Sigmoidal plots of activity versus substrate concentration are exhibited by a. holoenzymes. b. Michaelis-Menten enzymes. c. allosteric enzymes. d. monomeric enzymes. e. isozymes.

The correct answer is C

Explanation:

Allosteric enzyme is an enzyme that has more than one active site on the surface of the enzyme. Generally, the binding to one of these active sites affects the affinity of the other active sites on the enzyme; this causes the enzyme not to follow the Michaelis-Menten's enzyme kinetics. Thus, when the activity versus substrate is plotted on a graph, a sigmoidal curve shown instead of an hyperbolic curve (like other enzymes).  

meteorologists would compare a new weather map with one 24 h old to see how fast a front is moving.