UMUC Biology 102 / 103 Lab 3: Cell Structure And Function ANSWER KEY

This contains 100% correct material for UMUC Biology 103 LAB03. However, this is an Answer Key, which means, you should put it in your own words. Here is a sample for the Pre lab questions answered:

Pre-Lab Questions

1. Identify the major similarities and differences between prokaryotic and eukaryotic cells. (2 pts)

Prokaryotes tend to be less complex than eukaryotic cells, with fewer organelles and (generally) fewer requirements for survival. Eukaryotes have a nucleus, while prokaryotes do not. Both eukaryotes and prokaryotes have DNA, a cell membrane, and cytoplasm.

2. Where is the DNA housed in a prokaryotic cell? Where is it housed in a eukaryotic cell? (2 pts)

DNA is housed in the nucleus in eukaryotic cells. Prokaryotic cells do not have a nucleus, and thus DNA exists freely in the cytoplasm.

3. Identify three structures which provide support and protection in a eukaryotic cell. (2 pts)

The cell membrane, the cytoplasm, and the cytoskeleton (microtubules, microfilaments, etc.).

The rest of the questions are answered as well:

Onion Root Tip 100X g (Small)

Experiment 1: Cell Structure and Function

Post-Lab Questions

1. Label each of the arrows in the following slide image:

2. What is the difference between the rough and smooth endoplasmic reticulum?

3. Would an animal cell be able to survive without a mitochondria? Why or why not?

4. What could you determine about a specimen if you observed a slide image showing the specimen with a cell wall, but no nucleus or mitochondria?

5. Hypothesize why parts of a plant, such as the leaves, are green, but other parts, such as the roots, are not. Use scientific reasoning to support your hypothesis.

Experiment 2: Osmosis - Direction and Concentration Gradients

Data Tables and Post-Lab Assessment

Table 3: Sucrose Concentration vs. Tubing Permeability

Band Color

Sucrose %

Initial Volume (mL)

Final Volume (mL)

Net Displacement (mL)

Yellow

Red

Blue

Green

Hypothesis:

Post-Lab Questions

1. For each of the tubing pieces, identify whether the solution inside was hypotonic, hypertonic, or isotonic in comparison to the beaker solution in which it was placed.

2. Which tubing increased the most in volume? Explain why this happened.

3. What do the results of this experiment this tell you about the relative tonicity between the contents of the tubing and the solution in the beaker?

4. What would happen if the tubing with the yellow band was placed in a beaker of distilled water?

5. How are excess salts that accumulate in cells transferred to the blood stream so they can be removed from the body? Be sure to explain how this process works in terms of tonicity.

6. If you wanted water to flow out of a tubing piece filled with a 50% solution, what would the minimum concentration of the beaker solution need to be? Explain your answer using scientific evidence.

7. How is this experiment similar to the way a cell membrane works in the body? How is it different? Be specific with your response.