Diffusion and Osmosis
Background Reading Notes.
1. The water you consume enters your cells through diffusion.
2. Diffusion: the basic principle where molecules move from a high concentration area to a
low concentration area.
3. Cell membranes restrict the movement of some molecules but allow water molecules to enter
and leave the cell.
4. When cells are placed in pure water, water moves into the cell trying to equalize
the concentration of molecules inside and outside the cell.
- In pure water, this is impossible for animal cells, and water enters the cell until it bursts.
- However, plant cells are protected from rupturing by a cell wall.
- You (a human) would have to drink a LOT of water and very quickly to experience
cellular problems from overhydration!
5. Cell membranes: barriers that separate the inner contents of the cell from its environment.
- Cells allow different types of materials to cross the cell membrane.
- Example: Nutrients must enter the cell, whereas waste products must exit.
6. The cell membrane is semipermeable.
- Semipermeable membranes allow certain molecules and ions to enter and exit freely
via diffusion.
- This relatively slow process relies on the random motion of the molecules to ultimately
balance out the concentration differential on either side of the membrane so that
the concentration inside the cell and the concentration outside the cell are
appropriately matched.
- The cell is also capable of actively transporting molecules and ions across its membrane, as
well as regulating the net transport of particles that ordinarily move via passive diffusion.
7. A similar phenomenon is that of osmosis.
- Water is a very small molecule, and it readily diffuses across the cell membrane.
- When particles are unable to cross the membrane to equalize their concentration on
either side, the water in which they are dissolved can cross the cell membrane instead.
- This equalizes the concentrations of the dissolved particles within and outside the cell.
- The net force driving this transport of water is called the osmotic pressure.
8. Tonicity: the relative concentrations used to determine the direction of osmosis.
- An isotonic solution has the same concentration as the interior of the cell.
- A hypertonic solution has a higher concentration than the interior of the cell.
- A hypotonic solution has a lower concentration than the interior of the cell.
9. When a plant cell is placed in a hypertonic solution, water leaves the cell.
- The cell shrinks and becomes plasmolyzed.
- Plasmolysis: when the cell membrane pulls away from the cell wall.
- The cell membrane will separate from the cell wall and move towards the center of the cell.
- The cytoplasm and the organelles suspended within it, such as chloroplasts, will
move towards the center of the cell.
10. When a plant cell is placed in a hypotonic solution, water enters the cell.
- The cell swells and becomes turgid.
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, -The cell membrane will be pushed against the cell wall because of the large amount of
water entering the cell.
- The cytoplasm and the chloroplasts will also be pushed towards the cell wall.
11. When a plant cell is placed in an isotonic solution, there is no net movement of water.
- The concentration of the solutions inside and outside the cell are equal.
- The cell membrane and the cell wall will rest next to each other.
- The cytoplasm and chloroplasts will be evenly distributed throughout the cell.
About This Lab Notes.
1. When starch and iodine interact, the solution changes color and becomes black.
2. If the solution is not black, then either starch or iodine have been prevented from crossing
the membrane of the diffusion bag.
Lab Notes.
Experiment 1: Membrane Size Selectivity
1. Before putting the diffusion bag (of water and Iodine) into the beaker (of water and starch),
the water in the beaker was clear and the liquid in the diffusion bag was a golden looking
color.
2. Afterwards, the liquid in the beaker turned into a dark grey/black looking color. The liquid in
the diffusion bag remained the same golden looking color.
Experiment 2: Relative Concentration and Osmosis
1. Diffusion Bag 1: (100mL Sucrose Solution / 100mL Total) X 20% = 20% Sucrose
2. Diffusion Bag 2: (75mL Sucrose Solution / 100mL Total) X 20% = 15% Sucrose
3. Diffusion Bag 3: (50mL Sucrose Solution / 100mL Total) X 20% = 10% Sucrose
4. Diffusion Bag 4: (25mL Sucrose Solution / 100mL Total) X 20% = 5% Sucrose
5. Four Beakers: (100mL Sucrose Solution / 200mL Total) x 20% = 10% Sucrose
6. Beaker 1 will be hypotonic because Diffusion Bag 1 has a less amount of sucrose concentration.
7. Beaker 2 will be hypotonic because Diffusion Bag 2 has a less amount of sucrose concentration.
8. Beaker 3 will be isotonic because Diffusion Bag 3 has the same amount of
sucrose concentration.
9. Beaker 4 will be hypertonic because Diffusion Bag 4 has less sucrose concentration.
My predictions are that:
10. Diffusion Bag and Beaker 1: Once diffusion has taken place, the mass will increase in the
bag and decrease in the beaker.
11. Diffusion Bag and Beaker 2: Once diffusion has taken place, the mass will increase in the bag
and decrease in the beaker.
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Background Reading Notes.
1. The water you consume enters your cells through diffusion.
2. Diffusion: the basic principle where molecules move from a high concentration area to a
low concentration area.
