Biology

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UMUC Biology 102/103

Lab 3: Cell Structure and Function

INSTRUCTIONS:

· On your own and without assistance, complete this Lab 3 Answer Sheet electronically and submit it via the Assignments Folder by the date listed in the Course Schedule (under Syllabus).

· To conduct your laboratory exercises, use the Laboratory Manual located under Course Content. Read the introduction and the directions for each exercise/experiment carefully before completing the exercises/experiments and answering the questions.

· Save your Lab 3 Answer Sheet in the following format: LastName_Lab3 (e.g., Smith_Lab3).

· You should submit your document as a Word (.doc or .docx) or Rich Text Format (.rtf) file for best compatibility.

Pre-Lab Questions

1. Identify the major similarities and differences between prokaryotic and eukaryotic cells.

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

3. Identify three structures which provide support and protection in a eukaryotic cell.

Onion Root Tip 100X g (Small) Experiment 1: Cell Structure and Function

Onion Root Tip: 1000X

A

B

C

D

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:

Take a picture of your results. Include a note with your name and date on an index card in the picture. Insert picture here:

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.

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