E.coli has only 4.6 × 106 base pairs and completes the process of replication within 18 minutes; then the average rate of polymerisation is approximately:
In NCERT biology, the term kinetin was coined by F. Skoog and Miller. They introduced and named this cytokinin when studying plant growth regulators from extracts (e.g., coconut milk) in the 1950s.
🧠 Did You Know?
Went contributed to early work on plant growth regulation and auxins; Darwin’s studies are foundational in tropisms; Kurosawa is associated with research on cytokinins, but the term “kinetin” was coined by Skoog and Miller.
💡 NCERT Memory Line:
Kinetin term coined by Skoog and Miller (not by Went, Darwin, or Kurosawa).
Option 2 is incorrect. Glycine is an amino acid, not a lipid. NCERT classifies glycine as the simplest amino acid with a side chain of hydrogen. Lipids include fats, oils, and phospholipids like lecithin. Options 1, 3, and 4 are correct: sulfur is part of cysteine's thiol group; lecithin is a phospholipid containing phosphorus; tyrosine has an aromatic ring in its side chain.
🧠 Did You Know?
Some amino acids contain sulfur (cysteine and methionine), contributing to disulfide bonds and protein structure.
💡 NCERT Memory Line:
Amino acids are the building blocks of proteins; lipids include fats and phospholipids like lecithin, which contain phosphorus.
If the distance between two consecutive base pairs
is 0.34 nm and the total number of base pairs of a
DNA double helix in a typical mammalian cell is
6.6×109 bp, then the length of the DNA is
approximately:
