1.  Auxin acidifies cell walls by turning on proton pumps.  How does this acidification lead to phototropism?

a)      The acid causes water to rush out of the cell. This causes the cells to go limp and the shoot appears to bend.

b)      The acid activates enzymes that loosen the cell wall allowing the cell to lengthen when water enters.

c)      The acid attracts water which fills the cell to capacity, causing it to bend.

d)      The acid breaks down water molecules which compromises the integrity of the tonoplast.

e)      None of the above.

2. Guard cells cover the opening on the underside of a leaf known as a stoma.  Which of the following does not occur when the stoma is open (uncovered by guard cells)?

a)      the leaf gains water from the environment

            b)   the leaf loses water to the dry atmosphere

c)       the leaf loses O₂ to the environment

d)       the leaf gains CO₂ from the environment

e)       the leaf moves sugar from a source to a sink

3.  If the soil surrounding the root of a plant is dry:

a)      the plant will speed up the rate of transpiration

b)      the plant will wait to die since it can no longer extract water from the soil

c)      the root hairs will pump out protons in exchange for osmotically-active ions

d)      the plant will close its “root stomata” 

e)      the plant will guide all water through the apoplastic route

4.  Which of the following would aid the process of transpiration?

a)      gravity

b)      pouring rain

c)      arid soil

d)      hot sun

e)      hydrophobic interaction of H₂O and xylem

5.  Would sugar continue to be loaded into the phloem if the plant ran out of ATP and was unable to generate additional ATP?

a)      Yes-  ATP does not have anything to do with sugar movement.

b)      Yes- though water transport in the xylem would cease.

c)      No. Proton pumps needed to load the phloem would not be able to operate.

d)      No. Sugar moves through its membrane transport protein bound to ATP.

      e) There is not enough information supplied to reach a conclusion.

6.  Which of the following statements about tropic hormones has to be false?

a)      The target cells for a tropic hormone have to be found within another endocrine gland

b)      The target cells of a tropic hormone are found within the skin epithelia.

c)      A tropic hormone reaches it targets cells by traveling via the circulatory system

d)      A tropic hormone was released by an endocrine gland

e)      A tropic hormone’s release may be subject to a negative feedback loop

7.  All of the following conditions reverse the effects of the binding of a signaling molecule to its receptor except:

a)      G protein’s exchange of GDP for GTP

b)      Breakdown of all second messengers

c)      Inactivation of all enzymes activated by the binding of the signaling molecule

d)      Diffusion of the signaling molecule away from its receptor

e)      Dephosphorylation of all proteins in the phosphorylation cascade

8.  Which of the following type of cell-to-cell signaling would occur the fastest?

a)      Local signaling

b)      Endocrine signaling

c)      Autocrine signaling

d)      Paracrine signaling

e)      Signaling through gap junctions

9.  The receptor for hormone “Q” is located in the nucleus. Based on this information which of the following must be false?

a)      The hormone and its receptor function as a transcription factor.

b)      The hormone works in minute quantities

c)      The hormone and its receptor turn off genes

d)      The hormone generates second messengers

e)      The hormone is lipid soluble

10.  A  G -protein that is unable to hydrolyze its bound GTP:

a)      Stays in the active state

b)      Cannot get activated

c)      Cannot bind and activate enzymes

d)      Is functioning normally

e)      Turns off too quickly to pass along any message delivered by the binding of the signaling molecule

11.  Consider the diagram of decapitated shoots with agar blocks in the figure (above).  Which of the following numbers would best describe the degree of bending (off of vertical) of each of the shoots after an appropriate time period?

a)      Shoot A = 0°,  shoot B = 15°

b)      Shoot A = 15°, shoot B = 0°

c)      Shoot A = 15°, shoot B = 15°

d)      Shoot A = 60°, shoot B = 60°

e)      Neither would bend

12.  Which of the following helped you determine your answer to question number 11?

a)      The auxin redistribution hypothesis is incorrect.

b)      The auxin destruction hypothesis is incorrect.

c)      The auxin destruction hypothesis is correct.

d)      Auxin is made in response to sunlight.

e)      Auxin is not made in the dark.

Answers:  1) b,   2) a,   3) c,   4) d,   5) c,   6) b

                 7) a    8) e,   9) d,   10) a,   11) c    12) b