Define biogenesis.

Explanation

**Step-by-Step Solution:**

1. **Understanding the Concept**: Biogenesis is a fundamental concept in biology that refers to the process by which new life is produced from pre-existing life. This means that living organisms arise from other living organisms, rather than from non-living matter.

2. **Historical Context**: The theory of biogenesis was significantly advanced by scientists such as Rudolf Virchow. He proposed that all cells come from pre-existing cells, which laid the groundwork for our understanding of cellular reproduction and life processes.

3. **Key Definition**: In simple terms, biogenesis can be defined as the principle that life arises from existing life. This contrasts with the idea of abiogenesis, which suggests that life can originate from non-living matter.

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