Kingdom Protista

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Mitosis Lab


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

Mitosis leads to two diploid daughter cells that are identical because the genetic information is copied identically and replicated. Then the cell is split in half leaving two daughter cells with identical genetic material. During Interphase, the cell is at its “resting phase.” However, the cell is not actually resting. The cell is doing its normal tasks and it is also replicating its genetic material so it can be ready to go through mitosis.

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

Mitosis in plant cells and animal cells differ because plant cells do not have centrioles. Plant cells also can not pinch their cell walls so instead the cells build a cell plate through the middle to separate the two cells.

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

The role of the centrosome is that it pulls the spindle fibers to this location so the centrioles are at opposite cells. This is necessary for mitosis because if the spindle fibers were’t pulled to opposite cells, then the chromosomes would not be able to be pulled apart. If the chromosomes were not pulled apart, then the cell would be unable to perform mitosis.

#of cells 1     #of cells 2     #of cells 3     Total    %of total cells   Time in stage

Interphase         282                   211                 198             691               86%              1238.4 min

Prophase            29                     32                    21                82               10.1%          145.44 min

Metaphase          9                        6                      5                 20               2.5%             36 min

Anaphase            2                        1                       4                  7                .9%               12.96 min

Telophase           1                        1                       2                  4                .5%                7.2 min

total cells counted- 804

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?

If the observations were not limited to the restricted area of the root tip, then there would be only cells in the interphase because none of the cells would be actively dividing. There would have been no cells from Prophase, Metaphase, Anaphase, or Telophase.

Based on the data in the images-8table, what can you infer about the relative length of time anonion root tip cell spends in each stage of cell division?

Based on the data, the onion root tip cells spend most of their time during the “rest cycle” or interphase. The term rest cycle refers to the fact that they are not starting to split at that time. They are not really at rest.





The basic importance of chromatography is to separate molecules. This is important because chromatography allows us to separate the different color pigments. The purpose of the paper is to draw the solution up the paper, while the purpose of the solvent is to move the different pigments up the paper. The factors that allow chromatography to happen is solubility, adhesion, and mass of the solute. The Rf value stands for distance of pigment over the distance of the solvent. The Rf value is useful to scientists because the value helps them identify substances and what they contain. D unknown is how far the pigments traveled. D solvent is how far the solvents have traveled. 0-1The green leaf had two bands of pigments, green and yellow. The red leaf had two bands of pigment, purple and orange. I learned that even though leafs appear to only be green, they contain many other colors such as yellow, red, and orange.  There are more pigments than the plant appears to have. A question I still have is: Why can’t human cells use photosynthesis


Title: The effect of pH on the rate of catalase reaction

Purpose: To determine if pH has an effect on enzymatic reaction, in particular on catalase.


Catalase is the enzyme that functions in cells. Catalase can be found in plant and animal cells. An enzyme is a catalyst that speeds up the reactions of chemical reactions. Catalysts are molecules that increase the speed of chemical reactions by decreasing the activation energy of a reaction. Catalase converts H2O2 into oxygen and water and is found in the livers of animals and humans. Catalase functions at an optimum pH of 7.0, neutral and operates naturally at a temperature of 37 degrees Celsius. A change in pH can affect the enzyme and cause the enzyme to become denatured. The balanced equation for this decomposition reaction is 2H2O–> 2H2O + O2


If the pH of the H2O2 and catalase solution is acidic, a pH lower than 7, then the rate of the reaction will be lower than when the pH is neutral.




  1. Fill a graduated tube with 10mL of H2Oand 350mL H2O in an upright position.
  2. Fill two beakers with 200mL of water.
  3. Put the graduated tube with the hole through the bottom in one of the tubes (upside down tube).
  4. Attach the end of the clear plastic pipe through the hole in the graduated tube in the water.
  5. Attach the opposite end of the pipe to the lid of the other graduated tube containing H2O2 (right side up tube).
  6. Place two binder clips on the pipe, each clip has an equal distance between the tube and the middle of the entire pipe. (Shown above).
  7. Add the acid (lemon juice) to the H2O2.
  8. Add the Catalase to the H2Osolution then immediately remove the binder clips and begin the timer.
  9. Hold the graduated tube steadily in the water and in such a way that the measurements can be read legibly. Do not move the tube.
  10. Record the time as soon as the water level increases or decreases a mL mark on the tube; written in time increments of 10′s, 20′s, and 100′s. (Shown below).
  11. Clean and rise all equipment before repeating steps 1-9 for two remaining trials.




Analysis: When the pH of the solution was more acidic, the water dropped at a slower rate. The water dropping is because of the rise in oxygen level. The lowest pH level was so acidic, that there was no reaction. The pH of 2.5 , the most had the slowest reaction rate,  and the pH of 4.7 had the fastest reaction rate.


The data reveals that  pH affects the rate of catalase reactions. The data shows that the solution of lemon juice and hydrogen peroxide with a pH of 3.4 produced more oxygen gas when catalase was added than the lemon juice with a pH of 2.5 when catalase was added. At 100 seconds, the solution with a pH of 2.5 had 0mL of oxygen released, the solution with a pH of 3.4 had .25mL of oxygen released, and the 3.48mL released. The baseline we used was the solution with the pH of 4.7 because that was the pH closest to the neutral 7. The hypothesis is supported by the data . The amount of oxygen gas produced shows the rate that hydrogen peroxide is broken down into oxygen gas and water. Due to the fact that the hydrogen peroxide with a pH of 4.7 produced the greatest amount of oxygen gas when catalase was added, the reaction occurred at the fastest rate out of all of the other tested pHs. The lemon juice with the pH of 2.5 produced no gas. This shows the when a more acidic solution is added, the rate of reaction will decrease. The pH affects the rate of reaction because when the solution is too acidic, the catalase is unable to break down the hydrogen peroxide (H2O2). If the hydrogen peroxide is unable to be broken down, no reaction will appear to be happening in the experiment as shown by the solution with the pH of 2.5. In the data table of the pH with 4.7 and 3.4, there was errors with the time keeping and measuring so there is no data reported for certain times.

I hope you learned something about the effect pH has on the rate of the enzyme catalase. Remember KEEP CALM AND LEARN ON.

2 Responses to Investigations

  1. serenagh says:

    Great lab! Love all the pictures, colors and diagrams. Great use of technology, Carly! I remember having fun working on labs with you, this semester.

  2. Hannah R says:

    You have a lot of pictures which makes everything so much easier to understand.

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