In the lock-and-key model of enzyme action, the enzyme active site is thought of as .

Rigid and non flexible surface

Explanation:

Enzymes are catalyst that speeds up rate of chemical reactions, they bind to a substrate which are known as reactant substrate to speed up rate of chemical reaction and to unlock the key.

The enzyme is said to be rigid and non flexible fitting perfectly to the surface of the substrate where the reaction takes place. Fitting perfectly enable the enzyme to perform its action on the substrate unlocking the key and activating the action in the molecule.

the element that provides strength to the exoskeletons of clams and oysters is phosphorus.

this is so because calcium carbonate is the main component in the shells. calcium carbonate is strengthened by phosphorus.

explanation:

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