Question

Differentiate between:
(a) Respiration and Combustion 
(b) Glycolysis and Krebs’ cycle 
(c) Aerobic respiration and Fermentation

Answer 1

(a) Respiration and combustion

Respiration		Combustion
1.	It is a biochemical process.	1.	It is a physiochemical process.
2.	It occurs in the living cells.	2.	It does not occur in the living cells.
3.	ATP is generated	3.	ATP is not generated.
4.	Enzymes are required	4.	Enzymes are not required.
5.	It is a biologically controlled process.	5.	It is an uncontrolled process.

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(b) Glycolysis and Krebs cycle 

Glycolysis		Krebs cycle
1.	It is a linear pathway.	1.	It is a cyclic pathway.
2.	It occurs in the cell cytoplasm.	2.	It occurs in the mitochondrial matrix.
3.	It occurs in both aerobic and anaerobic respiration.	3.	It occurs in aerobic respiration.
4.	It generates 2 NADH2 and 2 ATP molecules on the breakdown of one glucose molecule.	4.	It produces 6 NADH2, 2FADH2, and 2 ATP molecules on the breakdown of two acetyl-CoA molecules.

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(c) Aerobic respiration and fermentation 

Aerobic respiration		Fermentation
1.	Oxygen is used for deriving energy	1.	Occurs in the absence of oxygen.
2.	Occurs in the cytoplasm and mitochondria	2.	Occurs in the cytoplasm.
3.	End products are carbon dioxide and water	3.	End products are ethyl alcohol and carbon dioxide.
4.	Complete oxidation of the respiratory substrate takes place	4.	Incomplete oxidation of the respiratory substrate takes place
5.	About 36 ATP molecules are produced	5.	Only 2 ATP molecules are produced.