Investigation:  The Effect of Salt on a Carrot

carrot Background:

Osmosis is the movement of solvent molecules, usually water, across a semipermeable membrane from an area of lower solute concentration to an area of higher solute concentration.

Carrots, like many other plant cells, consist of semi-permeable membranes that allow water to pass through. When a carrot is placed in a solution, such as water, osmosis occurs.

If a carrot is placed in a hypotonic solution (a solution with a lower concentration of solutes compared to the carrot cells), water will move from the solution into the carrot cells. This influx of water causes the carrot cells to swell and become turgid, which can make the carrot firm and crisp.

If the carrot is placed in a hypertonic solution (a solution with a higher concentration of solutes compared to the carrot cells), water will move out of the carrot cells into the surrounding solution. This results in the cells shrinking and the carrot becoming limp and wilted.

Experiment

1.  Consider what you know about osmosis and transport across the membrane and PREDICT what will happen to carrot soaked in salt water.  

2. If you are going to place carrots in salt water, what do you need to set up as your CONTROL?  

Procedure and Data Collection: 

checkbox Use a scale to weigh your (baby) carrots in grams.  (Digital Scale)

Mass of Carrot 1 (salt) ___________         Mass of Carrot 2 (DI) _________

checkbox Place carrot 1 in a cup filled halfway with tap water, then add a teaspoon of salt. 

checkbox Place carrot 2 in a cup filled halfway with distilled water. 

checkbox Label the cups as SALT or DI water and write your initials.  Let sit overnight.

checkbox Weigh each of the carrots the next day. 

          Mass of Carrot  1 (salt) ___________         Mass of Carrot 2 (DI) _________

Analysis

3.  Describe what happened to the mass of each carrot  (did it go up, down, or stay the same).  Write in complete sentences.

4.  Refer to your notes or your understanding about osmosis.   Explain WHY you got these results.  Write in complete and thoughtful sentences. 

5. Supermarkets regularly spray their vegetables with water. Why would this improve the quality of vegetables sold at the store?

6. Construct a model showing what is happening int he cells of a carrot that is placed ina hypotonic solution.