Unit 3 Reflection

            This unit was all about cells and their different parts, photosynthesis, and cellular respiration. Some themes and essential understandings were that cells are the basic unit of life, photosynthesis is the main source of energy for plants, and that cellular respiration has three main steps. Some of my strengths is understanding how diffusion occurs and knowing all of the parts of the cell. One of my weaknesses is fully understanding the process of photosynthesis. I also have trouble memorizing all the jobs of the different parts of the cell. One success of mine is being able to identify all the parts of the cell because I studied a lot to try and memorize them. However, a setback of mine is not being able to understand photosynthesis well because it is a big concept and very important in biology. The two hardest topics to understand are cellular respiration and photosynthesis. I still do not fully understand photosynthesis. I learned that in order to manage the demands of the class well I have to study for tests by reviewing by notes as soon as I'm done with the vodcast to recap all the information in my notes. I learned that I work well in collaborative settings.
            In this unit we learned about the history of cells and their different parts and functions. We learned the differences between plant cells and animal cells. We also learned about photosynthesis and cellular respiration. The reactants and products of cellular respiration and photosynthesis are opposites. We were taught the equations for both photosynthesis and cellular respiration. The three main parts of cellular respiration are glycosides, the Krebs Cycle, and the electron transport chain. In addition to learning about photosynthesis and cellular respiration we also learned about diffusion and the different types of diffusion. Facilitated diffusion uses no energy while active transport requires a lot of energy. Some other things we learned were the levels of organization, unicellular and multicellular organisms, and osmosis.
            I want to learn more about cellular respiration. I don't have any unanswered questions, but I still have to study more for the test in order to be prepared. I wonder about whether we can see a cell during the process of photosynthesis or cellular respiration. In order to study for the test, I am reviewing my vodcast notes and reading my textbook notes. I have not looked at the Studying and Learning page but I am planning to soon. I am planning to highlight all the key ideas and points in my vodcast notes in order for me to understand and remember it better.

Egg Diffusion Lab

            In this lab, we asked the question "how and why does a cell's internal environment change, as it's external environment changes?" For this experiment, we submerged two eggs into vinegar and let them sit for a few days. Then, we took both of them out and measured the mass and circumference for both. We then put one in corn syrup and another into water. We let them sit in the solutions for two days and then measured them again. We found that the egg grew bigger when submerged in deionized water and shrunk when it was put in sugar water, or corn syrup. The corn syrup was a hypertonic solution while the water was a hypotonic solution. When the sugar concentration increased, the mass and circumference of the egg decreased. The class average showed that the mass of the egg decreased by 47.25% and the circumference decreased by 22.94%. Because the solutes can't move into the egg due to the membrane, the solvents had to move out to balance the amount of solvents and solutes inside and outside. The solvents diffused out of the egg because the molecules move from high concentration to low concentration.
            A cell's internal environment changes as its external environment changes because the solvents diffuse either into or out of the cell to try and balance the amount of solvents and solutes. The solvents, water, inside the cell would passively diffuse out of the membrane if put in corn syrup, but if put in water, the water from outside the cell would diffuse into the cell. Because of the water either moving into the cell or out of the cell, it would either shrink or expand. The addition of vinegar caused the egg's shell to dissolve and soon expand. When putting the egg in water, the egg expanded due to diffusion. The water moved into the membrane making the egg a bigger size. However, when the egg was put into the sugar water, it shrunk because of the water moving out of the membrane.
            This lab is a great demonstration for diffusion because it shows the physical changes of what would actually happen to the cell. It shows the egg shrinking and expanding based on the different solutions it was put in. Fresh vegetables are sprayed with water at markets in order to prevent them from wilting. If water is sprayed onto the vegetables, they will stay fresh for longer because the water will diffuse into the vegetables and prevent them from shriveling up. The salting of the roads kills the roadside plants because the plants diffuse water out of the membrane. It shrivels up and stops functioning causing them to die. Based on this experiment, I would want to test an egg that has been put in sugar water first, and then try putting them back in pure water to see if it would expand and go back to their normal mass and circumference.

Egg Macromolecules Lab Conclusion

In this lab we asked the question “can macromolecules be identified in an egg cell?” We found that macromolecules can be identified in egg cells by using special indicators. We used benedict’s solution, iodine, Sudan III, and sodium hydroxide to identify macromolecules in the egg cell. We found that the egg yolk had proteins, the egg membrane had polysaccharides, and the egg whites had lipids. When we added sodium hydroxide to the yolk, the color turned a light purple. The egg yolk had many proteins present because the color changed from yellow to a light purple color. In egg yolk, there is lots of protein because the chick needs a lot of energy to develop its tissues and organs. We rated the quantity of proteins present in the egg yolk a seven out of ten. When we added iodine to the egg membrane, we noticed that it turned to a very dark yellow then to an almost brown color. We rated the quantity of the polysaccharides present a six out of ten. Polysaccharides would be present in the egg membrane because polysaccharides are in the cell membrane, they are actually the carbohydrate chains. Lastly, we found that the egg whites contained lipids. We added Sudan III to the whites and we saw the color change from a whitish pinkish to a light orange. We rated the quantity of lipids present a five out of ten. There would be lipids present in the egg whites because it needs a lot of energy for growth and development. This data supports our claim because we had the correct color changes and there are clear reasons why the macromolecules would be present in the specific parts of the egg.

While our hypothesis was supported by our data, there could have been errors due to the different parts of the egg not being completely separated from each other and the amount of indicators put into each test tube. If the yolk, membrane, and whites were not separated perfectly, then some of them could have tested positive for macromolecules when in reality they were just different parts of the egg that were testing positive. The amount of indicators put into each test tube were also very important roles in getting the most accurate data. The amount of indicators put into each test tube differed from one another because one person could have accidentally put five drops of Sudan III instead of three or maybe they could have put bigger drops of the indicator in. Due to these errors, in future experiments I would recommend separating the yolk, membrane, and whites perfectly and having one person put the indicator into the test tubes to make sure they are all the same amount.

This lab was done to demonstrate which parts of the egg contained which macromolecules. From this lab I learned that yolk has lots of protein, whites have lipids, and the membrane contains polysaccharides. This helps me understand the concept of cells and their jobs because it showed which parts of the egg had which macromolecules and why they had those specific macromolecules to help carry out their job. Based on my experience from this lab I could apply this to another situation by using my knowledge to tell athletes which part of an egg to eat if they, for example, want more proteins or lipids in their diet.