IGCSE
Biology 0610
Paper 6 (Alternative to practical)
1
,Describe the tests for glucose and starch
Test for glucose (reducing sugars)
1. If the food is solid grind in a pestle and mortar and add a small quantity of water.
2. Add a depth of 1cm3 of the mixture/substance (to be tested) to a test tube.
3. Add a similar volume (1 cm depth) of Benedict’s reagent (original colour is blue).
4. Heat to at least 70oC for 2 minutes
5. If glucose (or another reducing sugar) is present the colour will change to
Yellow/orange/red (the closer to read the colour the higher the concentration of sugar)
Test for starch
1. If the food is solid grind in a pestle and mortar and add a small quantity of water.
2. Add a depth of 1cm3 of the mixture/substance (to be tested) to a test tube.
3. Add a similar volume (1 cm depth) of Iodine solution (original colour is orange/brown).
4. If starch is present the colour will change to blue/black (depending on the concentration of
the iodine solution)
N.b. 1. Iodine solution is not pure iodine, but actually potassium iodide.
2. Once iodine has changed colour to blue/black to indicate the present of starch this
colour change cannot be reversed. If amylase is added to digest the starch the iodine
remains a blue/black colour.
Describe experiments to investigate how enzyme activity can be affected by changes in
temperature.
The effect of temperature upon the amylase digestion of starch
Method:
• Select temperatures in range from 0°C to 100°C (controlled by water baths and ice-water
mixtures in troughs). Remember the optimum temperature will be between 30°C and 50°C.
• Place amylase solution and starch suspension separately in the water bath and wait until
they reach the desired temperature.
• Mix together amylase solution and the starch suspension. The mixture is then kept at the
same temperature.
• Immediately start the stop clock.
• To measure the rate of reaction, drops of the mixture can be collected at intervals of one
minute (starting at time zero) and added to individual iodine drops on a white tile.
• The time taken for the starch to disappear, i.e. the iodine remains orange/brown (remember
a blue/black colour indicates the presence of starch) is recorded.
• Repeat the procedure at each temperature.
Weaknesses:
• The rate of reaction can only be measured to an accuracy of one minute.
• Small concentrations of starch may persist making it difficult to decide when all the starch
has been digested.
2
, The effect of temperature upon the action of catalase
Method:
• Select temperatures in range from 0°C to 100°C (controlled by water baths and ice-water
mixtures in troughs). Remember the optimum temperature will be between 30°C and 50°C.
• Measure 10 cm3 hydrogen peroxide solution into a large test tube and place in a water bath
• Add 3 drops of detergent.
• Wait until the temperature is at the desired temperature.
• Prepare a cube of potato with each side measuring 1 cm in length.
• Add the cube to the boiling tube (try not to spill any hydrogen peroxide) and immediately
start the timer.
• Measure the height (h), of the foam every minute (from time zero) for 5 minutes.
• Repeat the procedure at each temperature.
N.b. Hydrogen peroxide is toxic and so great care needs to be taken with its use.
Weaknesses:
• The detergent may vary in its efficiency to capture the oxygen. Variance in the relative rates
of reaction can be measured, but not the actual volumes generated.
• Difficult to keep the cubes evenly shaped
Describe experiments to investigate diffusion and osmosis using living and non-living
systems.
Models of cells
Visking (dialysis) tubing
1. Tie the visking tubing at one end
2. Half fill with sucrose solution
3. Tie the other end
4. Measure the mass
5. Place in water for 30 mins
6. Dry the outside of the tubing and measure the mass again
7. The change in mass indicates the direction of osmosis and how quickly it has happened
Cubes of agar jelly
1. Cut three cubes out of the agar jelly. Each cube should measure 2cm x 2cm x 2cm
2. Place the agar cube in a beaker of potassium permanganate solution (purple dye)
3. After 10 mins remove one cube
4. Dry the surface
5. Cut the cube in half
6. Measure the distance (from the edge) that the potassium permanganate has reached by
diffusion.
