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

Experiment to investigate the water potential of potato tissues when immersed in various sucrose solutions of different concentrations

Extracts from this document...


Experiment to investigate the water potential of potato tissues when immersed in various sucrose solutions of different concentrations Aim: The aim of this experiment is to determine the water potential of potato tissues when immersed in different concentrations of sucrose solution and find the point at which the cells in the tissue are incipiently plamolysed. The immersion of the tissue in different concentrated solutions will enable an understanding to be developed of which concentrations the water potential is greater in the cell in comparison to the external solution; lower in the cell than in the external solution and ultimately, equal in both solutions thereby identifying the normal sucrose solution of the cells and the point at which the cells within the potato tissue are incipiently plasmolysed. Background Theory: Incipient plasmolysis is the point at which the water potential within a cell and the water potential of its external solution are equal. In order to understand this, the concept of water potential must first be grasped. Water potential, represented by the Greek notation psi (?), is the tendency of water molecules to move from one place to another as a result of the pressure created by these molecules. Water molecules will always move down a water potential gradient, which is from a region of higher water potential to a region of lower water potential. Equilibrium is reached when the water potential of both regions are equal and there is no longer any net movement of water molecules. This net movement of water molecules between two different systems with varying water potentials across a partially permeable membrane is the process of osmosis. Water potential is affected by two factors: solute potential (?s) and pressure potential (?p). Solute potential is the amount by which the presence of solute molecules lowers the water potential. The greater the amount of solute molecules present (and thus the more concentrated the solution), the greater the amount by which the water potential is lowered. ...read more.


Firstly, the range of concentrations used by Marilyn (a number of concentrations close to the predicted point at which incipient plasmolysis was likely to have occurred) allowed the results obtained to be of an accurate nature. The results were also likely to have been valid due to Marilyn's expertise and skills in the area due to her professional background. Furthermore, it is likely to have be regarded as appropriate to use Marilyn's results as a basis for the prediction due to be made as her experiment was also central to the water potential of potato tissue specifically. Dissimilar to the investigation carried out by the students at the US School, Marilyn aimed to investigate the water potential of potato tissue through the means of measuring the change in length of the tissue after immersion, rather than measuring the change in mass. Although using length is likely to be less accurate (especially due to the fact that the electronic balance used to measure mass is far more precise (0.001 g accurate) than the vernier calliper (0.1mm accurate) used to measure length), it is likely to be a more reliable means of measuring the water potential as there is less room for error. As a result, this method shall be adopted as a means for investigating the water potential for the experiment due to be undertaken. Marilyn did not however use the same initial length for each of the potato tissues before immersion in to the sucrose solutions. Although this did not have any effect o the validity of the results, it would have been easier to have the same initial length when comparing different readings. The preliminary study and the secondary data have enabled an understanding to be developed of the best possible means of carrying out the proposed experiment. The following summarises the methods that shell be adopted as a result of these previous studies: * The experiment shall aim to investigate the water potential of potato tissue and thus the point of incipient ...read more.


A further variable which must be kept constant is the temperature in which the sample tubes are kept. This is because temperature can have an effect on the level of osmosis that occurs. Risk Assessment: When carrying out an experiment of this nature, it is important to acknowledge the need for safe working. There are many aspects within the investigation that are hazardous and could thus, cause possible harm to those carrying out the experiment. Focal to the experiment is the use and production of various solutions. There is therefore a likelihood of spillages occurring. Such spillages could be hazardous as they could cause falls and other such accidents. In order to prevent such incidents from occurring, those involved in carrying out the experiment must therefore ensure that any spillages are cleaned up immediately. It may also be appropriate to warn others if a spillage occurs so that they are aware of the potential risk. Furthermore, another potential hazard lies in the great use of glass ware within this experiment. A number of apparatus required in order to carry out this investigation appears to be made of glass and therefore of a delicate nature, such equipment include pipettes and the sample tubes. It is thus possible that breakages may take place. Breakages are likely to cause great harm if caution is not taken. Such measures that are required to be enforced if breakages were to occur include using a dustpan to clear all fragments of broken glass and disposing of such material through an appropriate means and also, alerting those in the surrounding area. The final potential hazard existent in the carrying out of the proposed experiment is the use of sharp objects such as the scalpel and cork borer when cutting the potato cylinders. Recklessness when handling such objects is more than likely to result in accidents and bodily harm. In order to avoid such events, those carrying out the experiment must ensure that they take great care and handle the objects by the correct means, i.e. cutting the potato cylinders away from themselves correctly on the cutting tile. ...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

See related essaysSee related essays

Related AS and A Level Molecules & Cells essays

  1. Marked by a teacher

    Aim: To estimate the solute potential of a plant tissue.

    investigation are that part of the procedure that was changed was the time. Instead of the epidermal cells being left in the solutions 20 minutes, they were left for a day. Not only, were they left much longer, but the molarity of the solutions could have also changed since they


    Water absorption causes the symplast to push against the cell wall so as to create a positive hydrostatic pressure, or turgor pressure that is necessary for cell growth and the support of young, non-lignified tissues. Water potential is always measured as a negative number; this is because the water potential

  1. An experiment to find of the isotonic point of root vegetables cells in contents ...

    As a greater net movement of water will occur out of the diluted sugar solution the cell will become flaccid. This can be directly linked to my investigation, if I place a root vegetable cylinder into a solution with a higher solute concentration, the outer layer of my root vegetable

  2. To find out how different concentrations of sucrose solution affect the incipient plasmolysis of ...

    higher solute potential and a lower water potential therefore net movement of water molecules will be out of the cell and into the hypertonic solution because there is a higher water potential in the cell then there is in the hypertonic solution causing the cytoplasm to shrink and the membrane

  1. Free essay

    An experiment measuring the potential difference generated by various simple electrochemical cell

    (See diagram). Make sure the 2 electrodes are connected to the correct terminal of the voltmeter - the more reactive/ better reducing agent at the negative terminal (on the left) and the less reactive/ better oxidising agent at the positive terminal (on the right).

  2. Affect of sucrose concentration on the rate of respiration.

    ------ Method 1. Below is a detailed list of the procedures that I am going to carry out in order to obtain reliable and accurate results. 2. To begin the experiment, firstly wash and clean all the equipment. 3. As the yeast has to be activated for 15minutes, this should be done first.

  1. An Experiment to investigate the factors that affect the Power Output of a solar ...

    which effectively means that there are fewer electrons, so it carries a positive charge. Initially the silicon is neutral. However, when the N-type and the P-type silicon meet, they lose their neutrality. This is because the N-type silicon has loose electrons finding holes, and the P-type silicon has the holes that the electrons are looking for.

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

    A cell is in this state when the sucrose concentration outside the cell is equal to the sucrose concentration inside the cell and therefore there is no net movement of water. It is at equilibrium status. On a graph of percentage difference against sucrose concentration, the point of incipient plasmolysis

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