BIOLOGY PAPER 3 (2003-2009)

2003
Q1. To study the effect of camouflage on a predator-prey relationship
[Chapter 8]
Q2. To study the relationship between the concentration of CO₂ and the rate of photosynthesis [Chapter 6]

2004
Q1.To determine the % of vitamin C in fruit juices using DCPIP solution [Chapter 6]
Q2.To estimate the size of the bird population. [Chapter 8]

2005
Q1.To determine and compare the energy content in white bread and peanuts [Chapter 6]
Q2.To determine the concentration of the solution which will maintain the mass of plant tissues.[Chapter 3]

2006
Q1. To study the effect of concentration of albumen suspension on the rate of reaction of pepsin enzyme [Chapter 4]
Q2. To determine concentration of sucrose which is isotonic to cell sap of mango[Chapter 3]

2007
Q1.To study the effect of light intensity on the rate of photosynthesis of a Hydrilla sp. [Chapter 6]
Q2.To study the effect of temperature on the rate of anaerobic respiration in yeast [Chapter 7]

2008
Q1.To investigate the effect of light intensity on the population distribution of Pleurococcus sp. [Chapter 8]
Q2.To study the size of molecules that can diffuse through a semi permeable membrane [Chapter 3]

2009
Q1.To study the effect of light intensity on the rate of photosynthesis. [Chapter 6]
Q2.To study the effect of temperature on the rate of enzyme reaction. [Chapter 4]

2010
Q1. To investigate the effect of different duration of activity on the percentage of carbon dioxide in exhaled air.[Chapter 7]
Q2. To study the effect of interspecific competition between maize and paddy plants on their growth.[Chapter 8]

2007 Biology Paper 3-Question 2

Anaerobic respiration is the process of releasing energy from the breakdown of glucose in the absence of oxygen. Yeast can carry out anaerobic respiration in a glucose solution.

Glucose ---> Ethanol + Carbon dioxide + Energy

The rate of anaerobic respiration is affected by several factors such as temperature, pH values and nutrients.

Based on the above information and equation, design a laboratory experiment to investigate the effect of temperature on the rate of anaerobic respiration in yeast.

The planning of your experiment must include the following aspects:

§ Problem statement

§ Aim of investigation

§ Hypothesis

§ Variables

§ List of apparatus and materials

§ Technique used

§ Experimental procedure or method

§ Presentation of data

§ Conclusion

ANSWER

:1. Aim of investigation

To investigate the effect of temperature on the rate of anaerobic respiration in yeast.

2. Problem statement

What is the effect of temperature on the rate of anaerobic respiration (in yeast)?

3. Hypothesis

The higher the temperature, the higher the rate of anaerobic respiration (in yeast).

4. Variables

Manipulated variable: Temperature

Responding variable: Rate of anaerobic respiration//No of bubbles released//Time taken for lime water to turn chalky

Fixed variable: Volume/conc. of yeast suspension/glucose/pH/Time taken

5. Apparatus:

Boiling tube, Manometer/Capillary tube, Water bath//Beaker + thermometer,

Stopwatch, Marker/thread, Rubber stopper, Ruler, Rubber tubing, Retort stand, measuring cylinder

Material :

Yeast suspension / Yeast, Glucose solution, Paraffin oil (Yeast & Glucose – must have)

6. Technique

Using a ruler to record the change in height of the colored liquid/Record the number of bubbles released (after 10 minutes) using a stopwatch

//Calculating the rate of anaerobic respiration (in yeast) by using the formula :

Number of bubbles / Change in height

Time taken

//Take and record the time taken for the lime water to turn chalky using a stopwatch.

7. Procedure :

1. Set up the apparatus as shown in diagram.

2. Place the boiling tube with 15 cm³ of glucose solution in a beaker at 20^oC for 5 minutes.

3. Add 15 cm³ of yeast suspension into the boiling tube.

4. Mark the initial height of coloured liquid in manometer.

5. Start the stopwatch and mark the level of coloured liquid in the manometer after 10 minutes.

6. Record all data in a table.

7. Repeat step l, 3, 4, 5 and 6 by placing the boiling tubes in a water bath at temperatures of 30^oC, 40^oC and 50^oC.

8. Make sure all the joints of the apparatus are air tight //Repeat the experiment for each temperature to get average readings.

9. Plot a graph of rate of anaerobic respiration in yeast against temperature.

Precaution :

1. Ensure the temperature is stablised at the fixed temperature before taking the reading if the height of the coloured liquid//counting the number of bubbles released.

2. Make sure all the joints of the apparatus are air tight //Repeat the experiment for each temperature to get average readings.

8. Result: Draw a table

9. Conclusion:

Hypothesis is accepted. The higher the temperature, the higher the rate of anaerobic respiration in yeast.

2008 Biology Paper 3-Question 2

A semi permeable membrane in defined as a membrane that allows certain molecules to diffuse through it but does not allow the diffusion of other molecules. The diffusion of molecules through a semi permeable membrane depends on the size of the molecules.

Based on the above information, plan a laboratory experiment to study the size of molecules that can diffuse through a semi permeable membrane.

The planning of your experiment must include the following aspects:

§ Problem statement

§ Objective of investigation

§ Hypothesis

§ Variables

§ List of apparatus and materials

§ Technique used

§ Experimental procedure or method

§ Presentation of data

§ Conclusion

ANSWER

1. Aim:

To study the size of molecules that can diffuse through a semi permeable membrane.

2. Problem Statement:

What size molecules can diffuse through a semi permeable membrane/Visking tubing?

3. Hypothesis:

The smaller the molecules, the easier to pass through a semi-permeable membrane. //Water/glucose molecules can diffuse through the Visking tubing but not the starch/sucrose molecules

4. Variables:

Manipulated: Size of molecules /Type of substances

Responding: Diffusion of molecules through semi permeable membrane/ Visking tubing/ Change in water level in capillary tube (osmometer)

Fixed: Volume of solution in the Visking tubing/ Temperature/ Time

5. Apparatus:

Beaker, test tube, Bunsen burner, measuring cylinder, syringe, stopwatch.

Materials

Benedict's solution, iodine solution, Visking tubing, starch suspension, glucose solution, thread

6. Technique:

Carrying out food test on glucose/starch // Using Benedict’s solution/Iodine solution on the liquid outside the Visking tubing in the beaker and record the result// Measure and record the change in level of liquid in capillary tube using a ruler.

7. Procedure:

1. A Visking tubing is soaked in water to soften it.

2. The Visking tubing is tied at one end of the tube tightly with a piece of thread.

3. Visking tubing is filled with 10 ml glucose and 10 ml starch solution using a syringe.

4. The other end of the tube is tied tightly with a piece of thread.

5. The outer surface of the Visking tubing is rinsed with distilled water.

6. The Visking tubing is immersed into a beaker filled with distilled water.

7. After 20 minutes, a Benedict's test and iodine test carried out on the liquid outside the Visking tubing/ in the beaker.

8. The results of the both test are recorded in a table.

Precautions:

1. Rinse the outside surface of the Visking tubing.

2. Tie the Visking tubing tightly

8. Result: Draw a Table

9. Conclusion:

The smaller the molecules, the easier to pass through a semi-permeable membrane.Hypothesis is accepted.