Correct Option
The correct option is Adenine.
Explanation
Kinetin belongs to the group of plant growth regulators known as cytokinins. These hormones are primarily responsible for promoting cell division (cytokinesis) and delaying senescence in plants. Chemically, most cytokinins are derivatives of purine nitrogenous bases.
Analysis
Kinetin is chemically identified as N6-furfurylamino purine. It is a modified form of Adenine, a purine base found in nucleic acids (DNA and RNA).
- Adenine (Option a): Kinetin was originally discovered by Miller et al. (1955) from autoclaved herring sperm DNA. The heat treatment resulted in the modification of the adenine moiety within the DNA to form kinetin.
- Guanine (Option b): Although Guanine is also a purine base, kinetin is not derived from it.
- Thymine and Uracil (Options c and d): These are pyrimidine bases. Cytokinins like kinetin possess a purine ring structure, making them structurally distinct from pyrimidines.
Key Takeaway
Kinetin is a cytokinin chemically derived from the purine base Adenine.