When oxygen is absent, the end-product of glycolysis is converted toMultiple Choicelactic acid.acetic acid.CO2 and H2O.amino acids.hydrochloric acid.

Analyzing the Question

The question asks about the end-product of glycolysis when oxygen is absent, which pertains to anaerobic respiration.

Relevant Concepts

In glycolysis, glucose is broken down into pyruvate. In the presence of oxygen, pyruvate is further oxidized in the mitochondria, whereas in the absence of oxygen, anaerobic fermentation processes occur.

Analysis and Detailed Explanation

1. Glycolysis Process:

   • Glucose (C₆H₁₂O₆) is converted into two molecules of pyruvate (C₃H₄O₃).
   • This process yields 2 ATP and 2 NADH.

2. Oxygen Presence:

   • In aerobic conditions, pyruvate undergoes oxidative phosphorylation to produce ATP in the mitochondria.

3. Oxygen Absence:

   • Without oxygen, pyruvate cannot enter the citric acid cycle.
   • Instead, it undergoes fermentation.

4. Lactic Acid Fermentation:

   • In animals, pyruvate is converted to lactate (lactic acid) by the enzyme lactate dehydrogenase.
   • This process regenerates NAD⁺ allowing glycolysis to continue producing ATP without oxygen.

Verification and Summary

• The conversion of pyruvate to lactic acid occurs in anaerobic conditions, confirming that the end-product of glycolysis when oxygen is not available is indeed lactic acid.

Final Answer

The end-product of glycolysis when oxygen is absent is lactic acid.