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Fermentation: Test Your Understanding
Teacher's Guide
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Is fermentation a chemical or biological process? Explain your answer.
Louis Pasteur showed that fermentation is a biological process because it is a physiological counterpart
of oxidation and permits organisms to live and grow in the absence of air (anaerobically).
What are the similarities and differences between fermentation and putrefaction?
Both fermentation and putrefaction involve microbes breaking down organic material in the absence
of oxygen. Fermentation is the breaking down of carbohydrates, which often yields products with
pleasant smells and tastes. On the other hand, putrefaction involves the breaking down of proteins,
which produces foul-smelling substances.
Critical Thinking: Explain why fermentation might have evolved in primitive organisms before
cellular respiration.
Sample answer: Fermentation most likely evolved before cellular respiration in primitive organisms
because there was very little oxygen in the environment when life first arose on Earth. Fermentation
would have allowed organisms to survive in the absence of oxygen. As the atmosphere changed,
oxygen became more abundant, and cellular respiration evolved.
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