Name ______________________
Ch 5 quiz- Key
1. Describe the structure and function of enzymes. How do enzymes effect the energy of
activation (EA). (1)
Enzymes are proteins with a specific shape designed to catalyze reactions. Their structure
includes an active site where it binds to a substrate. Enzymes serve to lower the activation energy
of a reaction
2. Inhibitors interfere with enzyme activity. We discussed three types of inhibition is class.
Name 2 of the 3 types of inhibition and how they work. (1)
Inhibitors are
Competitive- these inhibitors reduce an enzymes productivity by blocking substrates
from entering the active site.
Noncompetitive- these inhibitors bind to the substrate in a place other than the active site,
and changes the shape of the enzyme so the substrate no longer fits into the active site
Feedback inhibition- this type of inhibition is when the product from the reaction acts as
an inhibitor.
3. Plasma membranes are selectively permeable. This means that……. (1)
Some molecules can pass through more easily than others
4. Diffusion does not require the cell to expend ATP. Therefore, diffusion is considered a
type of ….. (1)
A) exocytosis.
B) phagocytosis.
C) passive transport.
D) active transport.
E) endocytosis.
5. When would a cell need to use active transport? (1)
When transporting molecules that cannot diffuse or when moving against a concentration
gradient
6. There are three types of endosytosis that a cell uses. What type would a cell use to engage
in “cellular drinking”? (1)
pinocytosis
7. Membrane proteins serve a variety of functions. List 4 of those functions. (1)
Structure, cell-cell recognition, junctions, receptors, enzymes, signal transduction, transport
8. What is the difference between a coenzyme and a cofactor. (1)
Coenzymes are organic helpers for the enzyme. Cofactors are nonprotein helpers for the
enzyme
9. Daphnia are small, planktonic crustaceans that live in freshwater swamps, lakes and
ponds. If you were to remove a Daphnia from a pond and place it into the ocean, would the
Daphnia be in a solution that is hypertonic, hypotonic or isotonic? What would happen to the
Daphnia? Draw a picture showing the Daphnia in its ocean water environment and use
arrows to show the net movement of water molecules between the Daphnia and the ocean
water (2).
Hypertonic. The Daphnia would shrivel and die.
Water would move out of the Daphnia into the surrounding environment.