• Join over 1.2 million students every month
• Accelerate your learning by 29%
• Unlimited access from just £6.99 per month
Page
1. 1
1
2. 2
2
3. 3
3
4. 4
4
5. 5
5
6. 6
6
7. 7
7
8. 8
8
9. 9
9

# Osmosis experiment

Extracts from this document...

Introduction

Osmosis experiment Osmosis is the passage of water molecules, which have moved from a high concentration to where there is a low concentration through a semi - permeable membrane. Aim: We have been asked to investigate the effect of osmosis on potato chips, and therefore the effect of osmosis in plant cells. My main aim is to determine whether osmosis occurs in a potato and how it affects the potato in different molar solutions of sucrose and distilled water. I shall be experimenting with a baking potato, and will be using a range of different concentrations of sucrose, and distilled water. By measuring the change in mass and length of the potato cylinders I should also be able to find the isotonic point. An isotonic point is a point where the mass does not increase or decrease from its original mass. I must also experiment with at least 5 types of concentrations, to have sufficient results ,and to see if my prediction is correct I am going to use 6. The diffusion theory of Osmosis: (from 'GCSE BIOLOGY' by D.G. Mackean.Page 36.) Partially permeable sugar molecules pass Membrane through pores more slowly Fewer water molecules more water molecules go in this direction going in this direction Hydrated sugar molecule. Variables: We could: * Look at the type of temperature. * Compare a potato with a parsnip for example. * See if the potato changes with different solutions * I have actually chosen to investigate different molar concentrations of sucrose - by measuring the mass and length of the cylinders. Fair test: To create a fair test certain aspects of the experiment have to be kept the same whilst one key variable is changed. I have chosen to vary the concentration of the sugar solution. This will give me a varied set of results from which I hope to make a decent conclusion. If any of the non-variables are not kept constant it would mean that the test was not fair. ...read more.

Middle

(No.2.7 from a worksheet about plant cells) Cell surface membrane Concentrated solution Less concentrated solution Water diffuses out of the first the cell shrinks slightly, and Cytoplasm and vacuole becomes flaccid; then the cell t through a partially membrane pulls away from the Ppermeable cell membrane cell wall, and the cell is plasmolysed. Osmosis takes place Appearance: Over 24 hours I think the colour of the potato chip will get lighter and fade in the distilled water and possibly 0.1M solution. E.g. if the potato chip was at first a golden yellow colour I think that after 24 hours it would change to a pale white colour. This is because the cell in the potato has become turgid, and water has entered the cell by osmosis. I also predict the chips in 0.2M - 0.5M solution should be dark in colour, and bendy and brittle in texture. This is because the cell has become flaccid. The cell will become flaccid when plasmolysis has occurred. The cell will become flaccid when plasmolysis has occurred. Plasmolysis is when the cell membrane peels away from the cell wall. A flaccid cell is the complete opposite of a turgid cell. Results: This is a table to show the change in mass in the potato chips. Solution used Original Mass (g) Final mass (g) Change in mass (g) Average change (g) % change in mass Average % change 1.73 1.9 0.17 9.83 Distilled water 1.66 1.82 0.06 0.1 3.16 15.3 1.6 1.69 0.09 5.63 1.67 1.76 0.09 5.39 0.1M sucrose 1.68 1.74 0.06 0.06 3.57 8.19 1.77 1.82 0.05 2.82 1.65 1.7 0.05 3.03 0.2M sucrose 1.69 1.75 0.06 0.04 3.55 7.13 1.83 1.83 0.03 1.64 1.8 1.71 -0.09 -5 0.3M sucrose 1.82 1.67 -0.32 -0.19 -16.6 -25 1.66 1.49 -0.17 -10.2 1.76 1.49 -0.27 -15.3 0.4M sucrose 1.74 1.51 -0.23 -0.29 -13.2 -41.5 1.79 1.44 -0.39 -21.8 1.86 1.5 -0.36 -19.4 0.5M sucrose 1.92 1.52 -0.4 -0.37 -20.8 -46.8 1.85 1.46 -0.36 -19.5 % change in mass = change 100 anomalous result. ...read more.

