Frog Dissection

On Tuesday and Wednesday we had the unique opportunity to dissect frogs in our class lab groups, and boy, what an experience it was! After making sure we understood the instructions, we jumped right in! The first day we didn't do much, except for cutting through the skin and muscle on the ventral side. Once we did, it opened a door to reveal all of the organs, and of course-tons of preservatives! On a side note~the frogs didn't smell half as bad as I thought they would. Not that they didn't smell bad at all, because believe me, they did, but the stench was still bearable, a definite plus. Once we cut through, this is what our frog (which we named Crystal) looked like (see picture one). To prepare for the next day, we took out Crystal's eggs (because she was female). They were very small, black, and round. There were way more eggs than I thought there would be! There must have been hundreds of them all sitting there, spread across the entire frog!  The fat bodies really did look like spaghetti, just like our packet said.                               

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Our frog after cutting through the skin and muscle

Fat bodies

          


















On the second day we discussed all of the organs on the packet we got and described their functions. As we watched Mrs. Rousseau dissect the frog, I was able to clearly see each organ and where it was located (Thanks Mrs. Rousseau-you're the best!). When it was our turn to dissect, my group first thought that the liver was the lungs, and we were surprised to find out that it was not. Who would have known that the liver was the largest organ in the frog's body? Once we pinned the skin to the side the organs looked like this: 

It was fun looking at each organ and being able to identify it. The frogs have similar organs to humans, so I found it interesting to compare. For example, even though frogs and humans both have a gall bladder, the frog's looks like a giant green booger (there is really no other way to describe it). Labeling the organs in a diagram on paper further enhanced our knowledge of their placement. Overall, dissecting a frog allowed us to compare ourselves with frogs and determine the different life systems in a frog (And we got to have a blast while doing it! Thanks Crystal!) 


While writing this I came across websites that added to my understanding, or gave me a chance to do a virtual dissection, so I decided to share:
http://www.hoala.org/marine%20biology/frog%20dissection.html  
http://frog.edschool.virginia.edu/Frog2/home.html
http://froggy.lbl.gov/cgi-bin/dissect?engl


Or if you are daring enough, take the quiz:
http://biology.about.com/library/weekly/bl1qfrog.htm
                                                                                                              
                                                     

As the Stomach Churns

On November 7th and November 8th we worked in small lab groups to conduct an experiment to see how our stomach works when digesting foods.  We investigated how acidic conditions affect protein digestion. Through this lab we were able to see how hydrochloric acid functions in order to digest proteins. Through our data chart we noted the appearance of the contents in our test tubes, and what reaction the contents had when placed on Litmus paper. We came to the conclusion that hydrochloric acid breaks down the proteins, and that it has a very low, acidic pH level. We also discussed the different pH levels, acidic, alkaline, and neutral.

Chicken Wing Dissection

On Thursday, October 20th we observed a chicken wing being dissected in class. We were able to identify different types of tissues and identify the organs. During class we were able to make connections on how we were similar to the wing, and how we were different. Because the wing dissection was put up on the smart board, we were clearly able to see the color, texture, and what tissue each part of the wing was connected to. The chicken wing anatomy activities also helped us to fully understand what we saw.

Diffusion lab

On Tuesday, October 11^th we conducted an in-class experiment to demonstrate the process of diffusion and osmosis and how the iodine molecules were able to go through the selectively permeable membrane to turn the corn starch purple. The purpose of this lab was to see how a cell membrane functioned, being selectively permeable and allowing certain molecules to go through it. The materials used were able to effectively show the process of diffusion and osmosis. Common predictions made were about what would happen if the baggie was permeable to certain materials. An example of one prediction made was that the iodine used would move out of the bag if it were permeable to starch. Another prediction was about what color certain solutions in the baggie and beaker would turn. During this lab, we tried to figure out which area, the baggie or beaker was hypertonic, (higher concentration) and which was hypotonic (lower concentration) We also tried to notice what substance would be the indicator, making a distinguishing change, and what substance would dilute (make less concentrated) the iodine mixture in the beaker.  One thing noticed was that after the diffusion and osmosis occurred, the solute concentrations were isotonic, or equal in solute concentrations.

This lab proved that while the iodine molecules went from a higher concentrated area in the beaker to a lower concentrated area in the baggie that the iodine proved to be the indicator, because the corn starch in the baggie turned a shade of purple when combined with the iodine, or indicator. This lab also showed that adding more water to a concentrated area such as the one in the baggie will dilute it, or make it less concentrated, turning the solution in the baggie a lighter color due to it being diluted. It also showed that the iodine moved. This was determined by the starch turning purple when in contact with iodine. We were also able to see which substances the plastic baggie was permeable to, which was iodine.

The process of diffusion and osmosis can be related to everyday occurrences. For example, the most popular process of diffusion would be with tea. When a tea bag is placed in a cup of water, the water turns a different color due to the insides of the tea bag diffusing throughout and giving it color and taste. A second example would be a helium balloon. On the first day the balloon is full of helium and floats in the air. As the days go on, the balloon slowly loses its helium and falls to the ground.  By doing this, the concentration becomes equal on both sides. One example of osmosis is putting a limp vegetable in water. Through the process of osmosis the limp vegetable is revived because the water is reentering the vegetable through the process of osmosis. Another example is leaving your hands in dishwater for a long period of time. Although the skin looks shriveled it is actually just bloated, due to osmosis. 

Diffusion Lab

Today in science class we worked on a diffusion lab. We used corn starch, water, and iodine to help us learn. The purpose of our diffusion lab was to be able to recognize the process of diffusion and osmosis.  We also discussed permeable membranes to answer why our results occurred. In class, we were able to define key terms such as diffusion, osmosis, and indicators. We recognized what role each part of our lab had to do with our finished product. Publish Post