Asap explain why a key that fits into a lock is a useful model for the function of enzymes.

Keys(enzymes) are  specific to certain locks(substrate)

Explanation:

The key and lock model are used to illustrate the enzyme specificity to a substrate function. Enzymes are specific in the reactions they catalyze. An enzyme will only catalyze one specific reaction or a group of closely related reactions.

For enzymes to catalyze a reaction, the substrate(s) must fit in the active site on the surface of the enzyme. This forms an enzyme-substrate complex. The enzymes speed up the formation of the products. The products formed separate from the enzymes so that other substrate molecules can fit into the active sites.

if your own plato the answer is b. the fern transitioned from sporophyte generation to gametophyte generation.