Bio 93 Midterm 1 Fall 2014
UCI Student ID: ____________________________
Use your scantron to mark your answers.
You may write on the exam booklet but you will be turning it in with the scantron.
There are 20 questions. Watch your time!
An organic chemistry lab uses “thin layer chromatography” to
determine the relative polarity of different molecules. The molecules
are added to the bottom of a glass plate covered with polar silicone
gel and the plate is placed in a beaker of ethyl acetate, a nonpolar
solvent. The solvent travels up the plate, carrying the molecules with
it. More polar molecules are attracted to the silicone and don’t travel
as far.
1. Molecules with which functional groups will be more attracted to the silicon gel on the plate?
A. Hydroxyl
B. Sulfhydryl
C. Methyl
2. Which is likely to be a nonpolar solvent?
A.
B.
Three pain medications (aspirin, caffeine, Anacin brand pain reliever)
were added to the starting line of the plate and the plate was placed in
the solvent. After the solvent was allowed to travel 5 cm up the plate,
the plate was removed and dried and the locations of the molecules
marked, as shown.
3. Which of the following is true?
A. Aspirin is more polar because it traveled further
B. Caffeine is more polar because it was more attracted to the
solvent
C. Aspirin is more polar because it was more attracted to the silicone
D. Caffeine is more polar because it did not travel as far
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Name: ___________________________
4. Which hypothesis is the most likely reason for this experiment?
A. Aspirin is a more effective pain reliever than caffeine or Anacin
B. Anacin is a combination of more than one pain reliever
C. Aspirin is a larger molecule than caffeine or Anacin
D. Ethyl acetate is more nonpolar than benzene
5. Which pain reliever is more likely to diffuse across plasma membranes in the brain?
A. Aspirin, because it is more polar
B. Caffeine, because it is more polar
C. Aspirin, because it is more nonpolar
D. Caffeine, because it is more nonpolar
6. This molecule is found in many plasma
membranes. What molecule is it most
similar to?
A. Phospholipid
B. Steroid
C. Protein
D. Cholesterol
In experiments called “fluorescence recovery after photobleaching” or FRAP, a fluorescent tag is added to the
polar head of a lipid. This makes the entire cell glow under fluorescent light. A laser is used to bleach (remove
color) from one small area of the membrane. The time required for lipids with non-bleached tags to diffuse into
the bleached area is then measured. A diagram is shown below.
7. Which membrane process is this experimental design best suited to measure?
A. Ability of membrane lipids to move laterally
B. Transport of polar molecules across the plasma membrane
C. Ability of cell to manufacture fluorescent tags
D. Ability of cell to manufacture membrane lipids
Bio 93 Midterm 1 Fall 2014
UCI Student ID: ____________________________
In an experiment to test the use of a new microscope in
FRAPping, researchers compared the recovery curve of a cell
with and without the addition of cyclodextrin (cdx), a drug
that affects membrane cholesterol. Here are their results:
8. Which treatment recovered its fluorescence faster, the
control or the cyclodextrin?
A. The control because it approached 100% fluorescence faster
B. The cyclodextrin because it approached 100% fluorescence faster
C. The control because the recovery curve is shifted to the right
D. The cyclodextrin because the recovery curve is shifted to the right.
9. What is the likely effect of cyclodextrin (assume 25oC)?
A. Decreases the amount of cholesterol, reducing membrane fluidity
B. Increases the amount of cholesterol, reducing membrane fluidity
C. Decreases the amount of cholesterol, increasing membrane fluidity
D. Increases the amount of cholesterol, increasing membrane fluidity
Researchers invited over 5,000 Americans to be part of a study that measured their reaction times – ability to
quickly press a button when an image appears on a computer screen. When they checked on the subjects 15
years later, they found that people with slower reaction times were more likely to have died.
10. If roughly 500 subjects were dead after 15 years, what percentage of the original group died?
A. 0.1%
B. 1%
C. 5%
D. 10%
11. The researchers listed the “hazard ratio” of slow-reaction-timers as 1.25, indicating their chance of dying was
1.25 times higher than those with normal reaction times. This is the same as:
A. A 0.25% increase
B. A 2.5% increase
C. A 25% increase
D. A 125% increase
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Name: ___________________________
This figure is from the article. The participants were divided into three groups: those with slowest reaction times,
those with medium reaction times, and those with fast reaction times.
12. What correlates with a slow reaction time?
A. Being male, not graduating high school
B. Drinking heavily, high poverty
C. Exercising little and being an ethnic minority
13. The breaking of an ionic bond:
A. Often occurs in the presence of water
B. Is a hydrolysis reaction
C. Dissociates a glucose molecule into carbons, hydrogens and oxygens
14. Which is true of actin but not microtubules?
A. Subunits added and subtracted from plus end
B. Minus ends are near the plasma membrane
C. Are associated with a motor protein
15. If microtubule subunits were unable to bind to each other, which would be affected?
A. Movement of cytoplasm and pseudopodia
B. Beating of cilia
C. Myosin pulling Z-disks toward each other
16. A drug suddenly blocks the sodium-potassium pumps in a cell membrane. This would cause:
A. An increase in ATP use
B. An increase in potassium ions entering the cell
C. The inside of the cell to become more negative
D. An increase in intracellular sodium
Bio 93 Midterm 1 Fall 2014
UCI Student ID: ____________________________
17. A common risk for runners new to marathons is drinking too much water. This causes hyponatremia, or low
sodium levels in the blood. Why would this cause headache, disorientation and sometimes death?
A. The cytoplasm in the brain cells has a lower water concentration
B. The blood is hypertonic to brain cells
C. Water would flow from the blood to the brain
D. Cells in the brain would attempt to pump sodium and potassium into the blood
18. Unlike simple diffusion, facilitated diffusion:
A. Moves charged molecules across the membrane
B. Does not require the use of a transporter
C. Moves substances from high to low concentration
D. Requires no energy
19. The figure at the right is an illustration of a “U-tube” apparatus. The membrane
(dashed line) separating both sides is permeable to water, but not permeable to the
solute particles shown. On the left side there are 21 particles in 5 mL of water and on
the right side there are 9 particles in 5 mL of water. After allowing the U-tube to come
to equilibrium, what do you expect to see?
A. There will be 15 particles on each side
B. There will be 7 ml of water on the left
C. There will be 6 ml of water on the right
D. The right side will remain hypertonic
20. What happens when you eat a Twinkie (a small cake)?
A. Molecules in the Twinkie are broken down by dehydration reactions that use water
B. Molecules in the Twinkie are broken down by hydrolysis reactions that use water
C. Molecules in the Twinkie are broken down by dehydration reactions that release water
D. Molecules in the Twinkie are broken down by hydrolysis reactions that release water
Your scantron must have your name, the key marked, your 8-digit student ID, and the correct bubbling of the ID:
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