Which conditions would be best for the fermentation of sugars by yeast? (A) Low oxygen concentration and a temperature between 25°C and 35°C (B) High oxygen concentration and a temperature between 25°C and 35°C (C) Low oxygen concentration and a temperature between 45°C and 60°C (D) High oxygen concentration and a temperature between 45°C and 60°C - HSC - SSCE Chemistry - Question 1 - 2002 - Paper 1

To determine the best conditions for the fermentation of sugars by yeast, we need to understand the role of oxygen and temperature in the fermentation process.

1. Oxygen Concentration: Yeast fermentation is an anaerobic process, meaning it occurs best in low oxygen conditions. High oxygen concentrations can lead to aerobic respiration, which is less efficient for sugar breakdown compared to fermentation.

2. Temperature: Yeast typically ferments effectively at temperatures ranging from 25°C to 35°C. Temperatures above 35°C can stress the yeast and lead to reduced fermentation efficiency or even kill the yeast if it exceeds 45°C.

Based on these points, the best choice would be Option (A): Low oxygen concentration and a temperature between 25°C and 35°C.