Name: Date:

Scenario: A new food source was located on Mars for NASA scientist to use while on mission there. Pilot Jones is a vegan which means she does not eat any animal products. Can she eat the new food source?

Problem/Question:

Research: Review the last several assignments to help you prepare a hypothesis.

Hypothesis: Based on my own research, I think that this is a ______cell because

Experiment:

Microscope rules

  1. Always carry or move a microscope with two hands, one on the arm, and one on the bottom.
  2. Always use the lowest power lens (the shortest lens) when you take a slide on and off the stage.
  3. Always start with the lowest power lens (the shortest lens). Get the slide in focus there, first using the coarse focus knob (the large knob) to get it close, THEN using the fine focus knob (the small knob) to get it perfectly in focus. From there, you can switch to a higher power lens.
  4. Always look from the SIDE of the microscope, not through the eyepiece, when switching lenses to avoid hitting the lens on the slide.
  5. Only use the coarse focus knob (the large knob) when you are using the lowest power lens (the shortest lens). Using the coarse focus knob on a higher power can crack the lens!
  6. Please turn off the light and cover the microscope when you are finished.

Procedure:

  1. Cut out the letter “e” and place it on the slide face up.
  2. Add a drop of water to the slide.
  3. Place the cover slip on top of the “e” and drop of water at a 45-degree angle and lower. Draw what is on the slide in Figure 1.
  4. Place the slide on the stage and view in low power (4X). Center the “e” in your field of view. Draw what you see in Figure 2.
  5. Move the slide to the left, what happens? Move the slide to the right, what happens? Up? Down?
  1. View the specimen at 10X. Draw in Figure 3.
  2. Center the “e” in your field of view, and view at high power. Draw in Figure 4.

Write a short description of each of the following:

--cell membrane

--cytoplasm

--nucleus

--organelle

--eukaryote

Procedure:

  1. Put a drop of methylene blue on a slide. Caution: methylene blue will stain clothes and skin.
  2. Gently scrape the inside of your cheek with the flat side of a toothpick. Scrape lightly.
  3. Stir the end of the toothpick into the stain and throw the toothpick away.
  4. Place a coverslip onto the slide.
  5. Use the SCANNING objective to focus. You probably will not see the cells at this power.
  6. Switch to low power. Cells should be visible, but they will be small and look like nearly clear purplish blobs. If you are looking at something dark purple, it is probably not a cell.
  7. Once you think you have located a cell, switch to high power and refocus.

Results

---Sketch the cell at low and high power. Label the nucleus, cytoplasm, and cell membrane. Draw your cells to scale.

Scanning
/ Low
/ High

Analyze Your Results

  1. Why is methylene blue necessary?
  1. List 2 organelles that were NOT visible but should have been in the cheek cell.
  1. Compare with specimen from Mars. How are they similar? How are they different?
  1. Is the cheek cell a eukaryote or prokaryote? How do you know?

Onion skin cells

  1. Add 2 drops of iodine to the center of a glass slide. Be careful! Iodine can stain your clothes.
  2. Take a small piece of onion. Use tweezers to peel off the skin from the underside (the rough, white side) of the onion. Throw the rest of the onion piece away.
  3. Carefully lay the onion skin flat in the center of the slide on top of the iodine.
  4. Add 2 drops of iodine to the top of the onion skin.
  5. Stand a thin glass cover slip on its edge near the onion skin, next to the drop of iodine.
  6. Slowly lower the other side of the cover slip until it covers the onion skin completely. If there are air bubbles, gently tap on the glass to “chase” them out.
  7. Make sure the lowest power lens (the shortest lens) is in place over the stage and the microscope light is turned on. Place the slide onto the stage of the microscope.
  8. Look through the eyepiece and turn the coarse focus knob (the largest knob) until an image comes into focus. It should look like a brick wall or like lizard skin.

Results

  1. Draw and describe the image at 4X. Label recognizable organelles.
  1. Draw and describe the image at 10X. Label recognizable organelles.
  2. Draw and describe the image at 40X. Label recognizable organelles.

Analyze Results

  1. Compare and contrast the cheek and onion cells.
  1. Compare the onion cell with the Mars specimen. Any similarities? Differences?

Conclusion

Based on my results, I can conclude that the organism is of a ______origin. To support this conclusion, I found