photosynthesis

lactate--->fermentation in human muscleethanol--->fermentation in yeast and bacteriaacetyl CoA--->aerobic oxidationIn the presence of oxygen, human cells carry out aerobic respiration, which yields acetyl CoA. In the absence of oxygen, human cells can carry out lactic acid fermentation, which yields lactate. Yeasts and many bacteria carry out alcohol fermentation, which takes place under anaerobic conditions, and produces ethanol.

lactate and NAD+

reactants--->pyruvate and NADHproducts--->NAD+ and lactateWhen an animal engages in strenuous usage of its muscles, anaerobic conditions ensue, and pyruvate is reduced to lactate. In the process, NADH is oxidized to NAD+. This NAD+ can further oxidize glyceraldehyde-3-phosphate to produce more ATP.