The Effect of Water and Sucrose Solution on Plant Tissue

I am going to investigate the change in size and weight of a potato
when bathed in the water, dilute sugar solution and concentrated
sucrose. This investigation will take place under the Osmosis theory.
Osmosis will cause the water molecules to travel in and out of the
plant cell.
Aim:

To investigate the effect of varying concentration of a certain sugar
solutions on the amount of osmotic activity between the solution and a
potato chip of a given size.

Method

? First we are going to collect 6 boiling tubes each containing a
concentration of sugar solution between 0.0, 0.2, 0.4, 0.6, 0.8 and
1.0 Mol DM -3.

? We will then get a Cork borer of size 3; we will then insert it
through the potato so we could achieve our cylindrical shape.

? We will then measure out the potato samples to 3cm using the Vernier
callipers. We will cut the potato samples for fine adjustment.

? We will then weigh the potato samples using the electronic weighing
scales.

? We will then place the 18 potato samples in the test tubes each
containing the different type of solutions. We will have two test
tubes for each amount of mol. Each test tube will contain 3 potato
samples.

? We will then leave the potato samples in the solutions for about
half an hour. We will use one test tube for each Mol DM -3 which
increases by 0.2 each time and then get an average.

? We will then measure and weigh each of the potato samples. We will
then record the differences onto a table of results.

Equipments list

? Scalpel

? Cork borer

? 6 Test tubes

? Test tube rack

? Potato

? Vernier callipers

? Sugar solution

? Chopping board

? Water solution

? Weighing scales

Why?

? We will use a scalpel to cut the potato to the required length

? We will use a cork borer to collect our potato samples in a
cylindrical shape.

? We will get 6 test tubes because each test tube will contain 3
potato samples and a recorded concentration of solution.

? We will collect a test tube rack so we can place the test tubes
inside it.

? I will use a potato to collect my samples because it's a plant and
it's what we were asked to investigate.

? We will use vernier callipers to measure the potato samples so we
could measure them to two decimal places.

? We will use different concentrations of sugar solution so we can
investigate the changes between different concentrations.

? I will use a weighing scale to measure the weight of the potato
samples accurately before and after the investigation.

To make this experiment as productive as possible I will be varying
the concentration of the sucrose. The concentration of sucrose will
vary from 0.0. to 1.0 Mol DM -3.

To make this experiment as accurate as possible, I am going to collect
two types of results and then achieving the average. I am also going
to use vernier capillaries which will give me results to 2 decimal
places which will keep the measurements as accurate as possible. In
order of keeping the weights as accurate as possible I will be using
electrical weighing scales.

I am going to do the following things in order to make this experiment
a fair test:

? For the purpose of my experiment I am going to do all the
experiments at room temperature.

? the water potential of the potato initially will be kept the same by
using the same type of potato, which have been treated in the same
way, e.g. have all been cut without being washed and peeled.

? The mass of the potato is a dependent variable, and this means that
it will be measured throughout the experiment. I will measure the mass
in grams. The potato chip will be measured before it is put in the
solution, and after. This will allow us to see whether osmosis has
taken place, and to what extent.

? The volume of the solution that the potato chips are kept in must be
fair. The must be totally covered in the solution, and the amount of
solution will be kept the same because all the potato chips are
roughly same size.

? I am also going to use the same balance to weigh my potato chips.
This is because the measurements may slightly vary between scales. We
used an electronic scale for highest accuracy.

? I am going to use the same type of potato for every single sample.

? The same person in my group will be doing the measuring and a
different person will be doing all the weighing before and after the
experiment.

? The same member of my group will measure out the solutions in the
test tube.

Once I have completed the experiment I will be measuring and weighing
the potato samples, I will see if the potato samples have increased or
decreased in weight or size depending on the concentrations of sucrose
and water. I will also be investigating my results to see if they
support the theory of osmosis.

Osmosis theory

Osmosis is a special type of diffusion. It is the movement of water
through a partially permeable membrane. Suppose water is separated
from a sugar solution by a membrane which is permeable to water
molecules, but impermeable to sugar molecules. The pure water will
have a high concentration of water molecules, whereas the sugar
solution will contain low concentration of water molecules. Therefore
the water molecules will then diffuse through the partially permeable
membrane from the region of high water concentration to a region of
low water concentration. This will result in even distribution.

High concentration of water Low concentration of water Molecules
Molecules

[IMAGE]

The diagram shows us the diffusion theory for osmosis. As you can see
the water molecules are leaving the region of high concentration of
water molecules (dilute solution) and are entering the region of low
concentration of water molecules (strong solution) through the
partially permeable membrane. Osmosis will only occur provided a weak
solution is separated from a strong solution by a partially permeable
membrane. Some sugar molecules do pass through pores but at a much
slower rate.

The diagram below shows the result of the plant cell after the osmosis
has taken place when it has been placed in different solutions.

