Protista Lab



Mitosis Lab

1. Explain how mitosis leads to daughter cells, each of which is diploid and generically identical to the original cell. What activities are going on in the cell during interphase?

The main goal of interphase is to prepare a cell for the rest of the cycle to divide. In order to prepare for division, the cell needs to grow and develop. The cell will copy the cell’s chromosomes to create two sets for each of the daughter cells. During interphase the cell will also being to grow the essential organelles and proteins needed to function including the mitochondria and endoplasmic reticulum.

2. How does mitosis differ in plant and animal cells? How does plant mitosis accommodate a rigid, inflexible cell wall?

Plant cells vary from animal cells by having a surrounding cell wall. During the entire mitosis process, the cell wall will always surround the cell. During telophase, the cell plate begins to form, which will then form a cell wall to create the two separate daughter cells. The creation of a cell wall forming between the daughter cells is different than the process of an animal cell. During telophase and cytokenesis the animal cell’s two daughter cells will split off by a pinching of the microfilaments.

3. What is the role of the centrosome (the area surrounding the centrioles)? Is it necessary for mitosis?

A centrosome is an important piece of mitosis because the centrosome begins the production of spindle microtubules during prophase. The spindles are used to connect two separating chromosomes. The chromosomes are separated from opposite ends of the cell because the spindles can hold the chromosomes in place and control the movement of chromosomes.

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1. If your observations had not been restricted to the area of the root tip that is actively dividing, how would your results have been different?

In plant cells, the root tip, or apical meristem, is the location for a division of cells because of the tissue found. If the experiment was found in a location that was higher than the root tip, like the maturation and elongation region, then the majority of the cells found there would be in interphase where the cells can found the cell’s function and properly form. The division of cells in a plant cell, is only found in the root tip because once the tissue is not in the region, the cells have matured and will begin to function.

2. What can you infer about the relative length of time an onion root tip cell spends in each stage of cell division?

Onion root tip cells spend the majority of time in interphase. The data suggests that the cell will spend 86% of the time in interphase. Interphase is an important phase of the cell because that is where the cell grows and prepares for division. Also once the cell is finished division the cell will be in interphase because that is where the organelles are formed and the cell has the ability to function. Prophase is the second longest stage, 11%, because that is where the sister chromatids are joined together. Metaphase, anaphase and telophase only last between .7-1.4% because the phases are fast and focus on the movement of the chromosomes and the division of the cells.

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Chromatography comes from the Greek roots “chroma” meaning color and “tography” meaning graph or writing. Molecularly though, chromatography separate molecules. In AP Biology, students went outside to collect a variety of leaves and then created a chromatogram for each leaf and calculated the Rf values for the pigments. Chromatography can happen by three different reason: solubility, adhesion, and mass of solvent. In order to observe chromatography, chromatography paper is used to allow adhesion of the solute to the paper. The solvent, acetone in the experiment, allows the solute to dissolve

in the solvent. In order to gain data from the experiment the Rf value is found which is the distance of pigment divided by the distance of the solvent. This information is important because if pigments have the same Rf value, then the pigments are the same because Rf is a constant. D-unknown is, on the chromatography paper, the value of the pigment whereas D- solvent is, on the chromatography paper, the movement of the solvent. When observing the chromatogram, green leaves produced 2-3 pigments while non-green leaves, like red, only had 1-2 pigments.

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Green Pigments Red Pigment

By conducting the experiment, a person can observe how some pigments can move further than other pigments. The type of leaf, including the environment, color, texture and structure can vary the results of the types of pigments. Since there are so many different types of pigments, how do each pigment affect plants? If the pigments affect positively, why have no all plants mimicked more thriving plants’ pigments?

The Effects of Low pH on the Rate of Catalase Catalyzed Reactions

The purpose of the lab is to view how catalase reaction rates change by increasing or decreasing with different levels of pH.

In cells there are proteins that are enzymes. Enzymes function like a catalyst. Catalysts are important because catalysts lower the activation energy required for molecules to react with other molecules. Since it requires less energy, the chemical reactions are quicker. A type of enzyme used in the experiment is a catalase. A catalase releases energy and breaks down the substrate H2O2 into H20 and O2. Catalase is found in humans, animals and plants , and tends to work best with a pH of 7, or neutral, and a temperature that the inner body has, or 37 degrees Celsius.

If the rate of the catalyzed reaction is effected by a low pH, then the catalase with a more acidic pH will have a decreased catalyzed reaction.

The constants include temperature, concentration of the substrate H2O2, concentration of the enzyme catalase, amount of water, and no inhibitors present.


1. Fill a beaker with water

2. Take one graduated tube with an open end and place in the beaker

3. Take a sealed end graduated tube and fill with 10mL of H202 and add 350 Meu Liters of H20
4. Place 100 Meu Liters of the catalase in the same graduated tube
5. Connect a long tube to both lids of the graduated tubes and seal with a binder clip
6. Remove the binder clip and quickly begin timing
7. Every 10 seconds record the level of the water in the graduated tube to observe how much the water dropped


Schmitz, Madison. Lab Setup. 2013. Photograph. Belmont.photo-4

Graph Title: The Rate of the Oxygen Produced Per 10 Seconds


The enzyme with a pH of 2.5 had a constant rate of 0mL of Oxygen produced per 10 seconds.
The enzyme with a pH of 3.4 remained at a constant rate of 0mL of Oxygen produced per 10 seconds until 80 seconds. At 80 seconds, there was a rate of .25mL of Oxygen produced per 10 seconds.

Addition to Conclusion: The lab tested how different pHs affect the rate of Oxygen produced over time for a catalyzed reaction. Three different pHs were used including a pH of 2.5, 3.4 and 4.7. The pH of 2.5 had a constant rate of 0mL of oxygen produced for 100 second. The pH of 3.4 had a rate of .25mL of oxygen produced for every 100 seconds. The pH of 4.7 had a rate of 3.5 mL of oxygen produced for every 100 seconds. With the data collected, the hypothesis was supported that with a lower pH value, then the rate of reaction would decrease.
In the lab, the enzyme with a pH of 2.5 was too far out of optimal range. This means that with a pH that is too high or too low, the rate of oxygen produced per time will be denatured and cannot produce a normal rate of reaction.

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