Hydrangea plants of the same genotype are planted in a large flower garden. Some of the plants produce blue flowers and others pink flowers. This can be best explained by which of the following?

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#Question id: 12409

#Unit 6. System Physiology – Plant

The Chemical Structure of ABA Determines Its Physiological Activity, 15 carbon compound 

a) The orientation of the carboxyl group at carbon 2 determines the cis and trans isomers of ABA. Nearly all the naturally occurring ABA is in the cis form

b) S enantiomer is the natural form; commercially available synthetic  ABA is a mixture of approximately equal amounts of the S and R forms.

c) The S enantiomer is the only one that is active in fast responses to ABA, such as stomatal closure

d) In long-term responses, such as seed maturation, only R-enantiomers are active

e) In contrast to the cis and trans isomers, the S and R forms cannot be interconverted in the plant tissue

Which of the following is the correct prediction about the active form  of ABA?

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#Question id: 12407

#Unit 6. System Physiology – Plant

ABA is synthesized via _____A________, the biosynthetic processes  occur in_____B_____and ____C_____.

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#Question id: 12404

#Unit 6. System Physiology – Plant

Covalent conjugation of amino acids to IAA can result in___

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#Question id: 12401

#Unit 6. System Physiology – Plant

IAA enters the cell either passively in the undissociated form (IAAH) or by transporter in the anionic form (IAA-) , which one of the following  transporter are involved in influx of the anionic form of auxin?

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#Question id: 12400

#Unit 6. System Physiology – Plant

Given  some  statements  about auxin  signal  transduction  pathway;

a) ARFs bind the AuxRE stably, must form dimers promote transcription by binding to two AuxREs arranged in a palindrome

b) inactive heterodimers may act to inhibit ARF–AuxRE binding, thereby blocking either gene activation or repression

c) Protein encodes the AUX/IAA gene family can inhibit the transcription of early auxin response genes by forming inactive heterodimers with ARFs

d) Auxin induces the transcription of the early response genes by promoting the proteolytic degradation of the inhibitory AUX/IAA proteins so that active ARF dimers can form

e) AUX/IAA turnover to involve ubiquitination by a ubiquitin ligase and proteolysis by the massive 26S proteasome complex

f) A negative feedback loop is introduced into the pathway by virtue of the fact that one of the gene families turned on by auxin is AUX/IAA, which inhibits the response.

Find out the correct sequence from the following above statements;

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#Question id: 12395

#Unit 6. System Physiology – Plant

In theory, auxin could increase the rate of proton extrusion by two possible mechanisms:

I) H+-ATPase activation

II) H+-ATPase synthesis

a) Auxin involves in the activation of ATP-driven proton-pump (H+-ATPase) indirectly

b) ABPs appear to be able to activate the plasma membrane H+-ATPase in the presence of auxin

c) Activity of the H+- ATPase is repressed by the C-terminal domain of the enzyme, which can block the catalytic site  in absence of auxin

d) The protein is synthesized on the rough endoplasmic reticulum and targeted via the secretory pathway to the plasma membrane

Find out the correct explanation of given mechanisms.