Correct option is C
Correct Answer: (3) A, C and D
Explanation – Cytokinin (CK) Biosynthesis in Plants:
Cytokinins are a class of plant hormones involved in cell division, shoot initiation, and many developmental processes. Let's analyze each statement:
A."Trans-zeatin (tZ) and iso-pentenyladenine (iP) are common active forms of isoprenoid CKs."
Correct
Trans-zeatin (tZ) and isopentenyladenine (iP) are bioactive isoprenoid cytokinins.
These are naturally occurring and biologically active, widely found in plants.
B."CKs are present as nucleoside and glycosidic conjugates but not as nucleotide conjugates."
Incorrect
Cytokinins exist in multiple forms:
Nucleotides (CK-ribonucleotides)
Nucleosides (CK-ribosides)
Free bases (active forms)
Glycosides (storage or inactivation forms)
So, saying "not as nucleotide conjugates" is incorrect — CKs are indeed found as nucleotide conjugates, especially in biosynthetic precursors.
C."Dephosphorylation and deribosylation steps are involved in two-step pathway for active CK formation."
Correct
In cytokinin activation, cytokinin nucleotides undergo:
Dephosphorylation
Deribosylation
To form active free-base CKs.
D."Lonely Guy (LOG) enzyme is involved in CK metabolism."
Correct
The LOG enzyme converts cytokinin nucleotides (inactive) into active free-base forms via phosphoribohydrolase activity.
LOG is essential in cytokinin activation and metabolism.
