TLS Online TPP Program

#Question id: 18835


Polymerase chain reaction (PCR) utilizes a heat-stable polymerase (Taq polymerase) to amplify DNA strand. Which of the statement best describes why thermo-stable polymerases are required for PCR?

#Unit 13. Methods in Biology
  1. PCR needs thermal cycling, and the Taq polymerases can be inactivated since they are not needed during the low-temperature steps. 
  2. Heat stable (Taq) polymerase do not break the dsDNA unless the temperature is very high. Therefore a heat-stable (Taq) polymerase is required.
  3. PCR needs thermal cycling, and the heat-stable (Taq) polymerases will not denature to lose efficacy in DNA polymerization during the high temperature (95oC) step. 
  4. The interaction between divalent cations and DNA polymerase is much efficient during high-temperature steps. Thus PCR requires heat-stable DNA polymerase.
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TLS Online TPP Program

#Question id: 24524

#Unit 11. Evolution and Behavior

Which of the following is defined as any consistent difference in fitness among phenotypically different classes of biological entities?

TLS Online TPP Program

#Question id: 11902

#Unit 6. System Physiology – Plant

A chemiosmotic model  has been proposed  to explain Polar transport , following steps are involve in the transport of auxin polarly;

a) IAA enters the cell either passively in the undissociated form (IAAH) or by secondary active cotransport in the anionic form (IAA–)

b) The cell wall is maintained at an acidic pH by the activity of the plasma membrane H+- ATPase

c) In the cytosol, which has acidic pH, the IAAH form predominates

d) The anions exit the cell via auxin anion efflux carriers that are concentrated at the basal ends of each cell in the longitudinal pathway

Which of the following is the correct statements about the polarly transporting of auxin?

TLS Online TPP Program

#Question id: 2855

#Unit 2. Cellular Organization

Which statements are correct about lac operator;

I. The site bound by the Lac repressor.

II. The lac operator overlaps the promoter, and so the repressor bound to the operator physically prevents RNA polymerase from binding to the promoter and thus inhibit the RNA synthesis.

III. Have 21-bp sequence with twofold symmetric and is recognized by four subunits of Lac repressor, two binding to each half-site.

IV. CAP binds as a dimer to a site similar in length to that of the lac operator, but different in sequence. This site is located some 60 bp upstream of the start site of transcription.

TLS Online TPP Program

#Question id: 1044

#Unit 4. Cell Communication and Cell Signaling

Are all fungi detrimental (bad) for other organisms?

TLS Online TPP Program

#Question id: 28875

#Unit 4. Cell Communication and Cell Signaling

Wnt proteins are modified by linkage of__