BIOL133 K010 Winter 2025
ESL Diffusion and Osmosis
Final Report
Student Name Timothy Hicks
Student ID 397832
Lesson ESL Diffusion and Osmosis
Institution American Public University
Session 777211
Course BIOL133 K010 Winter 2025
Instructor Tracey Woodlief
Exploration
Small, uncharged molecules can pass through the membrane via simple diffusion.
True
False
Exercise 1
Copyright 2025 - Science Interactive | https://scienceinteractive.com
, How did the blood cells appear in each of the different sodium
concentrations? What causes these differences in appearance?
Figure 5: Labeled Blood Smear
Isotonic Red Blood Cell: The cells remain biconcave in shape under normal conditions.
This is due to the fact that the osmotic pressure inside and outside the cell is the same,
with equal water movement.
Hypotonic Red Blood Cell: In this case, the cells are swollen or increased in size. This is
because water enters the cells to balance the raised concentration of solutes inside and
therefore swell.
Hypertonic Red Blood Cell: These cells appear crenated or shrunken. Water is lost from
the cells to the external solution to balance the higher external solute concentration.
Figure 6: Blood Cells in Distilled Water
The cells are swollen and may have burst. This is because the distilled water is
hypotonic; consequently, water rushes into the cells and causes them to swell up, even
to bursting.
Figure 7: Blood Cells in 0.9% NaCl Solution
Cells stay in their regular biconcave shape. The 0.9% NaCl solution is isotonic, so the
osmotic pressure is equal, and no net movement of water is possible.
Figure 8: Blood Cells in 12.5% Salt Solution
The cells are crenated and shrunken. The reason is that the 12.5% NaCl is hypertonic,
and water tends to leave the cells, thus causing shrinkage and wrinkling.
Word Limit
Is the movement of water in and out of these blood cells active or passive?
Water moves in and out of blood cells without energy being spent. This takes place by
osmosis, which is the movement of water through a membrane from an area with less
dissolved particles to an area with more dissolved particles. This movement does not
need energy and is based on the solute concentration difference inside and outside the
cell.
Word Limit
Why do intravenous (IV) solutions need to have the same tonicity as blood?
One is to avoid cell damage. An IV fluid that has less salt than the blood will make red
blood cells swell and can even burst. A solution with more salt, on the other hand, will
make cells shrink. Both of these situations can interfere with normal cell function.
Another important factor is the preservation of blood volume. Isotonic solutions will
preserve blood volume and pressure while replacing fluids, which is required for efficient
circulation and organ functionality.
In addition, matching the tonicity guarantees that fluid can be given without disrupting
the fine equilibrium between electrolytes and fluids in the body.
Finally, most medications given through IV need to be in an equilibrium state to work
efficiently and be absorbed by the body.
Word Limit
Copyright 2025 - Science Interactive | https://scienceinteractive.com
ESL Diffusion and Osmosis
Final Report
Student Name Timothy Hicks
Student ID 397832
Lesson ESL Diffusion and Osmosis
Institution American Public University
Session 777211
Course BIOL133 K010 Winter 2025
Instructor Tracey Woodlief
Exploration
Small, uncharged molecules can pass through the membrane via simple diffusion.
True
False
Exercise 1
Copyright 2025 - Science Interactive | https://scienceinteractive.com
, How did the blood cells appear in each of the different sodium
concentrations? What causes these differences in appearance?
Figure 5: Labeled Blood Smear
Isotonic Red Blood Cell: The cells remain biconcave in shape under normal conditions.
This is due to the fact that the osmotic pressure inside and outside the cell is the same,
with equal water movement.
Hypotonic Red Blood Cell: In this case, the cells are swollen or increased in size. This is
because water enters the cells to balance the raised concentration of solutes inside and
therefore swell.
Hypertonic Red Blood Cell: These cells appear crenated or shrunken. Water is lost from
the cells to the external solution to balance the higher external solute concentration.
Figure 6: Blood Cells in Distilled Water
The cells are swollen and may have burst. This is because the distilled water is
hypotonic; consequently, water rushes into the cells and causes them to swell up, even
to bursting.
Figure 7: Blood Cells in 0.9% NaCl Solution
Cells stay in their regular biconcave shape. The 0.9% NaCl solution is isotonic, so the
osmotic pressure is equal, and no net movement of water is possible.
Figure 8: Blood Cells in 12.5% Salt Solution
The cells are crenated and shrunken. The reason is that the 12.5% NaCl is hypertonic,
and water tends to leave the cells, thus causing shrinkage and wrinkling.
Word Limit
Is the movement of water in and out of these blood cells active or passive?
Water moves in and out of blood cells without energy being spent. This takes place by
osmosis, which is the movement of water through a membrane from an area with less
dissolved particles to an area with more dissolved particles. This movement does not
need energy and is based on the solute concentration difference inside and outside the
cell.
Word Limit
Why do intravenous (IV) solutions need to have the same tonicity as blood?
One is to avoid cell damage. An IV fluid that has less salt than the blood will make red
blood cells swell and can even burst. A solution with more salt, on the other hand, will
make cells shrink. Both of these situations can interfere with normal cell function.
Another important factor is the preservation of blood volume. Isotonic solutions will
preserve blood volume and pressure while replacing fluids, which is required for efficient
circulation and organ functionality.
In addition, matching the tonicity guarantees that fluid can be given without disrupting
the fine equilibrium between electrolytes and fluids in the body.
Finally, most medications given through IV need to be in an equilibrium state to work
efficiently and be absorbed by the body.
Word Limit
Copyright 2025 - Science Interactive | https://scienceinteractive.com
