Maria Faye Stephanie Cantago January
The transport of
molecules inside and outside of the cell requires a complicated system to be as
efficient as possible. This transport system comprises the passive and active
transport of molecules. In the experiment, the type of transport tackled is the
passive transport without the use of energy or ATP. Some of the results followed
the standard results of the experiment, with the exception of some tests in the
dialysis which maybe due to the remaining fate tissues inside the dialyzing
membrane. This is also true to the human body’s transport system which becomes
less efficient when it is blocked by fats. In conclusion, cell to cell
transport is very important for the continuous function of the cells, tissues,
organs and the body in general.
of gas in a Gas
Graham (1829), equal volumes of different gases diffuse in very unequal times
which also has an inverse relation to the specific gravity of the gas and its
density. Furthermore, the vapor or gas will be propagated to any distance, by
exchanging positions with a train of particles of air, according to the law of diffusion.
The length, to which this diffusion proceeds, in a confined portion of air, is
limited by a property of vapor, namely, that the particles of any vapor
condense when they approximate within a certain distance (Wisniak, 2013).
min 39 secs
2 mins 5 secs
3 mins 38 secs
4 mins 56 secs
1. Rate of diffusion of perfume in a close room.
The material used in the experiment
is a perfume placed in a petri dish and was left to evaporate and diffuse in a
close room. The different distances covered by the experimenters were one to
five meters. The result was obtained by how long will the gas take to diffuse
in the air and reach the experimenters olfactory system.
When the perfume
evaporated and diffused, there was no outside air to help it spread faster
across the room. The farther the student was from the perfume, that longer the
time it took for the student to smell the perfume (Table 1). As the molecules
of the perfume slowly travel across the room, it moves randomly, bumping the
air molecules in the room and made the travel of the gas to the experiments
olfactory system to be longer.
of a Solid in a Colloidal Solution
The diffusion of solids has the slowest
rate, however, this depends on the interaction of the solid to its medium (“Why
does diffusion take place”, 2016). The diffusion rate of solid is also affected
by the weight of the solid. As the molecular weight increases, rate of
diffusion decreases. Another thing that can affect the rate of diffusion is the
temperature (“Why does diffusion take place”, 2016). As the temperature
increases, the rate of diffusion also increases.
Figure 1. Graph of the diffusion rate of solids
in a colloidal solution.
Table 2. Diffusion rate of different solids in a colloidal
Potassium permanganate (158g/mol)
0.402 mm/ min
Methylene blue (327g/mol)
0.016 mm/ min
Potassium dichromate (294g/mol)
0.225 mm/ min
the experiment, potassium permanganate, with a molecular weight of 158 g/mole,
has the highest average rate of diffusion. This is followed by potassium
dichromate, having a molecular weight off 294 g/mole, and methylene blue, with
374 g/mole molecular weight. The trend indicates that the lower the molecular
weight of a substance, the faster it diffuses in the agar (Table 2 and Fig. 1).
Thus, confirming that the rate of diffusion of a substance is affected by its
of a Solid in a Liquid
The diffusion of solid in the liquid
medium involves a separation of solute from the surface of the solid and the
disintegration of the solute molecules into the liquid phase (Hsu and Liu,
1993). The diffusion rate of solid in liquid is relatively faster compared to
the diffusion of solid in a colloidal surface. Other factors that may affect
the diffusion rate of solid are temperature, mass and size of the particle.
Figure 2. Potassium permanganate crystal slowly diffusing in
In the experiment, potassium
permanganate was used as the solid that diffused in the liquid medium which is
water. The potassium permanganate crystal slowly dissolved in the bottom of the
beaker and starts to diffuse. This process is called dissolution which is due
to the diffusion of the solid particles. After 30 minutes, the potassium
permanganate, the purple dye (Fig. 2), finally covered the bottom part of the
beaker. Furthermore, the size of the potassium permanganate crystals also
affected the rate of the diffusion since the larger the surface area, the
faster the diffusion rate (“Study of Diffusion of Solids in Liquids”, 2015).
Osmosis is a type of passive transport
of water molecules across a semi-permeable membrane following the concentration
gradient of the solute. It can happen during a) two solutions are separated by
a water permeable membrane but impermeable to at least one of the solutes in
the solution and b) the total concentration of impermeable solutes between the
two solutions inside and outside the membrane is different (Finkler, n.d.).
Table 3. Weight of the
diffusing membranes with NaCl and distilled water every 5 minutes.
filled membrane in water solution
filled membrane in NaCl solution
After 5 mins
After 10 mins
After 15 mins
After 20 mins
After 25 mins
In the experiment, pig intestines were
used as dialyzing membrane to imitate the function of the plasma membrane. The
NaCl filled dialyzing membrane absorbed water from the water solution at the
start of the experiment while the water filled dialyzing membrane lost its
water to the NaCl solution. However, as the osmosis continues for 30 minutes,
the rate of the two set-ups decreased as the solution outside and inside the
dialyzing membranes slowly reaches equilibrium. A notable inconstant decrease of
the weight was observed in the water filled membrane which may be caused by the
attempt of the membrane to reach equilibrium.
