Lab Projects

Part I     Milk

Objective:  Observe and explain changes occurring in milk due to biological influences.

Hypothesis:  I believe the milk will spoil, because of the biological influence of bacteria. Due to the heat, the bacteria will multiply creating a foul smell caused by acids emitted from the bacteria.

Procedure:  Pour ½ cup of milk into a cup and place in a warm, dark place for a few days.

Results:  The milk had a top layer that began to clot.

Conclusion: Bacteria entered the milk and began eating the sugar (lactose) for energy and to reproduce. The bacteria than began to push out the lactic acid molecules out of the cell. The lactic acid molecules reacted chemically with the protein molecules in the milk and the protein molecules began to stick together. This is the top layer of the milk that began to clot.

Part II    Juice

Objective:  Witness the mixing action of molecules and describe the process.

Hypothesis:  My thoughts are that the molecules will mix gradually with the two cups of water that are room temperature, because heat increases the mixing of molecules. Since the water is at room temperature, the molecules will mix gradually and the diffusion of the molecules will move smoothly and from high-concentration to low-concentration.

The molecules will mix very slowly with ice water, because when molecules are cold they slow down.

The molecules will mix almost instantaneously with the boiling water because of the heat the molecules move faster.

Procedure: 

1.     Pour 2 cups of room temperature water in cup.

2.     Pour 2 cups of ice water in cup 2.

3.      Pour 2 cups of boiling water in cup 3.

4.     Slowly pour 1/3 of the juice into cup 1.

5.     Repeat step 4 with cup 2 and 3.

Results: When I poured the 1/3 cup of juice into the cup with 2 cups of room temperature water the mixing of molecules was quick.

I noticed when I poured the juice into the cup with the 2 cups of ice water I gradually saw the mixing of molecules start from the top and move down.

When I mixed the juice into the cup with 2 cups of boiling water, the mixing of molecules was instantaneous.

Conclusion:  I reached a conclusion that molecules are temperature sensitive. If the solution is hot, the molecules move faster and mix quicker; if the solution is cold, the molecules move very slowly. There were similarities with the mixing of molecules between the water that was room temperature and the boiling hot water. The molecules moved very fast.

Part III   Carrot

Objective: Investigate cellular functions and cellular structures using a carrot.

Hypothesis: I believe that the carrot in the salt water will reduce in size, because the molecule is trying to reduce the salt by diluting it with its water causing the molecule to shrink.

The carrot in the water without the salt I believe will swell due to the water diffusing into the molecule.

Procedure: 

1.     Pour 2 cups of water into 2 cups or jars.

2.     Add 1tsp of salt into 1 cup and label “salt water”.

3.     Label the other cup “fresh water”.

4.     Cut a fresh carrot in half. Measure the length/width of both pieces and record this on the answer sheet.

5.     Tie a piece of string just above the cut side of the carrot on both pieces. Tie tightly.

6.     Set 1 carrot with the cut end side down into 1 cup and the other cut end side down into the other cup.

7.     Leave for 24hrs.

Initial Length/Width of Carrot Pieces:

	Length	Width
Fresh Water	4 3/16	15/16
Salt Water	3 3/8	15/16

After Experiment Length/Width of Carrot Pieces:

	Length	Width
Fresh Water	4 1/8	1”
Salt Water	3 1/2	14/16

Results: The carrot in the fresh water shrunk 1/16 of an inch and increased in width by 1/16 of an inch.

The carrot in the salt water grew by 1/16 and the width decreased by 1/16.

Conclusion: My conclusion is that the carrot in the fresh water increased in width by 1/16 of an inch due to the water diffusing into the molecule. The carrot shrunk 1/16 of an inch because the tip of the carrot was sticking out of the water and was shriveled up by the end of the project. The string I tied to this carrot was still tight.

The carrot that was in the salt water decreased in width by 1/16 of an inch due to the molecule trying to dilute the salt, however I do not understand why it grew in length. That must be operator error. The string I tied to this carrot fell off as soon as I lifted the carrot out of the water.