Who gave the definite proof of life arising feom pre-existing life?

Options

A. Redi
B. Spallanzani
C. Pasteur
D. Cuvier

Answer

To solve the question "Who gave the definite proof of life arising from pre-existing life?", we can follow these steps:

### Step-by-Step Solution:

1. **Understanding the Concept**: The question is asking about a scientist who provided evidence that life does not spontaneously arise from non-living matter, but rather comes from existing life forms.

2. **Identifying Key Experiments**: The most notable experiment related to this concept is the one conducted by Louis Pasteur. His work is crucial in disproving the theory of spontaneous generation.

3. **Describing Pasteur's Experiment**:
- Pasteur used a specially designed flask with a long neck.
- In his first experiment, he boiled a nutrient broth in the flask and left it in an upright position. After cooling, no bacteria grew in the broth, indicating that no life had spontaneously arisen.
- In the second experiment, he boiled the broth again but allowed it to cool with the neck of the flask exposed to air. This time, bacteria appeared in the broth, demonstrating that the bacteria came from the air (pre-existing life).
- In a third experiment, when he tilted the flask, allowing the broth to come into contact with the neck where bacteria had settled, new bacterial growth was observed.

4. **Conclusion**: From these experiments, Pasteur concluded that life arises from pre-existing life, thus providing definitive proof against the spontaneous generation theory.

5. **Final Answer**: The scientist who gave the definite proof of life arising from pre-existing life is **Louis Pasteur**.