Hemolysis and Crenation
The net movement
of water in and out of the cell is driven by the difference in osmotic pressure
between the extracellular and intracellular fluids (Finkler, n.d.). Thus, the
extracellular fluid has an important role to the cell. The effect of the
extracellular fluid to the cell is called tonicity (Finkler, n.d.). It can be
isotonic which means that the osmotic concentration of the extracellular fluid
is the same with that of the fluid inside the cell. Hypotonic, which means that
the osmotic concentration of the extracellular fluid is lower than that of the
cell and hypertonic if the extracellular fluid is higher than that of the cell.
3. Illustration of red blood cells when exposed to (A) distilled water, (B)
0.9% NaCl and (C) 3% NaCl.
microscope, the red blood cells from the solution with distilled water swelled
and burst (Figure 3.A). This is because the osmotic concentration outside the
cell is lower than that of the inside of the cell, the water tends to move
inside the cell. In the solution with
0.9% NaCl, there was no apparent change to the red blood cells (Figure 3. B)
because the osmotic concentrations inside and outside the cell are equal so the
net movement of water is zero. Lastly, the red blood cells of the solution
containing 3.0% NaCl shriveled (Figure 3.C). This is because the osmotic
concentration of the extracellular fluid is higher than that of the cell’s
fluid, the water tends to go outside the cell.
membrane is used to mimic the function of the kidney to filter the blood and
transport it to the different organs of the body. These membranes allow only
specific molecules to pass through such as low molecular weight molecules while
blocking other large molecules such as proteins and albumin (To et al, 2015).
experiment, the researchers obtained a piece of dialyzing membrane. This was
then filled with a solution composed of 1%boiled starch, a pinch of sodium
chloride, 20mL glucose and small albumin. The dialyzing membrane was immersed
in a beaker filled with distilled water. After 30 minutes, the water outside
the dialyzing membrane was tested for the following:
A. Test for sodium chloride
4. Solution after the addition of silver nitrate.
The solution is
colorless. The absence of any precipitate indicates a negative result for the test
for sodium chloride. Supposedly, the small molecules and ions (Na+,
Cl-) should have pass out the surrounding solution which would give
a positive result for the sodium chloride test (Shreya, n.d.). The negative
result could have been caused by the remaining fats surrounding the intestine
which could have blocked the passage.
B. Test for starch
5. Solution after the addition of IKI.
The solution is
colored reddish brown, which is the color of the IKI. The absence of any
blue-black color in the solution indicates a negative result for the test for
starch. This is because the starch molecules are too large to pass through the
membrane thus remaining inside the intestine (Selective Permeability &
6. Solution after the addition of Benedict’s solution.
The solution is light
blue, which is the color of Benedict’s solution. The absence of any precipitate
even after the boiling of the solution in a water bath indicates a negative
result for the test for glucose. Supposedly, glucose has small molecules that
can pass through the membrane which would then give a positive test result
(Selective Permeability & Dialysis, n.d.). The negative result could have
been due to the remaining fats surrounding the intestine which could prevent
the passage of molecules.
Figure 7. Solution after the
addition of concentrated nitric acid.
The solution was
colorless which also lacked any precipitate, indicating a negative test result
for albumin. Albumin is made up of proteins that has molecules that are too big
to pass through the membrane. Thus, they are only present inside the membrane
(Selective Permeability & Dialysis, n.d.).
are different types of cell membrane transport which allows specific molecules
to pass through. This kind of transport system works for the cells and the body
because the restrictions of some molecules makes the function of the plasma membrane
and the cells to be more efficient.
(n.d.) Osmosis, Tonicity, and Concentration. Indiana
Science, Mathematics, and Informatics Department http://www.indiana.edu/~nimsmsf/
Graham T., (1829). A Short Account of Experimental Researches on
the Diffusion of Gases Through Each Other, and their Separation by Mechanical
Means. Quart. J. Sci., 2, pp. 74-83
Hsu, J. and Liu, B. (1993). Dissolution
of solid particles in liquids: A reaction—diffusion model. Colloids and
Surfaces, 69(4), pp.229-238.
Adv. Colloid. Interface Sci.. 14. pp 239.
Selective Permeability &
Dialysis. n.d. Bio662.dyndns.info.
n.d. Experiment on Dialysis (With Diagram) | Physics. online Biology
Diffusion of Solids in Liquids | Chemistry Science Fair Project. (2015).
To, N., Sanada, I., Ito, H., Prihandana, G., Morita,
S., Kanno, Y. and Miki, N. (2015). Water-Permeable Dialysis Membranes for
Multi-Layered Microdialysis System. Frontiers in Bioengineering and
Wisniak, J. (2013). Thomas Graham. II. Contributions to
diffusion of gases and liquids, colloids, dialysis, and osmosis. Educación
Química, 24, pp.506-515.
diffusion take place. (2016). A plus topper. https://www.aplustopper.com/diffusion/