Question

1. why is enzyme action similar to the action of a key fitting into a lock?

Explanation:

Enzymes have specific active - sites. Substrates have complementary shapes. Just as a key has a unique shape that fits a specific lock, a substrate's shape is complementary to the enzyme's active - site, allowing for a specific binding.

Answer:

Enzymes have specific active - sites with shapes complementary to their substrates, similar to how a key's shape is specific to a lock.