Evidence for Evolution Quiz

1. These four pictures depict a species adapting to go from a land animal, to a marine animal. Its tail transitions into a fin and its front paws turn into fins as well. Its back legs shrink and become useless, but do not completely disappear. This shows that whales and land mammals have homologous bone structures. It also shows that they likely have very similar DNA, which was also seen in the Common Descent Lab. 

2. C) Australia

3. These three species show analogous structures. Each species developed wings, but they each developed separately and each have very different structures despite having the same purpose, to allow the species to fly.

4. The common descent lab showed that two animals seemingly very different, such as horses and chickens, are actually very closely related. Through the differences in DNA you can create a cladogram and see where different animals branched away from each other. The cladogram also shows that different animals all have the same ancestor. DNA evidence shows how similarly related humans are to primates. We have very similar DNA which explains the various similarities we have with primates, such as opposable thumbs, a large brain, and similar digestive systems.

5. Homology is the study of the similarities in the bone structures of two separate species, due to similar ancestry. In "Your Inner Fish" chapter 2 it discussed homologous bone structures between many different species. Most species contain a homologous bone structure in their arms, consisting of one bone, which leads into two bones, which leads into many small bones in the wrist, and then into long bones or fingers. This structure is true for animals from cats, to bats, to humans, to whales. The width and length of each differs, but the same structure is consistent in each.

Evolution

    Today we began with choosing between two different labs. I chose the cladogram lab, where we had to compare Amino acid codes between different animals. The number of differences related to how different the two species are. We then used this information to create a cladogram between all the animals, which shows when different animals branched away and which animals are the most closely related.
    We also discussed different evidence for evolution including homology, embryology, and the fossil record. An example of a homologous bone structure is a bat wing and a cat arm. Both have the same exact bones, but look very different from the outside. Embryology is comparing embryos of different species to see how similar they are before they fully develop. The fossil record shows that in different layers of sedimentary rock, there are different fossils. The fossils closest to the top are more recent organisms, and the ones on the bottom are older organisms. We can see through these fossils the transitions between animals and how different organisms developed to adapt to their surroundings.

Tiktaalik

     Today we discussed Chapters 1 and 2 in "Your Inner Fish." The book was written by Neil Shubin, who discovered Tiktaalik. Tiktaalik is the animal that transitioned from water to land. He made this transition because there was more food and less predators on land. However, he could only come onto land for brief periods of time because he still used gills to breathe. Tiktaalik had the beginning of many animals modern day bone structure in his arm and hand. He also had a very different neck from fish, and had wider ribs. All of these allowed him to become more successful on land and many things Tiktaalik acquired, we still have today, such as wider ribs, a neck, and arm bone structure. 

A model of Tiktaalik in our museum

Jerell's iPod

     Today in class we started off by discussing macromolecules, hydrolysis, monosaccharides, like glucose, galactose and fructose, disaccharides, like sucrose, maltose and lactose and polysaccharides, like starch. We used this knowledge in our lab, in which we had to determine who had stolen Jerell's ipod based off the food evidence left at the scene. We began by testing known by testing basic substances, such as proteins, starches, and lipids. After this we tested basic foods, like pretzels, beans, jelly and butter. Then we tested both liquid and dry evidence found at the scene and compared our results to what each of the suspects had for lunch. We used the following substances to test for a reaction:
1) Iodine -  tested for starch
2) Benedrict's - tested for glucose
3) Biuret - tested for protein
4) Sudan III - tested for lipids

House Case #1

     Today in Biology we did our first house case. The patient was an 18 year old male who ran cross country at The Webb Schools. After running cross country he became very nauseous and dizzy and threw up. He then woke up at the hospital very confused. My initial hypotheses for what he had were 1) Diabetes, 2) Heat Exhaustion, and 3) Dehydration.
     During class Mr. Quick acted as the patient and each student got to ask two questions. Through these questions we discovered more about his symptoms and what they could have possibly stemmed from. We discovered:
1) He had vomited (water and lunch)
2) He had severe headaches
3) He had taken no medications
4) He did not have a history of headaches
5) He was extremely tired
6) He had memory loss and was confused
7) He had gotten 6 hours of sleep
8) He had no head trauma
9) The last meal he had was lunch (chicken and rice)
10) He sweated during his run
11) After practice he fainted
12) Drank 3 Gallons of water
     After this we were allowed to run certain tests on the patient and discovered only a few things unusual. It became clear that the patient had drunk too much water (3 gallons) and we diagnosed him with over-hydration.

Diffusion and Osmosis Lab Day 2

     Today to begin class we talked about three of the different shapes that cells can take, cuboidal, columnar, and epithelial. We also talked briefly about the splitting of a cell, called mitosis. After this discussion we began part two of our lab. Mr. Quick handed out pieces of "cell" which was really a type of solid jelly.We cut the substance into the three distinct shapes we learned about and measured the surface area and volume of each. After this we put each cell into a different beaker with KI in it, a dark colored starch. After 15 minutes we took the cells out and examined them to see how much the KI had diffused into them.

     After this we placed a cell that contained 15% glucose and 19% starch into a beaker containing water and a drop of Benedricts. We saw the color change within the cell as it turned blue because the glucose left but the starch stayed, and this starch reacted with the iodine to create the blue color.

Diffusion and Osmosis Lab Day 1

     Today we began by discussing the difference between Osmosis and Diffusion. Osmosis is the movement of water through a semi-permeable membrane of a cell to a higher concentration solution to try to equalize them. Diffusion is when particles move from higher concentration to lower concentration.
     After this discussion we did an osmosis lab that had three different parts. In the first part we created our own "cells" by putting different color and molarity fructose water into bags that act as cell membranes, and placing these in distilled water. Afterwards we found the percent change and discovered which molarities went with the different colors based on how much mass each of them gained.

     In the second part of this lab we put Poweraid into baggies and put the baggies into different molarity fructose waters. We calculated the mass change of these to see which substance had a higher concentration.

     In the third part we put sweet potatoes into different fructose waters and calculated mass change to see which substance had a higher concentration.

Properties of Water

     Today in class we reviewed the properties of water and talked about why those properties make water such a vital substance. The first property about water which makes it important is its high heat capacity, which allows water to absorb a high amount of energy without changing phases, so it moderates the earth's temperature. Water's polarity, the hydrogen atoms being slightly positive and the oxygen atoms being slightly negative, allow for cohesion and adhesion. Cohesion is water's tendency to bond with other water molecules, which leads it to have a high surface tension and leads it to fall in drops instead of in individual molecules. Adhesion is water's tendency to bond with other substances, for instance a paper towel. This property explains why paper towels can soak up water so easily and why water will climb up a straw. This tendency to climb up narrow tubes is called capillary action, which is vital to the ecosystem because it is why water climbs up plants' tubes. Another important property is water's ability to become less dense when it freezes, because the hydrogen bonds expand to have less mass per volume. Because the top layer of water freezes and floats, it allows for marine life to survive underneath the frozen surface.
     Later in class we did an short experiment to demonstrate cohesion. We each had a penny, a pipette, and a beaker of water. We saw how many large drops of water could be placed on the penny before the surface tension was broken. We did this twice and took the average, and then the third time we put the average number of drops and did it a third time using that number. 

A penny experiencing cohesion, 27 drops of water

After the correct number of water drops was on the penny, we observed what would happen if we touched the surface of the water with a toothpick. We observed adhesion, the water went up to meet the toothpick and bonded with it.

The water adhering to the toothpick

 After this we dipped the toothpick in detergent and touched the surface to see what would happen. This broke the surface because detergent is a surfactant, so it broke up the bonds in the water.

After touching the water with the surfactant