[IMAGE]

The picture above shows us the result of a cell when water enters
through the partially permeable membrane. The diagram on the right
which is labelled Turged shows us the cell when a more dilute mixture
(water) enters the cell. The water diffuses through the freely
permeable cell wall and selectively permeable membrane and enters the
vacuole. The vacuole swells and pushes the cytoplasm against the cell
wall.

On the other side of the diagram we are shown what happens when the
cell is bathed in a strong solution. The water leaves the cell by
osmosis, the vacuole shrinks and the cytoplasm is pulled away from the
cell wall. The cell in this condition is said to be Plasmotised. The
sugar solution enters the space between the cell wall and cytoplasm.

A dilute solution will have a higher water potential than a
concentrated solution. In the textbook GCSE Biology by D.G.Mackean it
says 'The water potential of a solution is a measure of whether it is
likely to lose or gain water molecules from another solution. Pure
water has the highest possible water potential because water molecules
will flow it to any other aqueous solution, no matter how dilute.'

The scientific knowledge supports my prediction that the more dilute
solutions will enter the cell and cause it to swell and become turged.
Whereas the more concentrated solutions will cause the cytoplasm to
shrink away from the cell wall and become plasmotised.

We carried out a preliminary experiment before in class to help us
with our actual experiment. The preliminary experiment helped us
decide what size cork borer to use. It showed us what size was the
best for gaining good results at minimum time. It also helped decide
how long the potato cylinder would be. We used a potato in our
preliminary experiment so we could test whether a potato would give us
accurate results. This experiment also gave us practise on how to use
the vernier callipers. This made sure that the length of our potatoes
was accurate. The preliminary experiment helped us decide what a
suitable time was to keep the potato samples in the solution, in order
there is a significant change in the size and length of the potatoes
so we gain outstanding results.

RESULTS TABLE FOR THE CHANGE IN MASS

Concentration of sucrose 1.0 MDM -3 each test tube had 3 samples

total Mass before**

Total Mass after**

0

6.40g

6.46g

Average of titles**

2.133g

2.1533g

Ave % inc/dec

Before investigation 0%

0.92% inc

0.2

6.26g

6.36g

Average of titles**

2.0866g

2.12g

Ave % inc/dec

Before investigation 0%

1.5977% inc

0.4

6.28g

6.49g

Average of titles **

2.0933g

2.1633g

Ave % inc/dec

Before investigation 0%

3.32804% inc

0.6

6.20g

5.68g

Average of titles**

2.0666g

1.893g

Ave % inc/dec

Before investigation 0%

8.796% dec

0.8

6.22g

5.62g

Average of titles**

2.0733g

1.873g

Ave % inc/dec

Before investigation 0%

9.662% dec

1.0

6.35g

5.66g

Average of titles**

2.11666g

1.886667g

Ave % inc/dec

Before investigation 0%

10.8966% dec

RESULTS TABLE FOR THE CHANGE IN LENGTH

Concentration of sucrose 1.0 MDM -3 each test tube had 3 samples

Length before**

Length after**

0

133.5mm

135.3mm

Average of titles**

44.5mm

45.1mm

Ave % inc/dec

Before investigation 0%

1.348% inc

0.2

135.6mm

136mm

Average of titles**

45.2mm

45.3333mm

Ave % inc/dec

Before investigation 0%

0.29498% inc

0.4

134.4mm

134.6mm

Average of titles**

44.8mm

44.8666mm

Ave % inc/dec

Before investigation 0%

0.148809508%inc

0.6

131.6mm

128.8mm

Average of titles**

43.8666mm

42.93333mm

Ave % inc/dec

Before investigation 0%

2.127659649% dec

0.8

132.8mm

130.4mm

Average of titles**

44.2666mm

43.466667mm

Ave % inc/dec

Before investigation 0%

1.8072% dec

1.0

138.6mm

135.3mm

Average of titles**

46.2mm

45.1mm

Ave % inc/dec

Before investigation 0%

2.30895% dec

All of my results that were gained were all correct to 2 decimal
places. The mass of my results were found out using an electrical
weighing scale, the mass was measured using grams. To work out the
length of the potato samples we used vernier callipers, the length was
measured using millimetres. In order my results were accurate I gained
three sets of results and then got an average. To work out any changes
in any of the potato samples we worked them out using percentages.

I have found from my results that the when there was an increase in
the concentration of the sucrose solution there would be a decrease in
the mass and length of the potato sample. The higher the concentration
of the sucrose solution the more decrease there is in the mass and
length of the potato samples. When the concentration of sucrose
solution reaches about 0.6 Mol DM -3 the mass and length of the potato
samples decrease.

These results support my hypothesis.

