Investigation to compare the water potential between potato chips and carrot chips.

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Balwant Flora 12SU                                                                                       05/05/2007

Investigation to compare the water potential between potato chips and carrot chips

Investigation to compare the water potential between potato chips and carrot chips

Introduction

For this investigation I will be investigating and comparing the water potential between carrot chips and potato chips. This Preliminary work which I did before this (Investigation to determine the effects on potato chips in different concentration of sucrose solution) will help me complete this with the minimal errors possible.

        I will develop my ideas further from what I did from the preliminary work and adapt it to help me complete this investigation.

Aim

The aim of this investigation is to carry out a suitable experiment, using preliminary work, to compare the water potential of potato chips and carrot chips as fair as possible.

Background Information

I already know that:

The main thing is that osmosis takes place and because of this water moves down a water potential gradient.

Water moves out of a cell if the water potential is lower outside the cell and if there is a high solute potential outside of the cell as shown in the diagram below:

 

I also know that water moves from a high concentrated area of water molecules to a low concentrated area of water molecules until equilibrium is reached. When plant cells become full of water they become turgid and the cell wall is a means of stopping the cell from bursting. Also, plant cells with very little water becomes flacid, this may be because water moved from a high concentrated area (plant cells) into a low concentrated are (area surrounding plant).

I know this information without researching but when I looked through the Biology 1, OCR, Cambridge book (pages 56, 57 and 58), I found out that:

Water with solutes in has a water potential below zero (in the minus figures). A way to work out water potential is to use the formula:

Water potential = solute potential + pressure potential.

Plasmolysis takes place in plant cells and it is the process when the water potential is equal to the solute potential. Incipient plasmolysis is the point just before a plant cell is about to plasmolyse and the pressure potential has just reached zero.

I also found the following information from     :

The four factors that effect water potential are:

  1. Concentration – water moves from a dilute solution to a concentrated solution.
  2. Pressure – water goes from high pressure to low pressure.
  3. Gravitational pull – water is pulled down by gravity.
  4. Charge – there isn’t any charge water so it can be ignored.

I also found out the molar volume of water which is 18 x 10-6 m3 mol-1.

If there are two solutions of different concentration which are separated by a semi-permeable membrane which is permeable to the smaller solvent molecules but not to the larger solute molecules, then the solvent will often  across the membrane from the less concentrated area to the more concentrated area. This process is called osmosis.

The transport of water and other molecules across biological  is essential to many processes in living organisms. The energy which drives the process is usually discussed in terms of .

I found this information from:                                                          

Preliminary Work

Before carrying out my actual investigation I did some preliminary work with just potato chips. I did this as it would aid me in doing this investigation with less errors and more accuracy. The idea is that as the concentration of sucrose increased the less water there would be in the potato chip because of the water potential gradient. Water would move out of the potato chip as there is a high concentration of solutes outside the potato chip and a low and concentration of water molecules. Water moves out the potato chip as it tries to reach equilibrium (same amount of water inside the potato chip and outside the potato chip). The opposite would happen in the lower concentrated sucrose solutions. Water would move into the plant as there is a higher concentration of water molecules outside the potato chip so water would move in to try and reach equilibrium. This means as the concentration increased the weight of the potato chip would decrease and as the concentration of sucrose decreased the weight of the potato chip would increase from its normal weight. This was the basic prediction that was deducted.

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I required the following apparatus to carry out my preliminary work: 1.00M sucrose, 2 Beakers – to hold sucrose solutions and water, Water, Cork borer (4mm) – cuts out accurate potato chips, Blade of some sort to cut potato chip to size, Ruler to measure length of potato chips – to get the same length potato chips, Scales – weigh the potato chips to 2.d.p for accuracy, Potato, Cutting tile, Syringe to get more accurate measurements and Measuring Cylinders to measure how much water and sucrose I need. Using this apparatus will help me seeing which piece of apparatus is ...

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