Diffusion and Osmosis: Lab Quiz Answers
Study the set of five beakers shown here to answer questions 1 – 3:
1. Which beaker(s) contain(s) a solution that is hypertonic to the
bag?
1.
2.
3.
4.
5.
Beaker 3
Beakers 2 and 4
Beakers 1, 2, and 5
Beaker 4
Beakers 3 and 4
The correct answer is c. Hypertonic means that the solute
concentration in the beaker is higher than in the bag. This is true
for beakers 1, 2, and 5. Beaker 3 is isotonic to the bag, and beaker
4 is hypotonic to the bag.
2. Which bag would you predict to show the least change in mass
at the end of the experiment?
1.
2.
3.
4.
5.
The bag in Beaker 1
The bag in Beaker 2
The bag in Beaker 3
The bag in Beaker 4
The bag in Beaker 5
The correct answer is c. Since the two solutions shown are isotonic,
there will be no net gain or loss of water, and therefore a negligible
change in mass.
3. Arrange the beakers in order of the mass of the bags inside them
after the experiment has run for 30 minutes. List the bag that loses
the most mass first.
1.
2.
3.
4.
5.
1, 2, 3, 4, 5
1, 5, 2, 3, 4
4, 3, 2, 5, 1
3, 2, 1, 4, 5
2, 1, 5, 3, 4
The correct answer is e.
Refer to the figure below to answer questions 4 and 5.
4. In beaker B, what is the water potential of the distilled water in
the beaker, and of the beet core?
1. Water potential in the beaker = 0, water potential in the beet
core = 0
2. Water potential in the beaker = 0, water potential in the beet
core = -0.2
3. Water potential in the beaker = 0, water potential in the beet
core = 0.2
4. Water potential in the beaker cannot be calculated, water
potential in the beet core = 0.2
5. Water potential in the beaker cannot be calculated, water
potential in the beet core = -0.2
The correct answer is b. Since water potential = solute potential (0.4) + pressure potential (0.2), water potential = -0.2
5. Which of the following statements is true for the diagrams?
1. The beet core in beaker A is at equilibrium with the
surrounding water.
2. The beet core in beaker B will lose water to the surrounding
environment.
3. The beet core in beaker B would be more turgid than the
beet core in beaker A.
4. The beet core in beaker A is likely to gain so much water
that its cells will rupture.
5. The cells in beet core B are likely to undergo plasmolysis.
The correct answer is a. The water potential for both the distilled
water and the beet core in a is 0.