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The Effect of Solute Concentration (Glucose and NaCl) on Osmolarity in
Solanum tuberosum (Russet Potato) Cells
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Introduction
Ever since I was a little kid, I loved going to my grandma's house for her famous mashed potatos
dish
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She said it would make them mushy or tough, depending on the type of
solution
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Later in science class, I learned about osmosis and how water moves in and out of cells
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I got inspired to
test this idea out
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I wanted to see if I could take this basic cooking tip I learned growing up and get some
hard data on how osmolarity impacts potato cell osmosis
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Even the simplest kitchen
skills can connect back to the world of science in cool ways
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Research Question
"How do the osmolarity levels of Solanum tuberosum (Russet Potato) cells change when
exposed to sodium chloride (NaCl) and glucose solutions at concentrations of 0
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1M,
0
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3M, 0
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5M, respectively?"

3
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This movement of solvent molecules through selective membrane channels
seeks to solute concentrations on both sides
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On one side is pure water, creating
a hypotonic solution, while on the other is a concentrated
chocolate solution, forming a hypertonic solution
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Driven by this
concentration gradient, with lower solute concentration on
Figure 1
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This net flow
continues until equilibrium is achieved, analogous to how water
enters plant or animal cells
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The selectivity of cellular membranes provides the basis for osmotic flow
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The phospholipid tails are hydrophobic and would not permit water flow without these
2

integral proteins
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Osmosis regulates cellular turgor pressure,
maintains hydration, absorbs nutrients, and eliminates wastes by virtue of these channels
within the semi-permeable membrane (BioLibretext, 2023)
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But when you look
closer, you realize plant cells have some totally unique structures not found in animal cells
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One big difference is the plant cell wall, that rigid box
around the cell membrane
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The primary cell
wall is composed of intersecting cellulose and
hemicellulose microfibrils, along with strands of pectin and
some soluble proteins (BioLibretext, 2023)
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It's made of cellulose, which you won't find in an
animal cell
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(LadyofHats, via Wikimedia
Commons)

Plants also have a huge central vacuole taking up most of the
cell's interior
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When the plant is under-watered, the vacuole shrinks as water leaves the cell
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So, while animal cells
have tiny vacuoles, this central water-filled vacuole is a definitive plant cell feature
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In preparation for discussing osmolarity, it is imperative to clarify some essential units of
measurement that are foundational to the topic
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022x10²³ particles—reflecting the quantity of atoms in 12 grams of carbon-12,
which serves as a universal metric in chemistry for quantifying substances
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In the context of
osmolarity, we shift our focus to osmoles, which account for the number of particles that are
available to exert osmotic pressure, particularly when a solute such as sodium chloride
dissociates in solution
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This distinction is
crucial for accurately approaching osmolarity, which measures the total solute concentration
in terms of its osmotic impact
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Osmolarity is a fundamental concept in biology, particularly in understanding the delicate
balance between cells and their surrounding environment
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Imagine a bustling dance floor
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The more dancers there are, the more crowded the floor
becomes, and the harder it is for water molecules (think partygoers) to move around freely
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936)
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Here's why: as mentioned before, water balance cells need a steady flow of water for
various functions, like nutrient transport, waste removal, and maintaining their shape;
osmolarity dictates the direction of this flow
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Disruptions in osmolarity can alter their
structure and activity, hindering vital cellular functions
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936)
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Conductivity meters measure
the electrical conductivity of a solution, which can be an indirect indicator of osmolarity for
certain types of solutions
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For solutions with known solute concentrations, osmolarity
can be estimated using specific formulas based on the individual contributions of different
solutes (Rasouli, 2016, p
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𝑂𝑠𝑚𝑜𝑙𝑎𝑟𝑖𝑡𝑦 = 𝛴(𝑛𝑖 × 𝐶𝑖)
This is the general formula used to calculate osmolarity, where “𝑛𝑖" represents the number of
particles into which each solute “i” dissociate, and “𝐶𝑖" is the molarity of each solute
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0

0
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0

0
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2

0
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2

0
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2

0
...
6

0
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4

0
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4

0
...
0

0
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01: osmolarity of NaCl and glucose

