OCR GCSE Biology Practice Exam 2026 – Comprehensive All-in-One Guide to Exam Success

During anaerobic respiration in plants and microbes, the end products are ethanol and carbon dioxide. This process occurs when oxygen is not available, allowing organisms to convert sugars into energy through fermentation.

In plants and some yeast, glucose is broken down in absence of oxygen, leading to the production of ethanol (alcohol) and carbon dioxide. This is notably different from aerobic respiration, which produces carbon dioxide and water in the presence of oxygen. The production of ethanol is particularly important in the brewing and baking industries, where yeast ferments sugars to generate alcohol and causes dough to rise.

This process can be contrasted with lactic acid fermentation, which occurs in animals and some bacteria, producing lactic acid when glucose is metabolized anaerobically. However, lactic acid is not a product of plant or microbial anaerobic respiration. The options that mention oxygen or water are inaccurate because anaerobic respiration specifically occurs in the absence of oxygen, and thus those products would not be generated.