Experiment 3.1:
Aim: To study the absorption of glucose through a Visking tube.
Problem statement: Can glucose diffuse through a Visking tube?
Hypothesis: Glucose can diffuse through a Visking tube.
Variables:
(a) Constant variables: Type and size of Visking tube, temperature, time
(b) Manipulated variable: Content in the Visking tube
(c) Responding variable: Presence of glucose in the distilled water
Materials: 1% starch suspension, glucose solution, Visking tube, iodine solution, Benedict’s solution and distilled water
Apparatus: Boiling tubes, beaker, test tubes, Bunsen burner, stopwatch, tripod stand, wire gauze and thread
Procedure:
1. Soak two Visking tubes in water to soften them.
2. Tie up one end of both Visking tubes using thread.
3. Pour 10 ml of starch suspension into one Visking tube and 10 ml of glucose solution into the other Visking tube.
4. Tie up the other end of both Visking tubes using thread.
5. Rinse both Visking tubes using distilled water until clean.
6. Set up the apparatus as shown in Figure 3.17.
7. Carry out Benedict’s test and iodine test on the distilled water in boiling tubes P and Q.
8. Record your observations in the following table.
9. Leave the apparatus for 30 minutes. Then, repeat step 7.
10. Record your observations in the following table.
Observation:
Questions
1. What is represented by the Visking tube and distilled water in the beaker?
2. State two precautionary steps that need to be taken when carrying out this experiment.
3. What inference can be made based on the observations of
(a) boiling tube P?
(b) boiling tube Q?
4. What conclusion can be made from this experiment?
Aim: To study the absorption of glucose through a Visking tube.
Problem statement: Can glucose diffuse through a Visking tube?
Hypothesis: Glucose can diffuse through a Visking tube.
Variables:
(a) Constant variables: Type and size of Visking tube, temperature, time
(b) Manipulated variable: Content in the Visking tube
(c) Responding variable: Presence of glucose in the distilled water
Materials: 1% starch suspension, glucose solution, Visking tube, iodine solution, Benedict’s solution and distilled water
Apparatus: Boiling tubes, beaker, test tubes, Bunsen burner, stopwatch, tripod stand, wire gauze and thread
Procedure:
1. Soak two Visking tubes in water to soften them.
2. Tie up one end of both Visking tubes using thread.
3. Pour 10 ml of starch suspension into one Visking tube and 10 ml of glucose solution into the other Visking tube.
4. Tie up the other end of both Visking tubes using thread.
5. Rinse both Visking tubes using distilled water until clean.
6. Set up the apparatus as shown in Figure 3.17.
7. Carry out Benedict’s test and iodine test on the distilled water in boiling tubes P and Q.
8. Record your observations in the following table.
9. Leave the apparatus for 30 minutes. Then, repeat step 7.
10. Record your observations in the following table.
Observation:
Questions
1. What is represented by the Visking tube and distilled water in the beaker?
2. State two precautionary steps that need to be taken when carrying out this experiment.
3. What inference can be made based on the observations of
(a) boiling tube P?
(b) boiling tube Q?
4. What conclusion can be made from this experiment?
Answer:
1. Small intestine, blood
2. (a) Tie the Visking tubes securely
(b) Wash the Visking tubes thoroughly before putting them into the distilled water.
3. (a) Iodine solution remains brown because the size of starch molecules is big and cannot diffuse through the Visking tube.
(b) Benedict’s solution forms brick red precipitate because the size of glucose is small and can diffuse through the Visking tube.
4. Starch consists of big molecules that cannot diffuse through the Visking tube. Glucose consists of small molecules that can diffuse through the Visking tube.
1. Small intestine, blood
2. (a) Tie the Visking tubes securely
(b) Wash the Visking tubes thoroughly before putting them into the distilled water.
3. (a) Iodine solution remains brown because the size of starch molecules is big and cannot diffuse through the Visking tube.
(b) Benedict’s solution forms brick red precipitate because the size of glucose is small and can diffuse through the Visking tube.
4. Starch consists of big molecules that cannot diffuse through the Visking tube. Glucose consists of small molecules that can diffuse through the Visking tube.