Objectives:

1.  Students will use carrots as cell models and demonstrate diffusion and osmosis, by measuring and observing the changes in the mass and size of the carrot.

Materials:

·  Two cups

·  string

·  measuring tape or meter stick

·  salt

·  water

·  triple beam balance

·  carrots

Procedures:

1.  Take your day 1 measurements. See data tables. Fill two cups with 100 ml of each solution. Solution A salt water and Solution B tap water

2.  Cut a carrot in half. Tightly tie a piece of string two cm below the cut end of both pieces.

3.  Place one carrot half (cut end down) in one cup. Be sure to label with your group color and period. Label the cup "Salt Water". Place the other carrot with cut end down in the "Fresh Water" cup. Allow carrots to remain undisturbed for 24 hours.

4.  Form your hypothesis. Be sure to use correct format

5.  After 24 hours remove the carrots and observe them and the tightness of the strings. Record data data.

6.  At the conclusion of your experiment, answer the following questions (realize that some require deeper thinking than others?

Hypothesis:______

Data Table:

Quantitative Observation

Quantitative Observation / Carrot in Salt Water / Carrot in Tap Water
Day 1 mass (grams)
Day 2 mass (grams)
Quantitative Observation / Circumference of carrot / Circumference of carrot
Day 1 circumference
Day 2 circumference

Graph:

1.  Create two graphs:

Graph A: Mass

Graph B: Circumference

Post Lab Questions (results): Complete sentences

1.  Describe what happened to the thread in fresh water. Salt water.

2.  In which type of water did the carrot cells increase in cell size (freshwater or salt water? (What evidence supports your response?)

3.  In which type of water did the carrot cells decrease in cell size (freshwater or salt water? (What evidence supports your response?)

4.  In potatoes/carrots, what cell part stores water?

5.  How do you predict human blood cells would be impacted if they were placed in a beaker of salt water?

Extended Writing:

Compare and contrast the processes of diffusion and osmosis. Why are both of these processes important in cells maintaining homeostasis (stability)? If cells did not have these processes how would this impact the body? (7 or more sentences)