Cell Structure and Function � Tonicity and pH
This document explains concepts related to cell biology.
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to fill out and hand in to your instructor
Name:___________________________Date:________________________
Cell Structure and Function – Tonicity and pH
Exercise 1: The Case of the Limp Vegetable
Results:
Table 1: Comparison of States of Tonicity
Test
Tube
Solute/Solvent Appearance of
Potato Strip
Type of Tonicity Gradient: Is the potato
strip in a Hypertonic, Hypotonic or
Isotonic
at the beginning of this exercise?
1 Sugar solution Crispy Hypotonic solution
2 Salt solution Limp Hyper tonic solution
Conclusions:
A. How does each potato strip look? Which one is limp and which one is crisp?
Answer The potato strip in first test tube appears crispy, while in other appears limp.
That is the potato strip present in sugar solution is crispy, while in salt solution is limp.
B. How can the difference be explained?
Answer The difference is due to concentration of solution,
C. What caused the change in appearance of each strip?
Answer If solution is less concentrated (sugar solution) than potato, its water enters in it and
provides potato’s strip a crisp appearance, but if it is more concentrated than potato, then,
water from potato comes outside and potato’s strip limps.
to fill out and hand in to your instructor
Name:___________________________Date:________________________
Cell Structure and Function – Tonicity and pH
Exercise 1: The Case of the Limp Vegetable
Results:
Table 1: Comparison of States of Tonicity
Test
Tube
Solute/Solvent Appearance of
Potato Strip
Type of Tonicity Gradient: Is the potato
strip in a Hypertonic, Hypotonic or
Isotonic
at the beginning of this exercise?
1 Sugar solution Crispy Hypotonic solution
2 Salt solution Limp Hyper tonic solution
Conclusions:
A. How does each potato strip look? Which one is limp and which one is crisp?
Answer The potato strip in first test tube appears crispy, while in other appears limp.
That is the potato strip present in sugar solution is crispy, while in salt solution is limp.
B. How can the difference be explained?
Answer The difference is due to concentration of solution,
C. What caused the change in appearance of each strip?
Answer If solution is less concentrated (sugar solution) than potato, its water enters in it and
provides potato’s strip a crisp appearance, but if it is more concentrated than potato, then,
water from potato comes outside and potato’s strip limps.
Discussion:
A. Did the experiment support or refute the initial hypothesis? Explain why.
Answer Yes, as initially, our hypothesis was that, salt solution may provide limp appearance to
potato, hence, it has been proven true,
B. Explain why vegetables stored in a refrigerator over time become limp.
Answer As, with the passage of time, dehydration occurs so, due to removal of water, they
appear limp.
C. In this exercise two of the three types of tonicity gradients were observed. Suggest an
experiment to provide an example of the third type of tonicity gradient in action.
Answer In third kind of experience, we may take a solution, that is isotonic with water and will
not show any effect on its appearance as no, net movement of water will take place.
D. What kinds of cell environmental conditions might affect tonicity in cells?
Answer Temperature may enhance the rate of above reactions hence , appearance of cell may
change quite earlier.
Exercise 2: Turgor
Results:
Table 2: Comparison of Turgor Pressure States in Elodea Leaf Cells
Solute/Solvent
Scientific Term for Condition:
Is the leaf in a Hypertonic, Hypotonic or
Isotonic at the beginning of this
exercise?
Appearance of
Cells at End of
Procuedure
Water Isotonic No change
10% Sodium Chloride,
NaCl solution
Hyper tonic Shrinkage
Conclusion:
A. How can the differences in appearance of the cells in the two solutions be explained?
Answer Due to water no impact on leaf’s turgor pressure occurs as there is no difference in
Concentration of both and it remains turgid as it was in beginning.
A. Did the experiment support or refute the initial hypothesis? Explain why.
Answer Yes, as initially, our hypothesis was that, salt solution may provide limp appearance to
potato, hence, it has been proven true,
B. Explain why vegetables stored in a refrigerator over time become limp.
Answer As, with the passage of time, dehydration occurs so, due to removal of water, they
appear limp.
C. In this exercise two of the three types of tonicity gradients were observed. Suggest an
experiment to provide an example of the third type of tonicity gradient in action.
Answer In third kind of experience, we may take a solution, that is isotonic with water and will
not show any effect on its appearance as no, net movement of water will take place.
D. What kinds of cell environmental conditions might affect tonicity in cells?
Answer Temperature may enhance the rate of above reactions hence , appearance of cell may
change quite earlier.
Exercise 2: Turgor
Results:
Table 2: Comparison of Turgor Pressure States in Elodea Leaf Cells
Solute/Solvent
Scientific Term for Condition:
Is the leaf in a Hypertonic, Hypotonic or
Isotonic at the beginning of this
exercise?
Appearance of
Cells at End of
Procuedure
Water Isotonic No change
10% Sodium Chloride,
NaCl solution
Hyper tonic Shrinkage
Conclusion:
A. How can the differences in appearance of the cells in the two solutions be explained?
Answer Due to water no impact on leaf’s turgor pressure occurs as there is no difference in
Concentration of both and it remains turgid as it was in beginning.
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