Saturday, February 11, 2012

Lab Project: Milk, Juice, Carrot

Introduction: We are to take 1/2 cup of milk, pour it into a jar or glass and put it into a warm, dark place for two days. We are to observe any changes in the milk due to biological influences. Proteins are critical as well as the fermentation process and carbohydrates.

Hypothesis:  I believe the bacteria in the milk, once the temperature gets warmer, will start to grow. First the milk will turn sour or ferment and eventually it will get clumpy. If enough time passes, we would eventually see mold. But I do not believe that will happen this quickly.

1/2 cup of milk
milk in glass
milk in dark place
Procedure: I poured a 1/2 a cup of 2% milk into a small glass. I then placed it in a file cabinet and shut the drawer for a period of two days.

Results: There was film scum on the edges of the milk in the glass. It was sour to taste (I dabbed my finger into it). But no clumping yet and no mold.

Conclusion: A conversion of carbohydrates to alcohol and sugar to lactic acid occurs. Bacteria, called coliforms exist in milk. It metabolizes or ferments sugar to gain energy in order to grow and multiply. This process will continue until there is no sugar left. Coliforms include E-Coli. (As a side note: Pastuerization reduces the level of coliforms). Once all the lactose is consumed, the bacteria breaks down the protein to form amonia (the base pH of milk). The protein in milk denatures or loses their shape and clumps form together.

Lab Project: Milk, Juice, Carrot

1/2 cup of juice

Introduction: We are to witness the mixing action of molecules and describe the process. We take 2 cups of room temperature water, two cups of ice water and two cups of boiling water into separate cups or jars. Then we take a 1/2 cup of a dark juice and pour a third of this into each cup of water.The temperature of the water will have a definite impact on the way the molecules mix.
room temp juice/water
room temp water

ice water/juice

ice water/juice

broken glass
Hypothesis: I believe the temperature of the water will have a serious impact on how these molecules mix. Not sure what it will do, butI think hot water will mix fairly quickly, cold probably not so muchand room temperature may not have any effect.
boiling water
boiling water/juice

  Procedure: I first poured the juice into a measuring cup. Next, I poured room temperature water into a glass and proceeded to pour a third of the juice into this glass. Next, I poured cold ice water into a glass and them followed with another third of the juice. Then, I boiled 2 cups of water and poured that into a glass, at which point the glass cracked and the water leaked out. So I had to start all over, boil more water and then poured it instead into a measuring cup and then followed this with the remaining juice.

Results: In the room temperature water and juice combo, I did not notice much of anything. The mixture mixed fairly well, but was cloudy. When I mixed the ice water and juice, the juice sunk to the bottom and bubbles appeared on top. When I poured the boiling water into the glass, my glass cracked and all the liquid leaked out. So I redid, and poured it into a measuring cup and then added the remaining juice. Last, but not least, when I managed to combine the boiling water and juice, it mixed very quickly and was a fairly clear solution.
Conclusion:  The room temperature water had very little effect on the mixing action of these molecules compared to the ice and boiling water. When I mixed the ice water and juice, the moving action of the molecules was very slow. When the boiling water was poured into the glass, it broke because the inner surface of the glass gets the heat first and expands more quickly than the outside. The sudden pressure from the heated inside is so strong and sudden that the whole glass breaks. Once I managed to add boiling water and juice, the hot water caused the mixing action to speed up and molecules mixed quickly.

Lab Project: Milk, Juice, Carrot

Introduction: The objective of the carrot lab is to investigate the cellular functions and cellular structures using a carrot in both fresh water and salt water.

whole carrot
cut in half
Hypothesis: I believe that the carrot in the fresh water will swell  after soaking and the carrot in the salt water will either remain the same or shrink. The fresh water will probably diffuse into the carrots cells and just the opposite with salt water.

original measurement
Procedure: We were to pour two cups of water into two glasses or jars. In one cup was added a teaspoon of salt. Then I labeled them, "fresh" and "salt" respectively. I cut a carrot in half and measured both pieces in height and width. Then I tied a string around the cut end of each piece and put them into their water to soak for 24 hours.
glasses labeled

soaking overnight

Results: The initial width of the salt water carrot was 3/4" and the
height was 4 11/16". After soaking for 24 hours, the width and height were the same. So the salt water maintained the carrots size. The beginning width of the fresh water carrot was 3/4" and the height was 4 5/8". After soaking 24 hours, the width was 13/16" and the height was 4 11/16". So the carrot expanded by 1/16 of an inch both in width and height. 

measurement afterward

Conclusion: Osmosis is the diffusion of water through a membrane. A carrot is made up of tiny cells surrounded by cell membranes. The cell membrane keeps cell parts inside and protected. While this membrane stops most things, water can pass through it. Water moves through cell membranes towards a higher concentration of dissolved chemicals. When the carrot is soaking in salt water,  the water found in the carrot's cell will move into the salty water to equalize the amount of water inside and outside the cells' membranes. As more and more of the cells lose water, the carrot becomes soft and flexible. When the carrot is placed in the fresh water, the reverse happens. The fresh water around the  carrot moves into the carrot's cells. The string will tighten and the carrot will swell with water.

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