Which one of the following is not a breakdown product of glucose during respiration?

During cellular respiration, glucose is broken down through various metabolic pathways depending on the availability of oxygen. In aerobic respiration, glucose is completely oxidized in the presence of oxygen to produce carbon dioxide, water, and a significant amount of energy (ATP) [2]. In anaerobic conditions, such as during fermentation in yeast, glucose is converted into ethanol and carbon dioxide [1]. In human muscle cells during intense activity, a lack of oxygen leads to the conversion of pyruvate into lactic acid. While ethanol, lactic acid, and water are all recognized breakdown products of glucose metabolism across different organisms and conditions, methanol is not a product of these respiratory pathways [1]. Methanol is a toxic alcohol typically produced through industrial processes or the breakdown of pectin, but it does not feature in the standard glycolytic or respiratory cycles of living cells.

Sources

1. [2] Science-Class VII . NCERT(Revised ed 2025) > Chapter 10: Life Processes in Plants > 10.4 Do Plants Respire? > p. 149
2. [1] Science , class X (NCERT 2025 ed.) > Chapter 5: Life Processes > Activity 5.5 > p. 87