BICD 120 Midterm 2 Review Session

A high ABA/GA ratio in the seed promotes germination

• True

• False

Which of these is FALSE about GA and ABA synthesis?

• GA13ox is the enzyme involved in the branching step of GA synthesis

• Conversion of violaxanthin in the ABA synthesis pathway is stress-induced

• ABA aldehyde oxidase (AAO) inactivates bioactive ABA

• GA and ABA conjugation is reversible

What is the enzyme that is released by the aleurone layer of the seed in order to break down the endosperm into sugars for the growing seedling?

• AUX1

• AS1

• WUS

• alpha-amylase

What domain(s) does the FMN chromophore covalently bind to when PHOT1 is exposed to blue light?

• LOV domains

• J-alpha helix

• phosphatase domain

• kinase domain

Which of these statements about the phototropic response is true?

• When exposed to blue light, more auxin accumulates on the side of the plant exposed to the light

• Auxin inhibits the H+ pump ATPase

• Auxin causes accumulation of H+ in the cytoplasm

• Expansins are activated at low pH and promote cell expansion

Which of these statements about the gravitropic response is FALSE?

• Statoliths are enzymes that act as gravity sensors

• Accumulation of statoliths triggers cytoplasmic alkalinization of root cap cells

• Cytosolic alkalinization triggers accumulation of PINs in the direction of the gravity vector

• Auxin accumulation inhibits cell elongation in the root

Auxin traveling from the RAM to the root-shoot junction is...

• Basipetal transport

• Acropetal transport

IAAH has a pKa of 4.75. Which of these statements is FALSE?

• IAAH can passively diffuse through the cell membrane

• IAA- requires the AUX1 transporter to move into the cell

• There is a higher proportion of IAA-/IAAH at pH 6 compared to pH 9

• Auxin influx is nonpolar while auxin efflux is polar

In the presence of auxin...

• AUX/IAA repressor is bound to ARF --> ARFs promote transcription of early auxin response genes

• AUX/IAA repressor is degraded --> ARFs promotes transcription of early auxin response gene

• AUX/IAA repressor is bound to ARF --> ARFs inhibit transcription of early auxin response genes

• AUX/IAA repressor is degraded --> ARFs inhibit transcription of early auxin response genes

Which of these is false about SCF-TIR1?

• It is an E3 ligase that degrades AUX/IAA repressor

• It is part of the auxin receptor complex

• The TIR1 subunit is what interacts with the AUX/IAA repressor

• It adds phosphate groups to AUX/IAA repressor to signal it for degradation by the proteasome