Form and Function
Week 1 quiz
5 April 2021
Name
1. The solutions in the arms of a U-tube are separated at the bottom of the tube by a selectively
permeable membrane. The membrane is permeable to sodium chloride but not to glucose. Side
A is filled with a solution of 0.4 M glucose and 0.5 M sodium chloride (NaCl), and side B is filled
with a solution containing 0.8 M glucose and 0.4 M sodium chloride. Initially, the volume in both
arms is the same. n
If you examine side A after three days, you should find a __decrease_________ in the
concentration of NaCl and a _____decrease_______ in the water level.
2. Which of the following substances cannot pass directly through the phospholipid
bilayer? Choose all that apply by typing an “x” next to them.
_____ carbon dioxide
_____ oxygen
_____ water
_X___ charged particles called ions, like potassium (K+) and chloride (Cl-)
___X_ negatively charged amino acid molecules (the building blocks of proteins)
3. Osmosis can be thought of as a special case of ___diffussion_________.
4. Celery stalks that are immersed in freshwater for several hours become stiff. Similar stalks
left in a 0.15 M salt solution become limp. What can we say about freshwater and the salt
solution with respect to the celery cells?
The freshwater is hypotonic to the celery cell
The saltwater is hypertonic to celery cell
5. Under what circumstances does transport of a compound across a membrane require
energy?
The circumstances that transport of a compound across a membrane requires energy is called
Active Transport.
6a. Complete the equation for Fick’s Law by writing the appropriate terms/variable names
beside each of the lettered boxes.
A
______=
B
k x _____________
D
____________
x
C
______________
A: Flux
B: Area
C: diffusion distance
D: driving force
6b. When you breathe in, oxygen enters your lungs and
reaches the alveoli, where it diffuses across the lining of the
alveoli into the blood stream. Oxygen uptake is represented
by term A in the equation above.
Lung to small
pouch-like endings
called alveoli
Briefly explain what specific term/variable in the Fick’s
equation above determines whether oxygen will diffuse into
the blood from the lungs, and what conditions (with respect
to oxygen levels) must exist for diffusion to occur in the
appropriate direction.
The driving force is going to be affected because in order
for things to diffuse you need a concentration gradient.
6c. Long-term cigarette smoking can cause a buildup of tar on the inner lining of the lungs.
Briefly explain what specific term/variable in Fick’s equation would be affected by smoking, and
what effect this would have on oxygen uptake from the lungs.
The diffusion distance since there would be a buildup of plague in the alveoli, the flux is going to
decrease since it’s harder to get particles into the cell