• Join over 1.2 million students every month
  • Accelerate your learning by 29%
  • Unlimited access from just £6.99 per month

Potato Cores in Salt Solution.

Extracts from this document...

Introduction

Potato Cores in Salt Solution Aim The aim of this experiment is to investigate the movement of water into and out of plant cells by osmosis. The cells chosen for study will be taken from potato tubers as they provide a ready supply of uniform material. Background Information Any substance dissolved in water is called a solute; a solvent is a liquid that is able to dissolve another substance, called a solute, to form a solution. The water content of plants varies depending on environmental conditions. In land plants it plays a vital role in structural support and mineral transport and thus a lack of water may lead to wilting or possibly death. Water is mainly absorbed through the roots, which are covered in specially adapted root hair cells, with large surface areas and thin cell walls to aid absorption by osmosis. The evaporation of water through stomata on plant leaves causes a transpiration stream, causing the water to be drawn up through xylem vessels. Osmosis is the flow of water molecules by diffusion through a partially permeable membrane from areas of high water potential (low solute concentrations) to regions of low water potential (high solute concentrations). All plant cell membranes are partially permeable, which means they allow some some substances to penetrate them but not others. Whether water enters the cell by osmosis will depend on the balance between external and internal solute and water potentials. ...read more.

Middle

� Place all boiling tubes into boiling tube rack. � Place 20cm3 of each solution into each of three separate boiling tubes. This will result in eight sets of three test tubes, with each of the eight sets containing different molar concentrations of sodium chloride ranging from 0.05molar to 0.40 molar. � Place 20cm3 of pure distilled water into each of three separate boiling tubes. � Cut 27 potato cores from the same large potato and place them onto a ceramic tile. � Using a scalpel and ruler (calibrated in millimetres) cut the cores into 50mm lengths, with care taken to ensure no potato peel being left on them. The cutting will be to an accuracy of 1 millimetre. � The cores will then be individually weighed on a top pan balance to an accuracy of 0.01 grams. � Each of the cores will then be placed, into one of the 27 boiling tubes for a duration of 2 hours. � The timing will be done using a stopwatch. � After 2 hours the cores will be removed and weighed directly on the top pan again to measure changes in mass. � Directly after weighing the cores, they will be measured again on a ceramic tile using a ruler in order to note any changes in length. � After the experiment has been completed all the apparatus will be properly placed away and all the potato cores will be disposed of. ...read more.

Conclusion

If the cells have become fully plasmolysed then the plant cells are unable to cope with the low external water potential. If the cells have not become fully plasmolysed then recovery could be possible and the effects of osmosis have not been life-threatening for the plant in the short term. Improvements It would have been beneficial to have repeated the experiment more times to make certain that the results were not gained through chance or by an external factor. A greater range of molarities over smaller increments would have shown more accurately any changes in length and masses of potato cores. Ideally all samples should have come from the same part of the potato, as this would have decreased the chances of variations in texture. The size of the potato cores were more than likely to be inconsistent in shape as they were cut by hand using a ruler for measurement. It may have been more appropriate to use a template of some sort. A variety of other similar plant roots could have also been placed through the same procedure in order for comparison. The experiment was also limited by the accuracy of the top pan balance, which was to one decimal place, and the calibration of the ruler. It was also unlikely that room temperature and pressure remained consistent throughout the experiment conduction, and changes in temperature may have altered the rate of diffusion. The potato cores should have had any excess water on their outer surfaces removed by blotting with blotting paper before being re-measured, as this is likely to have altered the masses of the cores. ...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

See related essaysSee related essays

Related GCSE Life Processes & Cells essays

  1. Marked by a teacher

    To determine the water potential of a potato tuber cell using varying salt solution.

    5 star(s)

    and -1450?. Preliminary From the preliminary these are the changes that have been made to insure an even more reliable and accurate experiment: * In the preliminary the potato pieces were not cut in accurately sized pieces. For this experiment I will cut them accurately using a knife and ruler.

  2. Lab Research Paper. Just a Pinch of Salt and a Dash of Bacteria: the ...

    When the LB Agar was fully melted with no clumps, it was left to cool for about one or two minutes. After the LB Agar was cool enough to touch, the lip of the bottle was flame sterilized with a flame stick, and the agar was poured into the Petri plates.

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

    I then had 15 chips. 3.Taking a test tube rack I placed 5 test tubes and then labelled them 0 molar, 0.25 molar, 0.5 molar, 0.75 molar and 1 molar. 4. Using a pipette I put the same amount of each different concentration of solution and put each test tube

  2. INVESTIGATING OSMOSIS AND WATER POTENTIAL IN POTATO CORES

    As the solute potential of the solution containing the potato tube is increased then the increase in mass will also decrease until a point is reached when the water potential inside and outside is the same and no change in mass will be recorded.

  1. Osmotic pressure

    Water molecules move randomly, and when water is enclosed by a membrane, living or artificial, some of the moving water molecules will hit the membrane, exerting pressure on it. This pressure is known as water potential. As the number of water molecules increases, the number of collisions between the molecules

  2. Investigating the effect of different concentration of glucose (C H O ) and salt ...

    The greater the pressure inside the cell, the greater the tendency will be for water to leave it. Water potential (?) = solute potential (? ) + pressure potential (? ) Solutions can be isotonic, hypotonic or hypertonic. They are terms that describe how the solute potentials of solutions compare with each other.

  1. Invetigation on osmosis in potato cores.

    the cells will lose water by osmosis. Again, water crosses the cell membrane in both directions, but this time more water leaves the cells than enter it. Therefore the cell will shrink and the potato core loses mass. The Consequences of Osmosis in a Plant Cell Plant cells always have a strong cell wall surrounding them.

  2. Determination of molarity of cell sap in potato tubers.

    So they will be in balance and proportion. In plants the following occurs so that the plants may take in fresh water and if seawater were added the reverse would happen, the cells would lose water. This we will see later.

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