Fermentation — Science definition
A pathway regenerating NAD⁺ to sustain glycolysis without adding further ATP.
Where it is taught
- Cellular Respiration — Matter & Energy in Living Systems, Life Science: Biology, Grade 10
In use
Without oxygen, some cells use fermentation to regenerate NAD⁺ and sustain glycolysis’s net two ATP; fermentation itself adds no additional ATP.
Cellular Respiration
Questions using fermentation
Problem 1
Using model yields of 30 ATP per glucose aerobically and 2 from glycolysis supported by fermentation, how many times as much ATP is obtained aerobically?
Answer and explanation
15 times
30 ÷ 2 = 15 under the stated model.
Problem 2
Why can fermentation help glycolysis continue when oxygen-dependent pathways are unavailable? Show the reasoning, not just the conclusion.
Hints
Atoms and energy must be accounted for separately.
Answer and explanation
It regenerates NAD⁺ needed for glycolysis, with products depending on the organism/pathway.
Problem 3
Fermentation allows a cell to
- produce as much ATP as aerobic respiration
- continue making a small amount of ATP without oxygen
- produce oxygen
- avoid using glucose
Answer and explanation
continue making a small amount of ATP without oxygen
Fermentation regenerates the carriers glycolysis needs so that a small ATP yield continues without oxygen; it does not approach the aerobic yield.