AP BIOLOGY

Detailed explanation-1: -The concentration of a substance is the quantity of solute present in a given quantity of solution. Concentrations are usually expressed in terms of molarity, defined as the number of moles of solute in 1 L of solution.

Detailed explanation-2: -The half-life of a reaction is the time required for a reactant to reach one-half its initial concentration or pressure. For a first-order reaction, the half-life is independent of concentration and constant over time.

Detailed explanation-3: -The half-life of a substance in a certain enzyme catalysed reaction is 138 s. The time required for the concentration of the substance to fall from 1.28 mg L-1 is. 414 s.

Detailed explanation-4: -Enzyme catalysed reactions are of first order at high concentration of substrate and of second order at low concentration of substrate. Q. Rate of reaction (r) is plotted against temperature (T) for an enzyme catalysed reaction.