Fischer's lock and key theory' postulates that:

Ans. A. Active site in enzyme exists in proper conformation to the substrate molecule even in absence of substratea. Fischer's lock and key theory for action of enzymes is also called rigid template model.b. The Fischer's lock and key theory explains the specificity of enzyme substrate interactions-c. The Fischer's model fails to explain the dynamic changes in the structure of enzyme that are required for catalysis.d. These are explained by the induced fit model given by Koshland.