The scientist who proposed the 'lock and key' model of enzyme action was:
A. Maud Menten
B. Leonor Michaelis
C. Daniel Koshland
D. Emil Fischer
Answer: Option D
Solution (By JKExamLibrary)
Emil Fischer proposed the lock-and-key model in 1894, suggesting that the enzyme's active site is exactly complementary to the substrate, like a key fits a lock. Koshland later proposed the induced fit model, which is more widely accepted. Michaelis and Menten developed enzyme kinetics equations.
Explanation:
The terminal (apical) bud, containing the shoot apical meristem, is covered by young leaf primordia, which protect the delicate meristematic tissue. The root cap protects the root apical meristem. Leaf primordia develop into leaves. Terminal buds are often dormant in winter.
Explanation:
A mature embryo sac (female gametophyte) in angiosperms is 7-celled but 8-nucleate: 3 antipodal cells (3 nuclei), 2 synergids (2 nuclei), 1 egg cell (1 nucleus), and 1 central cell with 2 polar nuclei. Thus total 8 haploid nuclei. The central cell is homodiploid (2 polar nuclei). Double fertilization involves these nuclei. This is typical of Polygonum type of development.
Explanation:
The Fluid Mosaic Model of the plasma membrane was proposed by S. Jonathan Singer and Garth Nicolson in 1972. It describes the cell membrane as a dynamic, fluid structure composed of a phospholipid bilayer with globular proteins embedded or attached, moving laterally within the lipid matrix.
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