Unit 3 Reflection

In a nutcell (nutshell), this unit was about cell structure and function, photosynthesis, and cellular respiration. Some of the themes included the process by which a protein is created, a tour of the cell, the reactants and products of both photosynthesis and cellular respiration, etc.

Although many of the concepts and skills required in this unit were already fairly familiar to me, I had quite a bit of trouble memorizing and fully grasping all of the structures and functions of all the organelles within a cell as well as many of the complex steps in the reaction of cellular respiration.

I am definitely a better student now than I was at the beginning of the unit. I have learned many new skills such as focusing a microscope on the specimen much more quickly, I also learned how to make cool labels on Google Drawing. But most importantly, I started to get more accommodated to working with my tablemates and getting to know them better, making our labs much more efficient and at the same time, fun.

Photosynthesis Virtual Labs

Photosynthesis Virtual Labs.

Lab 1: Glencoe Photosynthesis Lab

http://www.glencoe.com/sites/common_assets/science/virtual_labs/LS12/LS12.html

Analysis Questions

1. Make a hypothesis about which color in the visible spectrum causes the most plant growth and which color in the visible spectrum causes the least plant growth?

Since in the vodcasts, it said that plants grow best under red or blue light, my hypothesis is that if a plant is that if a plant is put under red or blue light, then it will have the most plant growth.

Also, plants reflect green light, so my hypothesis is that when put under green light, plants will have the least growth.

2. How did you test your hypothesis? Which variables did you control in your experiment and which variable did you change in order to compare your growth results?

I tested my hypothesis by putting the same plant under different wavelengths (colors) of light. For my control, I used white light, as it contains all the different colors and acts as a good base measurement of how much the plant should grow. The variable I changed was the color on the left side, so I could compare it to normal while light and see what would happen.

Results:

Filter Color	Spinach Avg. Height (cm)	Radish Avg. Height (cm)	Lettuce Avg. Height (cm)
Red	18	13	11
Orange	14	8	6
Green	2	1	3
Blue	19	14	12
Violet	16	10	8

3. Analyze the results of your experiment. Did your data support your hypothesis? Explain. If you conducted tests with more than one type of seed, explain any differences or similarities you found among types of seeds.

My data definitely supported my hypothesis. All the seeds that grew under the same color of light ended up having pretty consistent heights. The plants that grew under the blue lights and red lights were always significantly and consistently taller than those that grew under violet or green light.

4. What conclusions can you draw about which color in the visible spectrum causes the most plant growth?

The color in the visible spectrum that causes the most plant growth is without a doubt blue. The height of the plants that grew under blue light always exceeded the height of those that grew under other colors.

5. Given that white light contains all colors of the spectrum, what growth results would you expect under white light?

I think that when the plants are placed under white light, which contains all the colors of the spectrum, the growth of the plants would be similar to that of the plants that grew under violet light--not quite as tall as plants under blue or red light, but taller than those that grew under orange or green light.

Site 2: Photolab

http://www.kscience.co.uk/animations/photolab.swf

This simulation allows you to manipulate many variables. You already observed how light colors will affect the growth of a plant, in this simulation you can directly measure the rate of photosynthesis by counting the number of bubbles of oxygen that are released.

There are 3 other potential variables you could test with this simulation: amount of carbon dioxide, light intensity, and temperature.

Choose one variable and design and experiment that would test how this factor affects the rate of photosynthesis. Remember, that when designing an experiment, you need to keep all variables constant except the one you are testing. Collect data and write a lab report of your findings that includes:

• Question
• Hypothesis
• Experimental parameters (in other words, what is the dependent variable, independent variable, constants, and control?)
• Data table
• Conclusion (Just 1st and 3rd paragraphs since there's no way to make errors in a virtual lab)

*Type your question, hypothesis, etc. below.  When done, submit this document via Canvas.  You may also copy and paste it into your blog.

Question: How does the amount of carbon dioxide in system contribute to the amount of oxygen produced by photosynthesis?

Hypothesis: If carbon dioxide is required for a photosynthesis reaction to happen, then more carbon dioxide will cause more photosynthesis and therefore produce more oxygen.

Experimental Parameters: The independent variable is the amount of carbon dioxide and the dependent variable is the amount of oxygen produced. Some constants include the amount of light, color of light, the amount of water, the type of plant, the amount of time, and the temperature. The control was no carbon dioxide.   

Amount of Carbon Dioxide	Trial 1 (bubbles in 20 sec)	Trial 2	Trial 3	Average
None added	16	16	16	16
Some added	28	28	28	28

Conclusion: In this lab, I asked the question: How does the amount of carbon dioxide in system contribute to the amount of oxygen produced by photosynthesis? I found that it greatly increases the amount of oxygen bubbles created, almost doubling the amount without carbon dioxide. When I didn’t add any extra carbon dioxide to the system, only 16 oxygen bubbles were produced in 30 seconds while in the system with extra carbon dioxide, there were 28 oxygen bubbles. This is likely because of the fact that carbon dioxide is required to start a photosynthetic reaction. Adding more carbon dioxide gives the plant more reactant to work with, which is most likely the cause of why there is way more product.

This lab was done to demonstrate how different environmental factors affect the process of photosynthesis. From this lab, I learned that more carbon dioxide produced more oxygen, which helps me better understand the concept of the chemical reaction behind photosynthesis. Based on my experience from this lab, if I am a botanist in the future, I might leave my plants in an area with higher concentrations of carbon dioxide to help them grow better.

Microscopic Organism Analysis

Amoeba: We were able to identify the nucleus, the cell membrane, and the pseudopods. This was examining while the power was at 400x. What was unique about the cell was that it had two nuclei and an observation we made was that it was very pink and skinny. The cell is eukaryotic.

