Brianna Barkey 1-22/23-13

4(A) Lab Report 3: Osmosis of Human Hair

Introduction: Our class is doing a lab, it's purpose is to model the cells process of diffusion and osmosis and relate this phenomena to the motion of water through the semi permeable membrane. A lot to take in at once, so let me help you. Diffusion is the movement of particles from a high concentration to a low concentration. Osmosis is the diffusion of water through a cell membrane. A cell, which makes up all living things, is the basic unit of life. All cells have a semi permeable membrane which controls what comes in and what goes out. Hypothesis: I am seeing how the cells of a (females) human hair reacts to being in three different substances. They are water, salt water, and soda. In this lab I am guessing the hair cells in the water will be inflated by water and maybe rupture if there is too much water that they can't hold, so it will react with the Hypotonic solution. Now with the salt water the cells will react with Hypertonic solution, where the concentration is higher outside the cell, so the cell shrinks. Now with the soda I highly doubt it will react with an Isotonic solution, which is where the concentration outside is equal to the concentration inside. Here is a picture to help you understand the three solutions of a cell.

Methods: Step 1: Gather these materials:

• hair (about same size) • 3 small test-tubes • salt • water • soda (any kind)

Step 2: Get a test-tube and add in a certain amount of salt (I did 1mL) and then add in some water. Step 3: Then with another test-tube add in the soda, make sure to add in the same proportion (or close) to the amount of water in step 2. Step 4: Get the last test-tube and add in water, same proportion as step 2 and 3. Step 5: Add in hair to each test-tube. Try to estimate the same amount in each tube. Step 6: Let the test-tubes sit for a few days, I let my experiment soak for 4 days. Step 7: Look at the hairs under a microscope. Then compare each hair sample to normal hair from the same person. Step 8: Record data on the differences, look a lot at the size differences, and see what reaction happened: Isotonic, Hypotonic, or Hypertonic.

Results:

Regular Hair Soda Water Salt Water

Initial (Regular Hair) 4 Days Later

Soda

When I looked at the hair under a microscope, the hair strand was normal size.

My best drawing of what I saw is above.

Now with the soda, it looked about half as small as the normal hair. So it slightly reacted to the Hypertonic

solution. It was harder to see the size difference when I looked at it.

Water

When I looked at the hair under a microscope, the hair strand was normal size.

My best drawing of what I saw is above.

The hair soaked in water looked about 1/3 bigger than the regular

hair. So it reacted with the Hypotonic solution. I could

definitely see the change in size.

Salt Water When I looked at the hair under a

microscope, the hair strand was normal size. My best drawing of what I saw is above.

With the salt water I saw that it looked about half the size as the

regular, reacting with the Hypertonic solution. It was easier to see the difference of its size and the regulars size, than it was to see

the soda hair.

Conclusion:

I made my best educated guess on how a hair cell will react in each different substance,

which was soda, water, and salt water. With the soda, my hypothesis was that I thought it would

not react in an Isotonic solution and it was accepted. Now I didn't really know what would

happen to the cell, but it seems it reacted slightly with the Hypertonic solution. I guess all the

sugar sucked out some of the water it held. Now with the water I thought that it would have a

higher concentration of water in the cell than outside of the cell, reacting with the Hypotonic

solution. This hypothesis was accepted, I saw a major difference in size with the regular hair and

the one soaked in water for four days. Last but definitely not least comes my hypothesis on the

hair soaked in salt water, which I thought it would react with the Hypertonic solution, where

water diffuses from the cell to the outside of the cell. It was also accepted, so it seems all three of

the points of my hypothesis was accepted. I infer that the sugar in the soda and the salt in the

water sucked out some water from the cell, thus making it shrink. With the water, the cell sucked

in water and the concentration of the cell grew as more water seeped in through the semi-

permeable membrane.

Now with this lab, an error was that maybe I could not have two different peoples hairs,

because the hairs themselves are different sizes. I compared Miss Walker's hair to my hair,

which could be thicker, so it's not an accurate compare. Something I could have done was have

two peoples hair, but make sure they are compared with the same persons hair they came from.

Or just use one persons hair. Another future idea is that I could also see if there is a difference of

osmosis between male and female hair, but of course I would have to do that when I have

technology to measure the size of each hair. I learned- and memorized- the three solutions of a

cell. Isotonic a happy cell, Hypotonic a cell with a high concentration of water, and Hypertonic a

dehydrated cell. I got to see how a cell looks in each of these solutions. This pertains to our class

because we have been learning about cells, their functions, and how they make up all living

things. I can apply this to my life, it helps me realize that too much soda and salt is bad for the

cells taking care of me, that I have to be careful of those types of food. Many other people could

benefit from this knowledge, and I hope to share this information with others too!