Osmosis. Aim: To study the effect of distilled water and different concentrations of sucrose solutions on the length of potato strips and thereby investigate the water potential of the potato cells in the aforementioned liquids.

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Osmosis

Aim: To study the effect of distilled water and different concentrations of sucrose solutions on the length of potato strips and thereby investigate the water potential of the potato cells in the aforementioned liquids.

Introduction: Osmosis is the diffusion of water through a semi-permeable membrane from an area of high water potential (low solute concentration) to an area of low water potential (high solute concentration). It is a passive process in which energy is not required.

Materials:

  • 6 large test tubes
  • Cork bore (5 mm)
  • Scalpel
  • Potatoes
  • Distilled water
  • Sucrose solutions (0.2, 0.4, 0.6, 0.8 and 1.0 mol/dm-3)

Method:

  1. With the help of a knife slices of about 0.5 cm think were cut from a potato (as uniform as possible). Using a ruler and a scalpel, 18 strips of potato were cut from these slices. These strips were about 0.5 cm wide and exactly 4 cm long.
  2. Three strips were placed in each of the six test tubes.
  3. Enough distilled water was added to one of the test tubes to cover the potato strips.
  4. Sucrose solution of five different concentrations was added to the remaining five test tubes so that it covered the strips and the test tubes were labeled accordingly.
  5. The potato strips were allowed to be suspended in their corresponding solutions for 30 minutes.
  6. The liquid was then drained off from each of the test tubes and the length of each strip of potato was measured as accurately as possible.
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Results:

Table 1: Length of potato strips after 30 minutes of suspension in distilled water and different concentrations of sucrose solution (data shown from all four groups)

The data marked in bold is the data collected in our group

Calculating the mean and standard deviation using; where,  is the length of potato strip; is the mean length of the potato strips and is the number of observations.

Table 2: The mean length of the potato strips in various solutions and the standard deviation from the mean.

Fig 1: Figure depicting change in mean ...

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