• 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 Coursework. Investigation to determine the water potential of apple tissue and carrot tissue, and how they compare to each other.

Extracts from this document...

Introduction

Investigation to determine the water potential of apple tissue and carrot tissue, and how they compare to each other. Introduction: Water potential is the potential energy of water, relative to pure water (one without any impurities, such as ions); it's basically a numeric term that describes the tendency of water to move between two areas - due to mechanics such as osmosis or gravity. Measured in kiloPascals (kPa), the maximum measure of water potential is 0kPa (achieved by distilled water) and the water potential drops into negative numbers as the water purity decreases. As such, all solutions have a negative water potential. Osmosis doesn't require any energy - it is an example of passive transport which involves the movement of water molecules from an area of high water potential to an area of a lower water potential, across a selectively-permeable membrane. Hypothesis: Apples will have a lower water potential than carrots. I believe this because apples are fruits, and as such contain more sugars and other solutes that carrots which make them sweet, which reduces the water potential. Null Hypothesis: The water potential of apples and carrots will be the same. Variables: Independent variable: I will manipulate the concentration of the sucrose solutions (which will change the water potential). The concentrations will be 0.0mol.dm-3, 0.2mol.dm-3, 0.4mol.dm-3, 0.6mol.dm-3, 0.8mol.dm-3 and 1.0mol.dm-3. Dependant variable: I will measure the mass of the plant tissue on a balance, accurate to 2 decimal places in grams. ...read more.

Middle

Confirm with a thermometer. * While the solution's temperature stabilises in the water baths, prepare the apple and carrot samples. Use a cork borer to extract 18 pieces of tissues from the apples and the carrots. Use a knife to cut each sample to the same length (3.0cm). * Use a balance to measure the mass of all 36 samples of tissue and make sure that the masses are equal. Record the mass of each piece of tissue, including details of which samples will be used for each concentration. * Whilst disturbing the water bath as little as possible, place all samples of plant tissue into the respective test tubes and start the timer. * Once precisely 40 minutes have passed, remove the test tubes from the water baths and remove the tissues from the test tubes. Use paper towels to blot each piece of tissue to remove excess solution and measure the mass of each sample, recording the results in a table. * Calculate the percentage change in mass for each sample (change in mass/original mass*100) and plot this against the concentration of solution used on a graph. * On aforementioned graph, read off the concentration for which there was no change in mass and convert it into water potential - this is the water potential of the tissue. Results: Apple data: Raw data: masses of apple samples for concentrations of sucrose solution Concentration of sucrose solution (mol.dm-3) ...read more.

Conclusion

samples; which is when water started to pass out of the samples and into the sucrose solution, causing a decrease in mass. The other part of my hypothesis, where I stated that the apples would have a lower water potential than carrots, appears to be supported. Since apples contain a greater number of solutes than the carrots (according to http://wiki.answers.com "all fruits contain natural sugars, especially fructose"), which lowers the water potential. Evaluation: This investigation could have been improved: * Making sure that the tissue samples are identical is nearly impossible - size, mass and surface area all affect the rate of osmosis and I only concentrated on achieving similar mass and sized samples. A machine to slice/dice the tissue into chips of the same sizes would remove the human error component of preparing the samples. * Weighing each sample after immersion allowed for different amounts of solution to remain on the samples - I patted each sample with a paper towel, but it's possible that in doing so, some water was squeezed out of the samples or that excess solution was still present on the samples. Being extremely careful with this step is very time consuming, but it would have produced slightly more valid results. * The plant tissues used should be fresh, since older tissues will lose moisture quickly, or possibly even rot - affecting the results. * The particular brand or carrots/apples used in the investigation are only representative of those brands, and not carrots/apples in general. ...read more.

The above preview is unformatted text

This student written piece of work is one of many that can be found in our AS and A Level Molecules & 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 AS and A Level Molecules & Cells essays

1. ## Biology Coursework Investigation

3 star(s)

- The temperature of enzyme (input variable) - This is another input variable which if changed will alter your overall results. This is due to the fact that enzyme activity increases as temperature increases, until an optimum temperature is reached; then the activity rapidly decreases until the enzyme no longer works.

2. ## DETERMINING THE WATER POTENTIAL OF A POTATO TUBER CELLS USING THE WEIGHING METHOD.

All the potatoes need to be the same length, and so an average ruler is the easiest thing to use to measure the potato chip lengths 15cm * Make sure the edges are not blunt or crooked 14. White tiles 1 To cut and core the potato on.

1. ## Affect of sucrose concentration on the rate of respiration.

Conical flask (250cm3) Beaker (500 cm3 ) Beaker (1dm3 ) Boiling tube 2 thermometers Measuring cylinder (100cm3) Syringe(5 cm3) Glass rod Spatula Clamp Stand Collecting bath(plastic container) Capillary tube (connecting) Stop watch Reason for chosen apparatus Within my chosen apparatus I have chosen a 250cm3 conical flask, the reason why

2. ## An experiment investigating the concentration of sucrose in cells of carrot and potato

From my preliminary I learnt to place a piece of tissue paper on the scales to soak up excess water so that it does not interfere with the mass measurement. I do feel however that measuring the length of the potato chips is not a precise enough measurement because it

1. ## Experiment to investigate the water potential of potato tissues when immersed in various sucrose ...

When water molecules enter the plant tissue in osmosis, the portion of the cell known as the protoplast (which is the cell surface membrane, tonoplast and cytoplasm) exerts a pressure against the cell wall, which, due to its limited extension, will resist the entry of further water molecules.

2. ## An Experiment to Determine the Water Potential of a Plant Tissue

The cell has been plasmolysed. Using this concept we can deduce that the point on the graph where the curve of best fit crosses the x-axis, the x intercept, is the point at which the sucrose solution is the same as the solution in the beetroot cells, the solution is isotonic.

1. ## A Level Biology revision notes

are produced more rapidly and in larger amounts T-Lymphocytes: Cell-Mediated Response * Pathogens that quickly enter cells are more difficult to remove (viruses, tuberculosis) * Infected cell is directly destroyed / no antibodies involved * This is done by binding to the self and non-self antigen o Prevents destruction of

2. ## Catalyse Investigation

Although only slowly, hydrogen peroxide still decays in the absence of a catalyst (even in a fridge). This could affect the results. 2. 2. Set the apparatus up in the way shown above, making sure that no (or as little as possible)

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