Enzymes are highely……………………in action.

Answer

To solve the question "Enzymes are highly……………………in action," we can follow these steps:

### Step 1: Understand what enzymes are
Enzymes are biological catalysts that speed up chemical reactions in living organisms. They are primarily made up of proteins.

### Step 2: Identify the characteristics of enzymes
One of the key characteristics of enzymes is their specificity. This means that each enzyme is designed to catalyze a specific type of reaction.

### Step 3: Provide examples to illustrate specificity
For instance, pepsin is an enzyme that catalyzes the breakdown of proteins, while lipase is an enzyme that catalyzes the breakdown of fats. Each enzyme works on a specific substrate and cannot catalyze reactions for other types of substrates.

### Step 4: Conclude with the answer
Based on the understanding of enzymes and their characteristics, we can fill in the blank: "Enzymes are highly **specific** in action."

### Final Answer:
Enzymes are highly specific in action.

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