Mitochondria are often called as the ……… of the cell.

Explanation

**Step-by-Step Solution:**

1. **Identify the Organelles**: Understand that mitochondria are a type of cell organelle found in eukaryotic cells.

2. **Function of Mitochondria**: Recognize that the primary function of mitochondria is to generate energy in the form of ATP (adenosine triphosphate).

3. **Process of Energy Production**: Acknowledge that mitochondria produce ATP through a process called cellular respiration, which involves the breakdown of glucose and other molecules.

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