Which of the following equations summarises the conversion of glucose to lactic acid? A - Scottish Highers Human Biology - Question 7 - 2017

The conversion of glucose to lactic acid primarily occurs through the process of fermentation, specifically lactic acid fermentation. The reaction can be represented as follows:

1. Glycolysis: In the first step, glucose is broken down into pyruvate. This process consumes 2 ATP molecules and produces 4 ATP and 2 NADH molecules, thereby yielding a net gain of 2 ATP.

2. Conversion to Lactic Acid: In the absence of oxygen, pyruvate is then reduced to lactic acid with the help of NADH, which is oxidized back to NAD+. This is crucial as it regenerates NAD+ for glycolysis to continue.

Thus, the correct equation is option C:

ightarrow ext{pyruvate} ightarrow ext{lactic acid}$$ $$ ext{ADP + Pi} ightarrow ext{ATP}$$ $$ ext{NADH} ightarrow ext{NAD}$$