A single-stranded DNA molecule contains 40 nucleotides with equal amounts of A, C, G, and T. This DNA strand can combine with a complementary DNA strand to form a double-stranded DNA molecule. Which of the following double-stranded DNA molecules would denature at a lower temperature than the 40 base-pair double-stranded molecule described above?

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#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?

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#Question id: 12410

#Unit 6. System Physiology – Plant

Precursor of the ABA is___

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#Question id: 12411

#Unit 10. Ecological Principles

Plant population age pyramids

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#Question id: 12412

#Unit 10. Ecological Principles

In most mammalian populations the sex ratio

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#Question id: 12413

#Unit 10. Ecological Principles

Mortality rate is calculated as