Shortly after the discovery of kinetin, it was observed that the differentiation of cultured callus tissue derived from tobacco pith segments into either roots or shoots depends on the ratio of auxin to cytokinin in the culture medium. Whereas

a) high auxin:cytokinin ratios stimulated the formation of roots

b) high auxin:cytokinin ratios stimulated the formation of shoots

c) low auxin:cytokinin ratios led to the formation of shoots

d) low auxin:cytokinin ratios stimulated the formation of roots

which of the following combination is correct about the ratio of auxin to cytokinin

TLS Online TPP Program

#Question id: 30106

#Unit 1. Molecules and their Interaction Relevant to Biology

If a cell has an adequate supply of adenine nucleotides but requires more guanine nucleotides for protein synthesis:

1. Glutamine-PRPP amidotransferase will not be fully inhibited.

2. AMP will be a feedback inhibitor of the condensation of IMP with aspartate.

3. ATP will stimulate the production of GMP from IMP.

4. ATP will inhibit nucleoside diphosphate reductase.

TLS Online TPP Program

#Question id: 30107

#Unit 1. Molecules and their Interaction Relevant to Biology

Major controls of de novo AMP synthesis include:

1. allosteric inhibition by GMP.

2. allosteric inhibition by AMP.

3. availability of PRPP.

4. stimulation by GTP.

TLS Online TPP Program

#Question id: 30108

#Unit 1. Molecules and their Interaction Relevant to Biology

Aspartate plays a role in all of the following EXCEPT:

TLS Online TPP Program

#Question id: 30109

#Unit 1. Molecules and their Interaction Relevant to Biology

Allopurinol is an inhibitor of xanthine oxidase. Administration of allopurinol to a patient with gout and normal HG-PRT levels would be expected to lead to all of the following EXCEPT:

TLS Online TPP Program

#Question id: 30110

#Unit 1. Molecules and their Interaction Relevant to Biology

The ribose phosphate group of purine nucleotide is taken from which compound?

TLS Online TPP Program

#Question id: 30111

#Unit 1. Molecules and their Interaction Relevant to Biology

What is the source of the C-2 during the de novo biosynthesis of pyrimidines?