Cyanobacteria: We were able to identify the occurrences of a single cell.

Euglena: We were able to identify the nucleus and chloroplasts. The power on the microscope we were using was at 400x. Unlike the circular cell that most of us are used to, the shape of this one was more like a dash, which made it pretty unique. Some observations we made included that it was light blue with dark blue dots which were probably the nuclei. The cell is eukaryotic, as it has a nucleus.

Bacteria cell: We were able to identify the coccus, bacillus, and spirilum.

Ligustrum: We were able to identify the chloroplasts, the epidermis cell, and the vein. This was with the microscope power at 400x. What is unique about this cell is that there are many circles seemingly chained together, giving it an almost artistic design. We observed that there was no nucleus, meaning it is a prokaryotic cell, and therefore, an autotroph.

Muscle Cell: We were able to identify the Striations and the Nucleus. This was with the microscope power at 400x. What is unique about the cell is that there seem to be many organelles clumped together. We observed that it even looks like real muscles, which is pretty intuitive. The muscle cell is eukaryotic and is heterotrophic.

Spirogyra: We were able to identify the cell wall, the chloroplasts, and the pyronoid. This picture was taken with the power on the microscope at 400x. What's unique about this cell is that it is very, very green. Also, it looks kind of like a caterpillar. This plant cell is eukaryotic and is autrophic because it provides for itself its own energy using photosynthesis.

Questions:

In this lab, we examined many different types of cells under the microscope and compared and contrasted the differences between the characteristics that cells belonging to different groups had. We compared and contrasted those which were eukaryotic or prokaryotic and those that were autotrophic of heterotrophic. Some common characteristics among the autotrophs included that they were mostly green and were plant cells. Some characteristics of the heterotrophs were that they were not green, and were usually animal cells with nuclei. They were mainly eukaryotic. The eukaryotic cells were usually the cells in which we were able to identify the nucleus. This is most likely because of the fact that all eukaryotic cells have a nucleus, while prokaryotic cells don't. The prokaryotic cells usually had pretty odd shapes that were very different from the eukaryotic cells. For example, the ligustrum was made of many multicolored rings and the bacteria cells had many floaty squiggly things known as spirillum.

Egg Diffusion Lab

1) The mass and circumference of the egg radically decreased when the egg was placed in sugar water for 24 hours. This is because in an effort to balance out the solute concentration, water came out of the egg to balance out the ratio of solute to solvent. The sugar water is a hypertonic solution, as there is a higher concentration of solute outside of the egg cell. In order to lower this high concentration, water had to flow out of the egg cell to equalize the concentrations.

2) A cell's internal environment changes in many ways in reaction to its external environment. Losing or gaining water by means of diffusion is just one of the ways a cell changes in reaction to its environment. Also, when we soaked the egg in vinegar for 48 hours, the egg's membrane was softened and slightly separated from the white and yolk.

3) This lab demonstrates the principal of osmosis and diffusion. The places where there was a lot of solvent but not enough solute went into the areas of higher solute concentration. In the case with the egg cells, water from within the egg flowed out to balance out the high concentration of sugar, causing it to shrink, while when it was placed in pure water, there was actually a higher solute concentration within the egg, causing water from outside to rush into the egg.

4) Fresh vegetables are sprinkled with water at markets because they want diffusion to occur. When diffusion occurs, the water will soak into the vegetables, keeping them juicy and yummy. Roads are salted to melt ice because when there is a higher concentration of solute (salt) outside of the ice, water will rush out to balance out the concentrations, making the melting point of the ice much lower, so that it is easier to drive during the winter.

5) After this experiment, I want to see if the same diffusion process applies for other cells, not just an egg cell. For example, I might test this kind of experiment on a growing plant. Most likely, we will see the same general idea of changes. The cell will probably shrink in sugar water and grow in pure water.

Egg Macromolecules Lab

In this lab, we asked the question: Can macromolecules be identified in an egg cell? We found that indeed there was a testable way to determine whether or not the specified macromolecules were present in that part of the egg cell. We found that there was a pretty large amount of proteins in the egg white, as the sodium hydroxide and copper sulfate turned a dark purple, signaling a large presence of protein in that area. This is most likely true because according to the nutrition facts, 85% of calories in an egg white come from proteins. This data supports our claim because it shows that there is a lot of protein in an egg white and indeed that this hypothesis was testable.

Part of our data contradicts the expected results because in our tests for monosaccharides and polysaccharides, there was little presence of those. This is most likely because in a rush to finish the lab, we didn't wait long enough for the Benedict's solution or the iodine to sink in and change color. Also, while this part of our hypothesis was supported by our data, there could have been errors due to human perception of color. Especially for the protein tests, the colors looked very similar, so we could only approximate numbers that the whole group agreed which could have skewed the actual results. I recommend that next time, we get more time for the lab, so the window of opportunity for the solutions to change color is larger. Also, I recommend that next time, we should have more bottles of the solutions so that there aren't just a bunch of people waiting in line to add the solution into their test tubes.

This lab was done to demonstrate the presence of macromolecules in cells, like an egg cell for example. Most of what we have learned so far about macromolecules seems pretty abstract, but now that we know more about the practical uses and being able to find these macromolecules in a real life object, it enhances the learning process. From this lab, I learned more about the basic structure of a cell and what macromolecules may appear in these parts of the cell. It helps me better understand the concept of the different functions that different organelles have within cells. Based on my experience from the lab, maybe for a future experiment, we could examine a plant cell and see the differences between the two different types of cells and the macromolecules present in them. Also, with this new information, I now know better how to "dissect" an egg, which could possibly help with later dissections, such as the pig dissection.