White-breasted nuthatches and Downy woodpeckers both eat insects that hide in the furrows of bark in hardwood trees. The Downy woodpecker searches for insects by hunting from the bottom of the tree trunk to the top, while the White-breasted nuthatch searches from the top of the trunk down. These hunting behaviours best illustrate which of the following ecological concepts?

TLS Online TPP Program

#Question id: 20332

#Unit 4. Cell Communication and Cell Signaling

What is LuxR and LuxI?

TLS Online TPP Program

#Question id: 20333

#Unit 4. Cell Communication and Cell Signaling

Choose true statements about Ax21-mediated quorum sensing;

a. It is a highly conserved sulfated peptide secreted by Xanthomonas oryzae.

b. Ax21 is sulfated by RaxST, which is a putative tyrosine sulfotransferase.

c. Sulfated Ax21 is secreted via the RaxABC type I secretion system

d. Sulfated Ax21 secreted is recognized by the rice XA21 receptor.

TLS Online TPP Program

#Question id: 20334

#Unit 4. Cell Communication and Cell Signaling

Sulfotransferases are the first enzymes of the core sulfation pathways, they transfer sulfate from PAPS to the hydroxyl or amino group of a wide variety of acceptors, as given below

a. Molecular basis of symbiotic host specificity in Rhizobium meliloti: nodH and nodPQ genes encode the sulfation of lipochito-oligosaccharide signals

b. Sulfation of the choriogonadotropin alpha subunit in human placental explants

c. Tyrosine sulfation of the amino terminus of CCR5 facilitates HIV-1 entry

d. A tyrosine-sulfated peptide based on the N terminus of CCR5 interacts with a CD4-enhanced epitope of the HIV-1 gp120 envelope glycoprotein and inhibits HIV-1 entry.

e. The Xanthomonas oryzae pv. oryzae raxP and raxQ genes encode an ATP sulfurylase and APS kinase that are required for AvrXa21 avirulence.

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

TLS Online TPP Program

#Question id: 20335

#Unit 4. Cell Communication and Cell Signaling

Quorum sensing-mediates the social cooperation and conflict both-

TLS Online TPP Program

#Question id: 7154

#Unit 4. Cell Communication and Cell Signaling

Cancer is believed to often arise from stem cells, rather than fully differentiated cells. Which of the following are consistent with this view?

TLS Online TPP Program

#Question id: 24202

#Unit 4. Cell Communication and Cell Signaling

Homophilic Binding appears: