In the stomachs of ruminants, such as cows, certain microbes digest cellulose, a material the cow cannot digest itself. This interaction between cows and microbes represents an example of

TLS Online TPP Program

#Question id: 14685

#Unit 4. Cell Communication and Cell Signaling

In dark-adapted rod cells, a high level of cGMP keeps cGMP-gated nonselective cation channels open, leading to hyperpolarization of the plasma membrane and neurotransmitter release. 

B - Light absorption generates activated rhodopsin, R*, which binds inactive, GDP-bound Gαt protein and mediates the exchange of GDP for GTP . 

C- The free Gαt∙GTP activates PDE by binding to its inhibitory γ subunits and dissociating them from the catalytic α and β subunits . Relieved of their inhibition, the α and β subunits of PDE hydrolyze GMP to cGMP . 

D- The resulting decrease in cytosolic cGMP leads to dissociation of cGMP from the cation channels in the plasma membrane and the closing of those channels . 

E- The membrane then becomes transiently hyperpolarized, and neurotransmitter release is reduced. 

TLS Online TPP Program

#Question id: 14686

#Unit 4. Cell Communication and Cell Signaling

This member of the AKAP family, designated mAKAP, anchors both PDE and the regulatory subunit  of PKA to the nuclear membrane, maintaining them in a negative feedback loop that provides close local control of the ATP level and PKA activity.

B- The basal level of PDE activity in the presence of hormone (resting state) keeps cAMP levels below those necessary for PKA activation. 

C- Activation of β-adrenergic receptors causes an increase in cAMP to a level in excess of that which can be degraded by PDE. 

D- The resulting binding of cAMP to the R subunits of PKA releases the active catalytic (C) subunits into the cytosol. Some C subunits enter the nucleus, where they phosphorylate and thus activate certain transcription factors . Other C subunits phosphorylate PDE, stimulating its catalytic activity.

E-  Active PDE hydrolyzes cAMP, thereby driving cAMP levels back to basal levels and causing re-formation of the inactive PKA C-R complex. Subsequent de-phosphorylation of PDE returns the complex to the resting state.

TLS Online TPP Program

#Question id: 14687

#Unit 13. Methods in Biology

Find the probability of drawing one rupee coin from a purse with two compartments one of which contains 3 fifty paisa coins and 2 one-rupee coins and the other contains 2 fifty paisa coins and 3 one rupee coins.

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#Question id: 14688

#Unit 13. Methods in Biology

If A and B are two events such that  = 1/ 2 then the events A and B are

TLS Online TPP Program

#Question id: 14689

#Unit 13. Methods in Biology

A determinant is chosen at random from the set of all determinants of order 2 with elements 0 or 1 only. The probability that value of the determinant chosen is

positive is

TLS Online TPP Program

#Question id: 14690

#Unit 13. Methods in Biology

One hundred identical coins each with probability p of showing up heads are tossed. If 0 < p < 1 and the probability of heads showing on 50 coins is equal to that of the heads showing in 51 coins, then the value of p is