• 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

How does the concentration of salt solution affect osmosis in potatoes?

Extracts from this document...

Introduction

Year 10 coursework - Osmosis How does the concentration of salt solution affect osmosis in potatoes? Introduction Osmosis is movement of water through a selectively permeable membrane, from where there is a higher water concentration (or water potential) to where the water concentration is lower. In this piece of coursework I will answer the question, 'How does the concentration of salt solution affect osmosis in potatoes?'. If you put a piece of potato into pure water, the water concentration is obviously higher outside the potato. Therefore water moves into the potato by osmosis. This will cause the potato piece to swell. However, if you put a piece of potato into a strong salt solution (where the water concentration is low), then water will move out of the potato. The potato piece will therefore shrink. If a salt solution has exactly the same water concentration as the potato piece, then it is likely that there will be no overall movement of water in or out of the potato. ...read more.

Middle

If you put a plant cell in water, water enters by Osmosis, then swells up. However, the cell will not burst. This is due to the fact that the cell walls are made from cellulose, which is extremely strong. Eventually, the cell stops swelling, and when this point is reached, we say the cell is turgid. This is important, because it makes plant stems strong and upright. The experiment I will do is to find the water potential of a potato, by putting potato pieces into different solutions of salt of known concentrations, until I find the concentration where the potato piece stays the same size. To make this experiment a fair test, I would need to keep everything else constant as far as possible. For example, I need potato pieces of the same size, and should always use the same volumes of salt solutions. Prediction I predict, that as concentration increases, the weight and length of the potato chip will decrease. ...read more.

Conclusion

Relating this to the potato chips: basically, as the concentration of salt in each solution increases, the water in that solution is less able to move to the potato, causing water from the potato to move to the solution, decreasing its length, weight and width. Osmosis is established when a semi-permeable membrane is placed beween two solutions. In biological systems osmosis is the exchange of water between the toplasm and the surrounding medium, with the plasm membrane being the semi- permeable membrane. An example of this in my results is the test at 1 molar. In other words, it becomes dehydrated and loses water through plasmolysis. If the concentration of the salt solution (in our case Glucose solution) outside the cell is less than that inside the cell, this means that the solution is Hypotonic to the cells of the potato chip. The water will diffuse into the cells, making it turgid. This would explain why potato chips put into a solution of 0 molar seemed very firm compared to the potato chip used for 1 molar, this was because the cells of the potato had lost their turgor, and had become flaccid. ...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

Here's what a teacher thought of this essay

4 star(s)

****
A very clear account showing a detailed understanding of osmosis written using a good standard of GCSE level biological terminology. Better coverage of variables needed for 5 stars.

Marked by teacher Adam Roberts 10/05/2013

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. Biology Coursework - Osmosis

5 star(s)

The variable I have selected as my independent variable is the concentration of sucrose solution that the potato chips will be placed in. The dependant variables I have chosen to measure are: the mass of potato chip after osmosis and the volume of solution remaining after osmosis.

2. Osmosis in Potato Chips

5 star(s)

The water molecules will be travelling down the concentration gradient, like this: I will be able to tell if this has happened by the weight of the potato chip. If it weighs less than before it must have lost water.

1. Isotonic Point of Potatoes

5 star(s)

measuring cylinder Even though the volume does not influence the concentration, the volume should be kept constant in order to maintain a fair test. Time for which potato chips are kept in each solution All the trials will be kept for 24 hours If the potato chips are left for

2. Potato / Osmosis Experiment.

5 star(s)

The concentrated solution always remained the same and was obtained using a pipette. 4. Place each sample in its own solution in their own test tube. 5. Take out samples from their solution, reweigh them and record. This was done 2-2 and half hours after setting up the test tubes.

1. Aim To determine the water potential of a potato tuber cell

The evidence/results I obtained while doing my experiment matches the prediction I made quite well. This is because it is clear by looking at my table of average results and my line graph that the average change in mass, in the potato cylinders, decreased in lower concentrations of water and increased in higher concentrations of water.

2. Experiment investigating concentration of sucrose solution and potatoes

This will hopefully produce more accurate results from which I will be able to draw a more accurate conclusion. Concentration of sucrose solution(molar) Amount of sucrose solution (cm3) Amount of water (cm3) 1.0M 10 change measurments 0 0.8M 8 2 0.6M 6 4 0.4M 4 6 0.2M 2 8 Method for preliminary experiment : 1.

1. The Effect of Solute Concentration Upon the Rate of Osmosis

This same process will occur after another 10 minutes in their solution, and again after 10 more minutes. After this has been done, I will have a full set of collected results for the potato cubes in the 0.0M, 0.2M and the 0.4M solutions.

2. To find out the internal concentration of a potato cell.

Each piece of visking tubing was submerged in a different external sugar solution of 0.0M (distilled water), 0.2M, 0.4M, 0.6M, 0.8M and 1.0M. After 30 minutes they were removed, dried and the mass was re-recorded. The percentage change in mass was calculated to obtain a true comparison of change in mass, since the visking tubing bags started at different masses.

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