Following statements are regarding to gap junctions.

i. Vertebrate gap junctions are composed of connexins, a family of structurally related transmembrane proteins with molecular weights between 26,000 and 60,000.

ii. Each vertebrate hexagonal particle consists of six noncovalently associated connexin molecules. Each individual connexin molecule has two membrane-spanning α helices with a topology similar to that of claudin.

iii. The permeability of gap junctions is regulated by posttranslational modification of connexins (e.g., phosphorylation) and is sensitive to changes in environmental conditions

such as intracellular pH and Ca2+ concentration, membrane potential, and the intercellular potential between adjacent interconnected cells (“voltage gating”).

iv. The assembly of connexins, their trafficking within cells, and the formation of functional gap junctions apparently depend on N-cadherin and its associated adapter proteins as well as desmosomal proteins.

Which of the following statements are correct?

TLS Online TPP Program

#Question id: 12200

#Unit 6. System Physiology – Plant

Given some observation of the auxin signalling pathway, which one of the following are the incorrect prediction about signalling?

TLS Online TPP Program

#Question id: 12199

#Unit 6. System Physiology – Plant

Some given statements about Auxin signalling pathways are listed;

a) The auxin receptor is composed of two proteins: the SCF complex component TIR1 and the repressor protein AUX/IAA

b) The binding of auxin to its receptor complex initiates ubiquitin-dependent degradation of the AUX/ IAA repressor protein by the 26S proteasome 

c) TIR1 recruits AUX/ IAA proteins to the SCFTIR1  complex in an auxin-independent manner

d) AUX/IAA proteins are ubiquitinated by the E3 ligase activity of the SCFTIR1 complex, which marks the protein for destruction by the 26S proteasome

Which of the following is correct explanation of Auxin signalling pathways?

TLS Online TPP Program

#Question id: 12198

#Unit 6. System Physiology – Plant

In theory, auxin could increase the rate of proton extrusion by some possible mechanisms such as:

a) Activation of pre-existing plasma membrane H+- ATPases

b) Synthesis of new H+-ATPases on the plasma membrane

c) Auxin-Induced Proton Extrusion May Involve Both Activation and Synthesis

TLS Online TPP Program

#Question id: 12197

#Unit 6. System Physiology – Plant

The following are certain facts regarding Auxin transport  in plants;

a) Auxin transport is polarly has been proposed through Chemiosmotic Model

b) Auxin translocation in the phloem is largely passive, not requiring energy directly

c) Polar transport requires energy and is gravity dependent

d) Auxin is transported nonpolarly in the Phloem

Which one of the following combination of the above statements is correct? 

TLS Online TPP Program

#Question id: 12196

#Unit 6. System Physiology – Plant

IAN pathway may be important in only few plant families:

TLS Online TPP Program

#Question id: 12195

#Unit 6. System Physiology – Plant

Which one of the following is function as endogenous regulators of polar auxin transport?