Monday, October 13, 2008

First Unit Test (Friday, October 10th)

Well, we have made it through the first unit test, which was rather difficult. Here are some more of the questions and their answers from the test, to help with the corrections. Try to get the test corrections in on Thursday (although they aren't officially due until Friday).

Questions from Unit 1 Test:
1. Why does ice float in liquid water?
a) The liquid water molecules have more kinetic energy and thus support ice.
b) The ionic bonds between the molecules in ice prevent the ice from sinking.
c) Ice always has air bubbles that keep it afloat.
d) Hydrogen bonds stabilize and keep the molecules of ice farther apart than the water molecules of liquid water.
e) The crystalline lattice of ice causes it to be denser than liquid water.

2. Buffers are substances that help resist shifts in pH by

a) releasing H+ in acidic solutions.
b) Donating H+ to a solution when they have been depleted.
c) Releasing OH- in basic solutions.
d) Accepting H+ when they are in excess.
e) Both B and D.

3. Plasmodesmata in plant cells are most similar in function to which of the following structure in animal cells?
a) Peroxisomes
b) Desmosomes
c) Gap Junctions
d) Extracellular Matrix
e) Tight Junctions

4. According to the fluid mosaic model of cell membranes, which of the following is a true statement about membrane phospholipids?
a) They can move laterally along the plane of the membrane.
b) They frequently flip-flop from one side of the membrane to the other.
c) They occur in an uninterrupted bilayer, with membrane proteins restricted to the surface of the membrane
d) They are free to depart from the membrane and dissolve in the surrounding solution.
e) They have hydrophilic tails int he interior of the membrane

5. The surface of an integral membrane protein would be best described as

a) Hydrophilic.
b) Hydrophobic.
c) Amphipathic.
d) Completely covered with phospholipids.
e) Exposed on only one surface of the membrane.

6. Which of the following is a correct statement about sugar movement in phloem?
a) Diffusion can account for the observed rates of transport.
b) Movement can occur both upward and downward in the transport.
c) Sugar is translocated from sinks to sources.
d) Only phloem cells with nuclei can perform sugar movement.
e) Sugar transport does not require energy.

7. Arrange the following five events in an order that explains the mass flow of material in the phloem.
1. Water diffuses into the sieve tubes.
2. Leaf cells produce sugar by photosynthesis.
3. Solutes are actively transported into sieve tubes.
4. Sugar in transported from cell to cell in the leaf.
5. Sugar moves down the stem

a) 2, 1, 4, 3, 5
b) 1, 2, 3, 4, 5
c) 2, 4, 3, 1, 5
d) 4, 2, 1, 3, 5
e) 2, 4, 1, 3, 5

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