The "Lock and Key Model" is a scientific concept used to explain how enzymes and substrates interact. In this model, the enzyme is likened to a lock, while the substrate is compared to a key. Only the correct substrate, which fits perfectly into the enzyme's active site, can trigger a biochemical reaction, much like how a specific key can open a particular lock. This model emphasizes the specificity of enzyme action, meaning that each enzyme only works with a specific substrate. This concept is crucial in fields like biochemistry and molecular biology, as it helps scientists understand how enzymes catalyze reactions in living organisms.