UMUC Biology 102/103 Lab 3: Cell Structure and Function

25 Jun UMUC Biology 102/103 Lab 3: Cell Structure and Function

Question
Your Full Name:

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:
Smith_Lab3).

You should submit your document as a Word (.doc or .docx) file to the assignment folder
for best compatibility.

Post a copy of the lab in Turnitin.com. There will be a 10 point deduction if this is not

LastName_Lab3 (e.g.,

done.

If a photo is missing, there is a 10 point deduction.

Include a photo of the lab. Each photo must include a piece of paper with the student’s
name and date the photo was taken.
Each question is worth 5 points.
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The table is worth 10 points.

Pre-Lab Questions
1. Identify at least 3 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?
a. prokaryotic cell –
b. eukaryotic cell –

3. Identify 3 structures which provide support and protection in a eukaryotic cell AND state what their job
is.
a. Structure 1
b. Structure 2
c. Structure 3

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Experiment 1: Cell Structure and Function
Post-Lab Questions
1. Label each of the arrows in the following slide image:

A

C
D

Onion Root Tip: 1000X

B
2. What is the difference between the rough and smooth endoplasmic reticulum? Discuss structure AND
function.
a. Rough ER b. Smooth ER –

3. Would a plant cell be able to survive without a mitochondria? Why or why not?
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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 roots, are NOT green, but other parts, such as the
leaves, are green. Use scientific reasoning to support your hypothesis.

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Experiment 2: Osmosis – Direction and Concentration Gradients
Data Tables and Post-Lab Assessment
Table 3: Sucrose Concentration vs. Tubing Permeability

%Sucrose
Initial
Net
Bag
Predict:
Final
Result:
%Sucrose outside
Volume
Displacement
Band
Water In,
Volume
Water In, Out,
in bag
bag (in
(mL)
(mL)
Color
Out, Both?
(mL)
Both?
beaker)
30%
3%
Yellow
Bag 1
Beaker A Beaker 2
15%
3%
Red
Bag 2
Beaker B Beaker 2
3%
3%
Blue
Bag 3
Beaker C Beaker 2
3%
30%
Green
Bag 4
Beaker A Beaker 1
Take a picture of your results. Include a note with your name and date on a piece
of paper and include it in the picture. Insert picture here:

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Hypothesis:

Post-Lab Questions
1. If the net displacement for one of the bags was .1 ml, would you consider the solution to be
hypertonic/hypotonic (depending on the direction of water flow) or isotonic? Please explain why.

2. Were your predictions consistent with your results? Please explain why or why not and note any
possible sources of error that may have had an impact on the results. Discuss each bag that had a
difference in prediction and result.

3. 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 and note which way water was
flowing – into the bag, out of the bag or both.

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Hypo/Hyper/Iso

In/Out/Both

a. yellow bag 1 –

b. red bag 2 –

c. blue bag 3 –

d. green bag 4 –

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

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5. What do the results of this experiment tell you about the relative tonicity between the contents of the
tubing in question 2 and the solution in the beaker?

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6. What would happen if the tubing with the yellow band (bag 1) was placed in a beaker of distilled
water? Explain why this would happen.

7. A. How are excess salts that accumulate in cells transferred to the blood stream so they can be
removed from the body? Research the answer and be sure to explain how this process works in
terms of tonicity. The name of the process is composed of 2 words: _______ _______

B. Explain how this process is different than the one used to transfer water back and forth across
cell membranes.

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8. If you wanted water to flow out of a tubing piece filled with a 70% solution, what would the minimum
concentration of the beaker solution need to be? Explain your answer using scientific evidence from
your experiment.

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

a. similar –

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b.

different –

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