Question

Identify the correct pair of statements.
(I) Lutein is an oxygenated hydrocarbon.
(II) Inhibition of bacteroid respiration by oxygen is referred to as 'Warburg effect'.
(III) Triplet code 'UAA' is called 'Amber'.
(IV) Delay of senescence by cytokinins is known as 'Richmond-Lang effect'.

• A. (II), (III)
• B. (I), (IV)
• C. (I), (III)
• D. (II), (IV)

Answer 1

The correct option is D (II), (IV)

The statement I is incorrect as Lutein is deoxygenated hydrocarbon as it is a carotene.
Warburg and his colleagues showed an inhibitory effect of oxygen on photosynthesis since oxygen serves as the competitive inhibitor of carbon dioxide during carbon fixation and there is the simultaneous stimulatory effect of oxygen on photorespiration; the whole phenomenon is also known as the Warburg effect which makes statement II correct.
Statement III is incorrect as UAA (Ochre) and UAG (Amber) are among the three stop codons that cause termination of protein synthesis and does not code for any amino acid.
Statement IV is correct as Richmond-Lang effect refers to delay of senescence in leaves and other plant parts as a result of regulation of protein synthesis and nutrient mobilization by cytokinins.
Statement II and IV are correct.