Osmosis and Diffusion Lab Using Potato Cores Lab

7/29/2019 Osmosis and Diffusion Lab Using Potato Cores Lab

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Osmosis and Diffusion Lab using Potato Cores

Instructions and Rubric

Cindy Shin

Biology 4BResearch Question

Will there be any differences in the movement of water in or out of a set ofpotato cores depending on the different concentrations of sucrose?

Introduction In this lab, we put a set of potato into six cups with different amount of sugar

mixed with water. The purpose of this lab was to see how the materials move

in and out of the potato according to the difference in concentration; materials

always move from high concentration area to low concentration area. As water

couldnt move in and out by itself, the transport that was used in this process

is called facilitated transport: Facilitated transport is where the protein channelhelps the movement of materials through the membrane, because they cant

get through by themselves. In conclusion, we observed how the water moves

in and out of the potato according to the concentration on either side of the

membrane.

Hypothesis If the concentration of the sugar in the water is larger, then the set of potato in

the cups is going to get bigger.

Variable Identified Independent Variable: The concentrations of sucrose in each cup Dependent Variable: The size of the set of potato Controlled Variable: The potatoes that are being used and the time spent

after putting the potatoes in the cups

Materials You will be working in groups of 4 if at all possible to share the work load (2

buddy groups)

Potato cores (4 per condition) Sucrose solutions (.2, .4, .6, .8, 1.0) Distilled water Electronic balance Plastic weighing tray Plastic cups (6) Graduated cylinder (50 ml) Scalpel Marking tape Blue tweezers

Procedures Using marking tape, label 6 cups with

the following solution types (.2, .4, .6,

.8, 1.0 and Di water)

Place approximately 50 ml of thevarious solutions, each cup receiving a

separate solution. Suggestion,


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measure the Di water with the graduated cylinder, and fill the other cups to the

same level

Obtain 24 potato cores and cut them to equal sizes (about 2.5 cm). All thecores you use must be the same length

Divide your 24 cores into 6 groups and gently blot them dry with a papertowel Using the electronic balance and plastic weighing tray mass (weigh) each

group of potato cores and record the data in a table that is labeled with a

detailed title and which provides the error measurement of the electronic scale.

MAKE SURE TO TARE THE TRAY. The table should record the type of

solution in the cup and the mass of the potatoes in the cup.

Place the potato core sets in their appropriate cup and place in Mr. Boyersback prep room in the fume hood that is labeled with your block (3B or 4B).

PS make sure to indicate on your cup your group number, Mr. Boyer willassign group numbers during the lab

24 hours later (app) you will need to come and measure the mass of yourpotato cores. To do this you must pore off

the fluid in the cup and use the plastic

blue tweezers remove the cores, blot them

dry just as you did in the set up phase and

final measure them using a plastic

weighing tray. MAKE SURE TO TARE

THE TRAY. Record your potato group

mass on your data chart.

Finally dump your potato cores in thetrash and wash and dry your equipment

(cups, tweezers and return them to their stations


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Calculations. For each setup (all 6) you will need to calculate a percent masschange. To do this you will use the following formula (final mass-initial

mass)/initial mass x 100. You will need to record this data in your data table

as well. Make sure to keep track of the positive and negative changes if they

occur

Data Chart

Initial Mass Final Mass Formula Mass

Change

Water 2.4g 2.6g (2.6-2.4)/2.4 * 100 8.3%

Sucrose 0.2 2.4g 2.7g (2.7-2.4)/2.4 * 100 12.5%

Sucrose 0.4 2.4g 2.3g (2.3-2.4)/2.4 * 100 -4.2%

Sucrose 0.6 2.4g 1.9g (1.9-2.4)/2.4 * 100 -20.8%

Sucrose 0.8 2.4g 1.8g (1.8-2.4)/2.4 * 100 -25%

Sucrose 1.0 2.4g 1.4g (1.4-2.4)/2.4 * 100 -41.7%

Formula: Final mass initial mass/initial mass) * 100 = % mass change Error measurement for all the masses measured is 0.05g. Error measurement for all the percent calculation is 0.05%.

Graph of the Results

This is the graph that shows percents of mass change in potatoes verses thesucrose concentration. The slope is negative, which shows that the percent of

the mass change decreases while the sucrose concentration increases. The line

drawn on the graph is the best-fit line, which shows the approximate slope of

the data; the x-intercept of the best-fit line represents the water potential of thepotato cores.

50

40

30

20

10

0

10

20

0 0.2 0.4 0.6 0.8 1 1.2

%M

asschange

Concentration

% Mass change vs. concentration


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Conclusions

Looking at the results that I have observed, I can see that the mass of thepotatoes increased while the concentration of the sucrose decreased. This

shows that the higher the concentration of the sucrose is in the water, the more

water is released from the potatoes. The fact that the water has more sucrose in

them tells us that there is less water in the cup; as there is not enough water in

the cup, the water from potatoes has to come out to make the concentration the

same across the membrane. Materials move from higher concentrated area to

lower concentrated area. Since the sucrose concentrations increased, the

potatoes released more water from themselves.

The best-fit line in the graph touches the x-axis at 0.28. This point indicates

the water potential of the potato cores.

This graph is the data of mass change according to the sucrose concentrations

from each four group. The graph shows that all the x-intercept from four

groups is about 0.26 to 0.29. The difference of the solute concentrations inside

the cores might have occurred of several reasons. One of the reasons is that

some of the groups might not have measured the mass of the potatoes

correctly after taking them out of the sucrose water; they might not have dried

the potatoes completely before putting them on the weigh. In conclusion, the

graph shows that the water potential of the potato cores is fairly the same for

all the groups: about 0.26 to 0.29.

100%

80%

60%

40%

20%

0%

20%

40%

60%

80%

SC 0 SC 0.2 SC 0.4 SC 0.6 SC 0.8 SC 1

Percentof

MassChange

Sugar Concentration

Sugar Concentration vs. Percent of Mass

Change

% of Mass Change G4

% of Mass Change G3

% of Mass Change G2

% of Mass Change G1


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Evaluation/Reflection This lab was pretty easy to accomplish, because all we had to do was to put

the set of potato in six cups of different sucrose concentration and to wait for a

day, and collect data from that.

In the beginning of the lab, cutting the potatoes into the same sizes was asuccess to our group, because we ended up with having the same mass for all

the potatoes.

During the lab, we didnt have that many difficulties. However, one difficulty

that occur during the lab was that collecting data the next day. After taking the

potatoes out of the six cups, we had to dry them before weighing their mass;

this process was challenging because the data wouldnt be as accurate if the

potatoes are perfectly dried. So below the chart that I made, I wrote the error

measurements for the masses that have been weighed.

Through this lab, I learned that the materials move from higher concentrated

area to lower concentrated area. Before I did this lab, I was confused how the

concentration affects the movements of the materials, and also, how the

materials get into or out of the membrane. After accomplishing the lab, those

concepts became clear and were easier to understand than before.

If I have an opportunity to do this lab again in the future, I would like to

enhance my work by collecting data as accurate as possible, so that there

wouldnt be any differences compare to the other groups. During this lab, not

all the group members had chance to look at the results of the mass change in

potatoes, because only a few people went to check the potatoes during lunchtime. So if I could, I would like to observe the results more carefully with

more accurate data.

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Osmosis and Diffusion Lab Using Potato Cores Lab