............ catalyse covalent bonding between two molecules to form a large molecule.

Explanation

To answer the question, "............ catalyse covalent bonding between two molecules to form a large molecule," we need to identify the specific type of enzyme that facilitates this process. Here’s a step-by-step breakdown of the solution:

### Step-by-Step Solution:

1. **Understanding Enzymes**: Enzymes are biological catalysts that speed up chemical reactions in living organisms. They can be classified into different categories based on the type of reaction they catalyze.

2. **Categories of Enzymes**: There are six main categories of enzymes. Each category has a specific function. For this question, we are interested in the category that involves the formation of covalent bonds.

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