Anaerobic respiration occurs in conditions with limited oxygen supply or absence of oxygen. During anaerobic respiration in plant cells, glucose is not fully oxidized to carbon dioxide and water but is partly broken down into ethanol and carbon dioxide. Fermentation of 5% glucose solution produced the highest amount of carbon dioxide and rate of fermentation compared to 10% and 15% solutions over 10 minutes, as higher glucose concentrations increase fermentation time and decrease glucose uptake rate.