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TLS Online TPP Program

#Question id: 2884

When the temperature of a solution of DNA is raised to near the boiling point of water, the optical density, (called absorbance) at 260 nm markedly increases, a phenomenon known as hyperchromicity. Which of the following statement is INCORRECT from the given set of statements?

#Unit 2. Cellular Organization

  1. The explanation for this increase is that duplex DNA absorbs more ultraviolet light by ~40% than do individual DNA chains.

  2. This hyperchromicity is due to base stacking, which increases the capacity of the bases in duplex DNA to absorb ultraviolet light.

  3. The sharpness of the increase in absorbance at the melting temperature tells us that the denaturation and renaturation of complementary DNA strands is a highly cooperative, zippering-like process.

  4. At high ionic strength, the negative charges are shielded by cations, thereby destabilizing the helix. Conversely, at low ionic strength, the unshielded negative charges render the helix more stable.

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TLS Online TPP Program

#Question id: 10431

#Unit 6. System Physiology – Plant

The signal transduction pathways that lead to physiological or developmental responses, these responses fall into two general categories;
a) Ion fluxes, which cause relatively rapid turgor responses
b) the possible chain of events constituting the signal transduction pathways that bring about these effects
c) Altered gene expression, which typically results in longer-term responses
d) Gene expression altered shows short-term response
Which of the following combinations from above given general categories is true?
TLS Online TPP Program

#Question id: 10432

#Unit 6. System Physiology – Plant

Phytochrome interacting factors (PIFs) act as negative regulators of photomorphogenesis such as;
a) Most PIFs are constitutive activators of genes that are expressed in the dark or in response to shade
b) Most PIFs are constitutive repressor of genes that are expressed in the dark or in response to shade
c) In the light, Pfr promotes the degradation of the PIFs, blocking the transcription of skotomorphogenesis genes
d) In the light, Pfr promotes the activation of the PIFs, blocking the transcription of skotomorphogenesis genes
Which of the following combinations is correct about PIFs?
TLS Online TPP Program

#Question id: 10433

#Unit 6. System Physiology – Plant

Time course for inducing transcription. Kinetics of the induction of transcripts for a MYB-related transcription factor (MYB) and the light-harvesting chlorophyll a/b–binding protein (LHCB) in Arabidopsis, which of the following graph represents the correct relation between MYB and LHCB?
TLS Online TPP Program

#Question id: 10434

#Unit 6. System Physiology – Plant

Movement of the phytochrome into the nucleus takes place, which of the following is incorrect prediction about this movement?
TLS Online TPP Program

#Question id: 10435

#Unit 6. System Physiology – Plant

What happens when Pfr moves to the nucleus?
TLS Online TPP Program

#Question id: 10436

#Unit 6. System Physiology – Plant

Both PHYA and PHYB activate the transcription of LHCB gene for its expression, there following events occur during the activation of LHCB gene such as;

a) PhyA, both form is activated Pr and Pfr by phosphorylation Pr form move into the nucleus activate the light-regulated gene expression during degradation of  the HY5 by COP1

b) PhyA, Pfr form is activated by phosphorylation and move into the nucleus where it’s export the COP1 out of the nucleus, and activate the light-regulated gene expression

c) Phy B, activated phosphorylated Pfr form is move into the nucleus and binds to a dimer of the transcription factor PIF3, by inibiting PIF3 expression activate the transcription of LHCB gene by intermediate transcriptional factor MYB

d) Phy B, activated unphosphorylated Pfr form is move into the nucleus and binds to a monomer of the transcription factor PIF3, by inibiting PIF3 expression activate the transcription of MYB gene by intermediate transcriptional factor LHCB

Which of the following combination of the above statements of phytochrome forms is correct?