In table
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As previously mentioned NaCl
dissociates into two ions 𝑁𝑎+ 𝑎𝑛𝑑 𝐶𝑙− which; therefore, doubles their osmolarity
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Having taken these results into account, I came up with two hypotheses:
1
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2
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4
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Prepare solutions with NaCl and glucose at concentrations of 0
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1, 0
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3, 0
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5 moles/liter
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Cut potato tissue into samples with dimensions of 1x1x5 centimeters to ensure
uniformity
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Weigh each sample using an electronic balance to record initial masses
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Immerse the samples in the solutions for 60 minutes to allow for osmotic balance to
occur
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After immersion, remove, blot dry the samples to remove excess solution, and weigh
again for final mass determination
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Calculate percentage mass change for each sample using the formula:
%𝑐ℎ𝑎𝑛𝑔𝑒 =

(𝑓𝑖𝑛𝑎𝑙 𝑚𝑎𝑠𝑠 − 𝑖𝑛𝑖𝑡𝑖𝑎𝑙 𝑚𝑎𝑠𝑠)
× 100
𝑖𝑛𝑖𝑡𝑖𝑎𝑙 𝑚𝑎𝑠𝑠

7
...

8
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9
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10
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11
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5

Variable type
Independent
Independent

Variable
Concentration of NaCl
solution
Concentration of glucose
solution

Dependent

% mass change of potato
samples

Control

Size and shape of potato

Control

Temperature

Control

Duration of immersion

Control

Number of trials

Control

pH

Manipulation/ Reason
Varied to observe the effect
on osmosis
Varied to observe the effect
on osmosis
Measured to determine the
extent of osmosis due to
solution concentration
Kept constant to ensure
uniformity across samples
Kept constant to prevent its
effect on the rate of osmosis
Kept constant to allow equal
time for osmosis in all
samples
Repeated to ensure
consistency and reliability of
data
It can impact the potato
cells' membrane stability and
p

0
...
4

0
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6

0
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6

8
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0

15
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5

12
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5

2
...
3

0
...
3

0
...
3

2
...
0

75

2
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0

4
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33

0
...
0

0
...
1

-0
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1

0
...
0

2
...
5

2
...
4

1
...
5

-0
...
2

-0
...
3

-0
...
0

-5
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5

-7
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0

-6
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54

Table
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Specifically, I used the standard deviation formula to
quantify the spread of my experimental results, enhancing the reliability and precision
analysis of the outcomes in a non-standard laboratory setting
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At 0
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56, which
demonstrates a modest variation in the osmotic behavior of the potato sticks in distilled water
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With increasing
salt concentrations, the standard deviation values trend lower, culminating in a standard
deviation of 1
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5 M NaCl
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The data suggests that the osmotic effects induced by NaCl on the potato sticks are
more uniform with higher salt concentrations, leading to a more homogeneous response
across the trials
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DATA COLLECTION AND PROCESSING (GLUCOSE)
This the data collected from the experiment with glucose solutions with varying
concentrations as shown in the following picture:

figure
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0

5
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0

4
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0

5
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9

5
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8

4
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8

Mildly
swollen

0
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4

4
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2

5
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4

Inconsistently
altered

0
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3

4
...
1

5
...
3

Inconsistently
altered

0
...
1

4
...
1

5
...
1

Inconsistently
altered

0
...
0

3
...
0

5
...
1

Inconsistently
altered

0
...
9

3
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9

4
...
0

Slightly
reduced

Table
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Here are my results:

Change in mass
Percentage change in mass
Concentrati
on of
Trial Trial Trial Trial Trial Trial Trial Trial Trial Trial
Glucose
Solution
1
2
3
4
5
1
2
3
4
5
(M)

Average
percentage
change in
mass

Standard
deviation

0
...
9

1
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8

0
...
8

18
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0

20
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5

16
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3

3
...
1

0
...
2

0
...
3

0
...
0

5
...
0

6
...
0

7
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32

0
...
3

0
...
1

0
...
3

7
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5

2
...
0

7
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8

2
...
3

0
...
1

0
...
1

0
...
5

2
...
5

2
...
5

2
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22

0
...
0

-0
...
0

0
...
1

0
...
5

0
...
0

2
...
0

1
...
5

-0
...
1

-0
...
2

0
...
5

-2
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5

-4
...
0

-2
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44

Table
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At 0
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56, we
see the greatest variability in the potato sticks' responses, possibly due to their differential
absorption of water in a hypotonic environment
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1 M, the
standard deviation decreases to 2

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