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Transcript

Effect of Salinity on Potatoes

The Experiment

Introduction

Procedure

Each group was assigned a salt concentration to test: 0%,.9%,5%,10%, and 15%.

Our group was 5% salinity.

Steps

The objective of this experiment was to measure the effect of osmosis on potato cylinders to represent how plant cells absorb water through osmosis. Osmosis, a type of diffusion, plays a vital role in stability and growth in plants. Cells have selectively permeable membranes that only allow the movement of specific solutes.Osmosis is the movement of water molecules through a selectively permeable membrane from higher water concentration to a lower water concentration - or - down a concentration gradient.

1. Using the cork borer, press into the potato to make potato cylinders. Cut off any skin.

2. Cut the potato cylinders so there is 3 cylinders that are 20 cm in length.

3. Put the three cylinders in the weigh boat and place the boat on the scale to obtain an initial mass, in grams. Record mass.

4. Place cylinders into the salt solution and wait 30 minutes.

5. After 30 minutes, take out the cylinders and bloat dry the excess water.

6. Weigh the potato cylinders, measure the potato cylinders

7. Leave potato cylinders in solution over night.

8. After 24 hours, measure and weigh the potato cylinders.

What were our group's results?

What do these results mean?

Water is moving out of the potato at 5% concentration. However at 0%, there is dynamic equilibrium. An equal amount of water is moving in and out of the cells.

The water in our potato cylinders moved from the cells of the potato into the solution because it had an area of lesser water potential.

Other Groups' Results

Why is this important?

Crop Yields

"Salinity stress is a critical environmental constraint to crop productivity especially in arid and semiarid

regions. The most of the crop plants is intolerable to high salinity conditions resulting decreased yield.

Generally, plants are stressed in three ways in saline soils a) low water potential of the root medium leads

water deficit, b) the toxic effects of the Na+ and Cl -

and C) nutrient imbalance by depression in uptake and/or

shoot transport (Munns and Termaat 1986, Chapin 1991, Marschner 1995). "

Importance as Food

  • 4th biggest crop in world
  • Average American eats more than 140 pounds a year

Sources of Error

Preciseness of Solutions

If the salt solutions had too much or too little solute, it could have changed the reaction of the potato cells. A more salty solution is, the more likely the water will move out of the potato. If the solutions were wrong, our data could be wrong.

Initial Weight/Length

If the initial weight or length of the potato was incorrectly measured, the amount of change is wrong, and therefore the calculations of the effect of salinity can be changed.

Temperature Control

We did not monitor temperature.

Temperature can effect reactions and rates of reactions and processes.

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