Biology 2107/03
Spring 2001
Second Examination
A.
Name
Matching. The answer to each question is ONE of the choices from the list.
Please write your choice in the blank provided. If more than one answer is listed,
the question will be counted as wrong. Please note that a choice may be used
more than once, or not at all. (2 pt each)
Matching List:
Active site
Amino Acid
Cellulose
Cholesterol
Chromatin
Cytoskeleton
Desmosomes
Diffusion
Disaccharide
Fatty acid chain
Gap junction
Golgi apparatus
Lysosomes
Matrix
Monosaccharide
Net diffusion
Nucleolus
Osmosis
Peroxisomes
Phospholipid
Polar head group
Rough endoplasmic reticulum
Secretory vesicles
Smooth endoplasmic reticulum
Stroma
Thylakoid Membrane
Tight junctions
Triglyceride
1. ______________________________This is a connection between two cells
through which cytoplasm can be exchanged directly between the cells.
2. ______________________________This is the polysaccharide found in plant cell
walls.
3. ______________________________This is a folded, sheet-like membranous
organelle to which ribosomes are attached.
4. ______________________________This is a connection between two cells in
which the connecting protein is attached to keratin fibers.
5. ______________________________This is a connection between two cells in
which the cells are linked by protein channels called connexons.
6. ______________________________These are membrane-enclosed packets of
protein and other materials that are expelled to the outside of the cell.
7. ______________________________These are membrane-enclosed packets
containing hydrolytic enzymes that digest large particles taken in by the cell.
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8. ______________________________These are membrane-enclosed packets
containing enzymes that help to eliminate the toxic products of oxygen
metabolism.
9. ______________________________This is the diffusion of water molecules
across a semipermeable membrane.
10. ______________________________Within the chloroplast, these membranes are
folded into stacks called grana.
11. ______________________________This term refers to the gel-like aqueous fluid
found inside the mitochondria.
12. ______________________________This is the best term in the list to describe
the movement of molecules from a region of high concentration to a region of low
concentration until an equilibrium is reached.
13. ______________________________This term refers to network of protein fibers
that extends through the cytoplasm of a cell, helping to regulate its shape and
movement.
14. ______________________________This is the gel-like, aqueous fluid found
inside the chloroplast.
15. ______________________________The function of this membrane is the
absorption of light energy in the process of photosynthesis.
16. ______________________________This is a dark-staining region inside the
nucleus. It is the site of ribosome synthesis.
17. ______________________________After proteins have been processed in the
endoplasmic reticulum, they are transported to this organelle where they are
further modified.
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The following diagram is used in questions 18 – 20.
18. ______________________________Which term in the list best describes the
overall structure (entire molecule) that is shown?
19. ______________________________Which term in the list best describes the part
labeled “A” in the diagram?
20. ______________________________Which term in the list best describes the part
labeled “B” in the diagram?
B.
Short answer and essay.
1.
Compare and contrast “simple diffusion across a membrane” and “facilitated
diffusion.” (10 pt)
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2.
Compare and contrast “facilitated diffusion” and “active transport.” (10 pt)
3.
How do phosphatidyl choline and phosphatidyl ethanolamine differ? You don’t
have to draw their structures or necessarily give molecular details, but you must
tell me specifically what parts of their structures differ. (2 pt)
4.
What is a liposome, how do you make it, and why does it form? In your answer,
you should use big words like “amphipathic.” (6 pt)
5.
The lipid bilayers of almost all biological membranes have compositional
asymmetry. What does this mean? (2 pt)
6.
Distinguish between “accuracy” and “precision.” (4 pt)
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7.
Briefly describe what a spectrophotometer does, what it is used for, and how it
works. (8 pt)
8.
Commercial laundry detergents often contain proteolytic enzymes that break
down protein stains (remember the television commercial in which “protein gets
out protein”). Imagine that you are working for a chemical company. You have
just isolated a new proteolytic enzyme from bacteria, and you need to know if it
will be useful as a detergent additive. You have an assay with which you can
measure the activity of the enzyme in a spectrophotometer (so don’t worry or go
off on a tangent about how you do this). What you need to know is:
(a) will the enzyme work best in the hot water, warm water, or cold water cycle of
a washing machine?
(b) will the enzyme work at the pH of a laundry detergent (different laundry
detergents have pHs between about 7.5 and 9.0?
(c) will the enzyme work in the presence of the detergent molecules (soap
molecules)?
Briefly describe how you would determine the answers to these questions. As
stated above, you may assume that you have a way to measure enzyme activity in
a spectrophotometer. (8 pt)
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9.
Compare and contrast “primary active transport” (that uses ATP as an energy
source) with “secondary active transport” (that uses an ion gradient as an energy
source). In you answer, you should use the absorption of glucose by intestinal
epithelial cells as an example. (10 pt)
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