Ingrowths of plasma membrane of a bacterium are called polysome/mesosomes.

Explanation

To determine whether the ingrowths of the plasma membrane of a bacterium are called polysome or mesosome, we can follow these steps:

### Step-by-Step Solution:

1. **Understand the Terms**:
- **Polysome**: A polysome is a complex formed by multiple ribosomes attached to a single strand of messenger RNA (mRNA). It plays a role in protein synthesis.
- **Mesosome**: Mesosomes are the invaginations or folds of the plasma membrane in bacteria. They are associated with various functions, including cell wall formation and respiration.

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