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TLS Online TPP Program

#Question id: 7112

Although the vertebrate body plan outwardly displays a mirror-image symmetry with regard to left and right, the internal organs are not symmetrical. How does this left-right asymmetry develop?

#Unit 5. Developmental Biology
  1. The two cells of the Nieuwkoop center (at the 32-cell stage) signal each other and become either left or right.
  2. Maternal factors that determine left and right are packaged into the egg, just as dorsalizing factors are.
  3. Differential release of Ca2+ ions on the left side leads to expression of Nodal and Pitx2 on the left.
  4. Gravity determines the left-right axis: that side which is down becomes right and that side which is up becomes left.
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TLS Online TPP Program

#Question id: 12405

#Unit 6. System Physiology – Plant

Sequestration of auxin in endomembrane compartments, primarily in the__
TLS Online TPP Program

#Question id: 12406

#Unit 6. System Physiology – Plant

The β-oxidation of indole-3-butyric acid (IBA) to IAA takes place in___
TLS Online TPP Program

#Question id: 12407

#Unit 6. System Physiology – Plant

ABA is synthesized via _____A________, the biosynthetic processes  occur in_____B_____and ____C_____.
TLS Online TPP Program

#Question id: 12408

#Unit 6. System Physiology – Plant

Cleavage of the carotenoid by the enzyme NCED (9-cis-epoxycarotenoid dioxygenase) is a rate-limiting highly regulated step in ABA synthesis that produces the 15-carbon precursor molecule xanthoxin in
TLS Online TPP Program

#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?
TLS Online TPP Program

#Question id: 12410

#Unit 6. System Physiology – Plant

Precursor of the ABA is___