Conclusion

E.g. 0.000g not 0.00g. I was also very surprised as I only had two small anomalous results which means my results were probably fairly reliable. To observe these results look at my graphs or results table. An anomalous result is a result which does not follow the pattern of the other results and so is abnormal or irregular. If I was to carry out this investigation again I could use different varieties of potato or different plant tissues e.g. carrot instead of potato. This way I would be able to compare the results and see what differences and similarities were between the two types of plant tissue. The range of concentrations was adequate but I would possibly create more concentrations if I repeated the experiment so that I would have more varied results, i.e. 0.10M, 0.50M, 1.0M, and so on. This way would have allowed me to also find out the isotonic point far more accurately as the one that I estimated is very approximate. Three repetitions of each concentration are sufficient but unfortunately there were anomalous results (circled on graph). This part of the investigation may need to be repeated, as it did not seem accurate. I think I took just enough results but if I were to do this investigation again I would certainly take more so that I would have a greater chance of obtaining more reliable ones. There were no out of the ordinary results, but some were not as close to the lines as others. This may have been caused by human. When the potato chips were removed from the flat bottomed tubes and dried i may well have dried some more thoroughly than others and so some would have more excess water, which would add mass. If the experiment was repeated I could find another way to dry the potatoes which would ensure that all were dried in the same way for the same amount of time. Although I could not draw a firm conclusion I could see a trend and I was very satisfied with the complete comparison of my results with my initial prediction. ...read more.

The above preview is unformatted text

This student written piece of work is one of many that can be found in our GCSE Life Processes & Cells section.

## Found what you're looking for?

• Start learning 29% faster today
• 150,000+ documents available
• Just £6.99 a month

Not the one? Search for your essay title...
• Join over 1.2 million students every month
• Accelerate your learning by 29%
• Unlimited access from just £6.99 per month

# Related GCSE Life Processes & Cells essays

1. ## Investigating the effect of Sucrose Concentration on the Rate of Osmosis in Potato Chips.

5 star(s)

to float in solutions of strong sucrose concentration because the potato was less dense in the sucrose concentration. This did not happen in the water because the potato chip was denser than the pure distilled water. Therefore I have reduced the size of the chips so that they are the same lengths as the cups' diameters (5cm)

2. ## To investigate how varying the concentration of sucrose solutions affects the rate of osmosis ...

3 star(s)

They would have shrunk, resulting in a decrease of length and mass when immersed in the solutions. As expected, they increased in mass and length when immersed in distilled water. Comparing the results I obtained for each solution, I was surprised to find the potato cylinders immersed in 0.125M solution also gained mass and length.

1. ## Find the rate of osmosis in different vegetables (Carrot, Potato, Swede, Parsnip and Sweet ...

3 star(s)

I researched the sugar content of my selected vegetables using the Internet, and I found that: * Parsnip-9mg/100g * Potato- 7.7mg/100g * Swede-7.2mg/100g * Sweet Potato-7.7mg/100mg * Carrot- 6.8mg/100g When I have the results, these figures should allow me to prove and support my conclusions, or show the lack of accuracy and fault in my experiment.

2. ## 'Investigating how isotonic, hypertonic and hypotonic solutions affects the total mass of a potato ...

Water molecules are free to pass across the cell membrane in both directions, but more water will come into the cell than will leave. The net (overall) result is that water enters the cell. The cell is likely to sell up.

1. ## Osmosis. Aim ...

The change at salt concentration 100% slowed down but still was decreasing to a percentage of -14.52% of average. Conclusion At 20% concentration of salt solution the concentration of water in that solution is much higher than the water concentration in the cells of the potato.

2. ## Aim: To find out the effect of altering the concentration of sugar solution on ...

After this, I will weigh each potato chip on a scale so that each is not just of a similar size but also of similar mass. I will then add a potato chip to 10ml of the appropriate sugar concentration solution in the test tube.

1. ## Osmosis is defined as 'the movement of water molecules from an area of high ...

number of results are used, or a difference in the potato for those cylinders. Either of these would easily be recognised if a larger number of results were collected and used. Another result that appeared unusual was the ��step�� in the graph for the sucrose solution between 0.25% and 1%

2. ## Use scientific knowledge and practical skills to determine the effect of a range of ...

is low. This could be called a weak or dilute solution. In a low concentration of water the amount of solute (e.g. sucrose) is high. This could be called a strong or concentrated solution. When two such solutions are divided by a semi-permeable membrane the water will move from

• Over 160,000 pieces
of student written work
• Annotated by
experienced teachers
• Ideas and feedback to