Understanding Solutions and Cell Environments
In this activity, we will examine how potato cores (cylindrical sections of potato) react when soaked in five different solutions for 24 hours.
What is a Solution?
A solution is made up of two parts:
Solvent: Usually water.
Solute: In this case, the solute is sucrose (sugar).
The concentration of the solution tells us how much solute is mixed with each volume of water. In this activity, we will express this concentration as a percentage.
Types of Solutions:
Hypertonic
Isotonic
Hypotonic
When we discuss how substances move in and out of cells, we need to understand three types of solutions:
Hypertonic Solution: Has a higher concentration of solutes compared to another solution.
Isotonic Solution: Has equal concentrations of solutes compared to another solution.
Hypotonic Solution: Has a lower concentration of solutes compared to another solution.
These solutions don’t exist independently; they must be compared to one another across a semi-permeable membrane (like a cell membrane).
Comparing Solutions:
To understand how these solutions affect cells, think about them in terms of comparison:
If the solution inside the cell (intracellular) is hypertonic: The solution outside the cell (extracellular) is hypotonic.
If the intracellular solution is hypotonic: The extracellular solution is hypertonic.
If both the intracellular and extracellular solutions are isotonic: They have equal concentrations.
Impact of Solutions on Intracellular Fluid
When a cell is placed in one of three types of solutions—hypertonic, isotonic, or hypotonic—the fluid inside and outside the cell will react in one of three ways:
1. Water Enters the Cell:
If the solution outside the cell is hypotonic (lower concentration of solutes), water moves into the cell.
This causes the cell to swell and its volume to increase.
You can measure this increase through a rise in the cell’s mass.
2. Water Leaves the Cell:
If the solution outside the cell is hypertonic (higher concentration of solutes), water moves out of the cell.
This causes the cell to shrink and its volume to decrease.
You can measure this decrease through a drop in the cell’s mass.
3. No Net Movement of Water:
If the solution is isotonic (equal concentrations of solutes), an equal amount of water enters and leaves the cell.
In this case, the volume and mass of the cell remain mostly unchanged.
Key Concept
Remember, water always moves toward the hypertonic solution, whether it’s inside or outside of a cell.
Wherever water goes, it carries mass with it, which affects the overall mass of the cell.
Instructions:
Calculate the percent change in mass for each potato core.
2. Use the information learned from the background reading and data analysis to answer the questions.
Four of the five solutions are a sucrose solution while one is distilled water, which lacks any solutes mixed in the solvent (water).
Calculate the percent change for each solution and indicate whether the mass increased, decreased, or did not change.
I recommend that you write down the data and your calculations on a sheet of paper to make it easier to refer to it as you answer each question, below. This will mitigate the necessity to scroll up and down, multiple times during the activity.
0% Sugar:
% Change -
Mass Change:
10% Sugar:
% Change -
Mass Change:
20% Sugar:
% Change -
Mass Change:
30% Sugar:
% Change -
Mass Change:
40% Sugar:
% Change -
Mass Change:
What does a positive percent-change indicate with respect to water and the potato core?
What does a negative percent-change indicate with respect to water and the potato core?
In which solutions did the cell gain water, lose water, or have no net gain/loss of water?
0% Sucrose
10% Sucrose
20% Sucrose
30% Sucrose
40% Sucrose
Gain water
Lost water
No net gain/loss of water
Review how water will behave when something is placed in a hypertonic solutions.
In which solution were the potato cores placed in a hypertonic solution?
Review how water will behave when something is placed in a hypertonic solutions.
In which solution were the potato cores placed in a hypotonic solution?
Review how water will behave when something is placed in a hypertonic solution.
In which solution were the potato cores placed in a isotonic solution?
How do you know if you place something in a hypertonic solution?
How do you know if you place something in a hypotonic solution?
How do you know if you place something in a hypertonic solution?
Understanding Solutions and Cell Environments
In this activity, we will examine how potato cores (cylindrical sections of potato) react when soaked in five different solutions for 24 hours.
What is a Solution?
A solution is made up of two parts:
Solvent: Usually water.
Solute: In this case, the solute is sucrose (sugar).
The concentration of the solution tells us how much solute is mixed with each volume of water. In this activity, we will express this concentration as a percentage.
Types of Solutions:
Hypertonic
Isotonic
Hypotonic
When we discuss how substances move in and out of cells, we need to understand three types of solutions:
Hypertonic Solution: Has a higher concentration of solutes compared to another solution.
Isotonic Solution: Has equal concentrations of solutes compared to another solution.
Hypotonic Solution: Has a lower concentration of solutes compared to another solution.
These solutions don’t exist independently; they must be compared to one another across a semi-permeable membrane (like a cell membrane).
Comparing Solutions:
To understand how these solutions affect cells, think about them in terms of comparison:
If the solution inside the cell (intracellular) is hypertonic: The solution outside the cell (extracellular) is hypotonic.
If the intracellular solution is hypotonic: The extracellular solution is hypertonic.
If both the intracellular and extracellular solutions are isotonic: They have equal concentrations.
Impact of Solutions on Intracellular Fluid
When a cell is placed in one of three types of solutions—hypertonic, isotonic, or hypotonic—the fluid inside and outside the cell will react in one of three ways:
1. Water Enters the Cell:
If the solution outside the cell is hypotonic (lower concentration of solutes), water moves into the cell.
This causes the cell to swell and its volume to increase.
You can measure this increase through a rise in the cell’s mass.
2. Water Leaves the Cell:
If the solution outside the cell is hypertonic (higher concentration of solutes), water moves out of the cell.
This causes the cell to shrink and its volume to decrease.
You can measure this decrease through a drop in the cell’s mass.
3. No Net Movement of Water:
If the solution is isotonic (equal concentrations of solutes), an equal amount of water enters and leaves the cell.
In this case, the volume and mass of the cell remain mostly unchanged.
Key Concept
Remember, water always moves toward the hypertonic solution, whether it’s inside or outside of a cell.
Wherever water goes, it carries mass with it, which affects the overall mass of the cell.
A solution consists of a solvent, which is usually
A
If the intracellular environment is hypotonic, then the extracellular solution must be
If an intracellular solution is hypotonic, then the extracellular solution could be:
Describe the movement of water when a cell is placed in a hypotonic solution. What effect will this have on a cell?
Describe the movement of water when a cell is placed in a hypertonic solution. What effect will this have on a cell?
Describe the movement of water when a cell is placed in an isotonic solution. What effect will this have on a cell?
