K 0.2M sucrose solutionL 0.4M sucrose solutionM 0.6M sucrose solution N 0.8M sucrose solution

Table 1.1

Step 5: After immersion period for 30 minutes, the disc in each Petri dish were measured. Theresults of the experiment are shown in Table 1.2.

Petri dish Length of 10 potato disc after immersion for 30 minutes/ cm

J

K

L

M

N

(a) Record the final length of the 10 disc for each of the solutions in the spaces provided inTable 1.2. [3 marks ]

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(b) (i) Based on Table 1.2, state two observations that can be obtained from this experiment.1.

2.

[3 marks ](ii) State the inference from the observations in (b)(i).

1.

2.

[3 marks ](c) Complete Table 1.3 based on the experiment.

Variable Method to handle the variable

1. Manipulated variable

2. Responding variable

3. Controlled variable

Table 1.3 [3 marks ](d) State the hypothesis for the experiment.

[3 marks ]

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(e) (i) Construct a table to record the data collected from this experiment. Your table shouldcontain the following titles. Concentration of sucrose solution Initial length of 10 discs Final length of 10 discs Change in length [3 marks ]

(ii) Draw the graph of change in the length of the 10 potato discs against the concentrationof sucrose solution. [3 marks ]

(f) Based on the graph, explain the relationship between concentration of the sucrose solutionand the change in length of the potato discs.

[3 marks ](g) The experiment is repeated but this time each potato cylinder is sliced into 10 thicker discs.

The initial length of 10 discs is 11.0 cm. Predict and explains the change in diameter of the potato discs if they are immersed in distilled water.

[3 marks ](h) Based on the results of the experiment, what can you deduce about osmosis?

[3 marks ](i) Classify the following as material or apparatus as used in this experiment. [3 marks ]

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Distilled water, sucrosesolution, Petri dishes,measuring cylinder, ruler,

potato

chapter 3 written practical 2

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