7. After 20 mins and 30 mins remove the second and third cubes and similarly measure the
diffusion distance (repeat steps 4 – 6)
3
Biology 0610
Paper 6 (Alternative to practical)
1
,Describe the tests for glucose and starch
Test for glucose (reducing sugars)
1. If the food is solid grind in a pestle and mortar and add a small quantity of water.
2. Add a depth of 1cm3 of the mixture/substance (to be tested) to a test tube.
3. Add a similar volume (1 cm depth) of Benedict’s reagent (original colour is blue).
4. Heat to at least 70oC for 2 minutes
5. If glucose (or another reducing sugar) is present the colour will change to
Yellow/orange/red (the closer to read the colour the higher the concentration of sugar)
Test for starch
1. If the food is solid grind in a pestle and mortar and add a small quantity of water.
2. Add a depth of 1cm3 of the mixture/substance (to be tested) to a test tube.
3. Add a similar volume (1 cm depth) of Iodine solution (original colour is orange/brown).
4. If starch is present the colour will change to blue/black (depending on the concentration of
the iodine solution)
N.b. 1. Iodine solution is not pure iodine, but actually potassium iodide.
2. Once iodine has changed colour to blue/black to indicate the present of starch this
colour change cannot be reversed. If amylase is added to digest the starch the iodine
remains a blue/black colour.
Describe experiments to investigate how enzyme activity can be affected by changes in
temperature.
The effect of temperature upon the amylase digestion of starch
Method:
• Select temperatures in range from 0°C to 100°C (controlled by water baths and ice-water
mixtures in troughs). Remember the optimum temperature will be between 30°C and 50°C.
• Place amylase solution and starch suspension separately in the water bath and wait until
they reach the desired temperature.
• Mix together amylase solution and the starch suspension. The mixture is then kept at the
same temperature.
• Immediately start the stop clock.
• To measure the rate of reaction, drops of the mixture can be collected at intervals of one
minute (starting at time zero) and added to individual iodine drops on a white tile.
• The time taken for the starch to disappear, i.e. the iodine remains orange/brown (remember
a blue/black colour indicates the presence of starch) is recorded.
• Repeat the procedure at each temperature.
Weaknesses:
• The rate of reaction can only be measured to an accuracy of one minute.
• Small concentrations of starch may persist making it difficult to decide when all the starch
has been digested.
2
, The effect of temperature upon the action of catalase
Method:
• Select temperatures in range from 0°C to 100°C (controlled by water baths and ice-water
mixtures in troughs). Remember the optimum temperature will be between 30°C and 50°C.
• Measure 10 cm3 hydrogen peroxide solution into a large test tube and place in a water bath
• Add 3 drops of detergent.
• Wait until the temperature is at the desired temperature.
• Prepare a cube of potato with each side measuring 1 cm in length.
• Add the cube to the boiling tube (try not to spill any hydrogen peroxide) and immediately
start the timer.
• Measure the height (h), of the foam every minute (from time zero) for 5 minutes.
• Repeat the procedure at each temperature.
N.b. Hydrogen peroxide is toxic and so great care needs to be taken with its use.
Weaknesses:
• The detergent may vary in its efficiency to capture the oxygen. Variance in the relative rates
of reaction can be measured, but not the actual volumes generated.
• Difficult to keep the cubes evenly shaped
Describe experiments to investigate diffusion and osmosis using living and non-living
systems.
Models of cells
Visking (dialysis) tubing
1. Tie the visking tubing at one end
2. Half fill with sucrose solution
3. Tie the other end
4. Measure the mass
5. Place in water for 30 mins
6. Dry the outside of the tubing and measure the mass again
7. The change in mass indicates the direction of osmosis and how quickly it has happened
Cubes of agar jelly
1. Cut three cubes out of the agar jelly. Each cube should measure 2cm x 2cm x 2cm
2. Place the agar cube in a beaker of potassium permanganate solution (purple dye)
3. After 10 mins remove one cube
4. Dry the surface
5. Cut the cube in half
6. Measure the distance (from the edge) that the potassium permanganate has reached by
diffusion.
7. After 20 mins and 30 mins remove the second and third cubes and similarly measure the
diffusion distance (repeat steps 4 – 6)
3