3. Cell membranes restrict the movement of some molecules but allow water molecules to enter
and leave the cell.
4. When cells are placed in pure water, water moves into the cell trying to equalize
the concentration of molecules inside and outside the cell.
- In pure water, this is impossible for animal cells, and water enters the cell until it bursts.
- However, plant cells are protected from rupturing by a cell wall.
- You (a human) would have to drink a LOT of water and very quickly to experience
cellular problems from overhydration!
5. Cell membranes: barriers that separate the inner contents of the cell from its environment.
- Cells allow different types of materials to cross the cell membrane.
- Example: Nutrients must enter the cell, whereas waste products must exit.
6. The cell membrane is semipermeable.
- Semipermeable membranes allow certain molecules and ions to enter and exit freely
via diffusion.
- This relatively slow process relies on the random motion of the molecules to ultimately
balance out the concentration differential on either side of the membrane so that
the concentration inside the cell and the concentration outside the cell are
appropriately matched.
- The cell is also capable of actively transporting molecules and ions across its membrane, as
well as regulating the net transport of particles that ordinarily move via passive diffusion.
7. A similar phenomenon is that of osmosis.
- Water is a very small molecule, and it readily diffuses across the cell membrane.
- When particles are unable to cross the membrane to equalize their concentration on
either side, the water in which they are dissolved can cross the cell membrane instead.
- This equalizes the concentrations of the dissolved particles within and outside the cell.
- The net force driving this transport of water is called the osmotic pressure.
8. Tonicity: the relative concentrations used to determine the direction of osmosis.
- An isotonic solution has the same concentration as the interior of the cell.
- A hypertonic solution has a higher concentration than the interior of the cell.
- A hypotonic solution has a lower concentration than the interior of the cell.
9. When a plant cell is placed in a hypertonic solution, water leaves the cell.
- The cell shrinks and becomes plasmolyzed.
- Plasmolysis: when the cell membrane pulls away from the cell wall.
- The cell membrane will separate from the cell wall and move towards the center of the cell.
- The cytoplasm and the organelles suspended within it, such as chloroplasts, will
move towards the center of the cell.
10. When a plant cell is placed in a hypotonic solution, water enters the cell.
- The cell swells and becomes turgid.
This study source was downloaded by 100000832558064 from CourseHero.com on 04-28-2022 01:41:30 GMT -05:00
https://www.coursehero.com/file/35972247/Diffusion-and-Osmosisdocx/
, -The cell membrane will be pushed against the cell wall because of the large amount of
water entering the cell.
- The cytoplasm and the chloroplasts will also be pushed towards the cell wall.
11. When a plant cell is placed in an isotonic solution, there is no net movement of water.
- The concentration of the solutions inside and outside the cell are equal.
- The cell membrane and the cell wall will rest next to each other.
- The cytoplasm and chloroplasts will be evenly distributed throughout the cell.
About This Lab Notes.
1. When starch and iodine interact, the solution changes color and becomes black.
2. If the solution is not black, then either starch or iodine have been prevented from crossing
the membrane of the diffusion bag.
Lab Notes.
Experiment 1: Membrane Size Selectivity
1. Before putting the diffusion bag (of water and Iodine) into the beaker (of water and starch),
the water in the beaker was clear and the liquid in the diffusion bag was a golden looking
color.
2. Afterwards, the liquid in the beaker turned into a dark grey/black looking color. The liquid in
the diffusion bag remained the same golden looking color.
Experiment 2: Relative Concentration and Osmosis
1. Diffusion Bag 1: (100mL Sucrose Solution / 100mL Total) X 20% = 20% Sucrose
2. Diffusion Bag 2: (75mL Sucrose Solution / 100mL Total) X 20% = 15% Sucrose
3. Diffusion Bag 3: (50mL Sucrose Solution / 100mL Total) X 20% = 10% Sucrose
4. Diffusion Bag 4: (25mL Sucrose Solution / 100mL Total) X 20% = 5% Sucrose
5. Four Beakers: (100mL Sucrose Solution / 200mL Total) x 20% = 10% Sucrose
6. Beaker 1 will be hypotonic because Diffusion Bag 1 has a less amount of sucrose concentration.
7. Beaker 2 will be hypotonic because Diffusion Bag 2 has a less amount of sucrose concentration.
8. Beaker 3 will be isotonic because Diffusion Bag 3 has the same amount of
sucrose concentration.
9. Beaker 4 will be hypertonic because Diffusion Bag 4 has less sucrose concentration.
My predictions are that:
10. Diffusion Bag and Beaker 1: Once diffusion has taken place, the mass will increase in the
bag and decrease in the beaker.
11. Diffusion Bag and Beaker 2: Once diffusion has taken place, the mass will increase in the bag
and decrease in the beaker.
This study source was downloaded by 100000832558064 from CourseHero.com on 04-28-2022 01:41:30 GMT -05:00
https://www.coursehero.com/file/35972247/Diffusion-and-Osmosisdocx/