CONCLUSION

From this investigation I have found that the higher concentration of
sucrose solution in the test tubes, the lower the mass and length of
the plant cell. This is because when the cell is bathed in a
concentrated solution the water leaves the cell by osmosis, the
vacuole shrinks and the cytoplasm is pulled away from the cell wall.
The cell in this condition is said to be Plasmotised. The sugar
solution enters the space between the cell wall and cytoplasm. The
cell decreases in volume and length. This happened when the cell was
bathed in sucrose solution which had a concentration of 0.6 Mol DM -3
or higher.

When the cell was bathed in a sucrose solution of concentration 0.4
Mol DM -3 there was an increase in the mass and length of the plant
cell. When a cell is bathed in a more dilute solution it increases in
size and it's said to have become Turged. This is because when water
diffuses through the freely permeable cell wall and selectively
permeable membrane it enters the vacuole. The vacuole swells and
pushes the cytoplasm against the cell wall. This results in the
increase of size.

From my graph (next page) I have found a reasonable pattern which
supports my prediction and osmosis theory. It appears that the line of
best fit is decreasing as the concentration of sucrose solution
increases (x axis). Which points out that length and mass of the
potato samples (y axis) must be decreasing. Due to the osmosis effect
of plasmosis.

My conclusion does support my previous prediction that the more dilute
solutions will enter the cell and cause it to swell and become Turged.
Whereas the more concentrated solutions will cause the cytoplasm to
shrink away from the cell wall and become Plasmotised. The potato
samples that were in the test tubes that contained the sucrose
solution of concentration 0.4 Mol DM -3 or less had increased in mass
and length.

On the other hand the potato samples that were in the test tubes which
contained the sucrose solution of concentration 0.6 Mol DM -3 or more
had decreased in mass and length.

EVALUATION

I think my investigation went pretty well. I am very pleased with the
results I gained because they had shown me a good trend/pattern which
I could refer to.

My graphs showed me a good set of results which I really expected.
Both graphs had a curve of best fit decreasing which represented the
results gained. The graphs had curves travelling downwards which I
pretty much expected, because as the concentration increased the
change decreased which meant that the curve would travel downwards and
across. There was one or two anomalous gained from my graph, this
might have been because of the human errors in measuring and weighing.

I think the procedure I used was quite suitable for this experiment
because there was quiet a lot of variation in the concentration of the
sucrose solution. I varied my sucrose concentration from 0.2 to 1.0
Mol DM -3 which gave us results which covered most solutions. For each
concentration I investigated I used one boiling tube with three potato
samples inside so I could get an average which would give me accurate
results. To measure my potato samples I used the vernier callipers
which would measure the samples to 2 decimal places which gave me
accurate measurements. I also used the electrical weighing scales to
weigh my potato samples which improved the accuracy.

I could have improved the procedure of the experiment by having more
test tubes for each concentration and an increased number of
concentrations then I would be able to get more accurate and an
enhanced range of results. I could have left my experiment under
observation for a longer time (over an hour) to see further
differences in length and weight.

There were not any out of the ordinary results, but some were not as
close to the line as others. This may have been caused by human error.
When the potato chips were removed from the test tubes and dried I may
well have dried some potatoes more thoroughly than others and so some
would have more excess water, which would add to the mass. If the
experiment was repeated I could find another way to dry the potatoes
that would ensure that all were dried in the same way for the same
time. However with all this said I think that the experiment was truly
successful and I was very pleased with the complete comparison of my
results with my initial prediction.

I think my results were quite reliable. They weren't a reliable as I
would have liked. There were quite a few problems which affected my
results. The heat intensity of the sunlight and humidity of the
classroom could have affected the results. The room temperature was a
major factor in the experiment as it could have affected the rate of
osmosis. Another thing which could have affected my results was when
we were cutting, measuring and weighing the potato samples, the first
potato samples that were investigated could have changed in size by
the time all of the potato samples were investigated.

I think that my results are sufficient enough to form a conclusion
because from my investigation I have come to the conclusion that as
the concentration of the sucrose solution increases the weight and
length of the potato samples decrease. This conclusion that I have
found agrees with the osmosis theory that if a cell is bathed in a
concentrated solution, the cell would shrink in size and become
plasmotised.

There were a number of anomalous results in my investigation. This
might have occurred because:-

? The potato samples were left out to long during the investigation of
each potato sample.

? The sunlight and humidity of the classroom could have affected the
sample.

? There might have been a human error with the measuring and weighing
from a group member.

? The potato sample might have been damaged during the course of the
experiment.

I could have carried out some further work on this investigation to
extend and broaden my results. I could have investigated other
vegetables such as carrots. I could have also increased the sugar
concentration to find out when a plant cell could finally stop
decreasing in size. I could have done another investigation using the
same vegetable but this time using a salt concentrated solution. I
could compare the results. I could have investigated different plants
such as marsh plants to see if different plant cells living in
different conditions could affect the results and not agree with the
osmosis theory.

The Effect of Water and Sucrose Solution on Plant Tissue 9.2 of 10 on the basis of 752 Review.