Question 1: Anaerobic respiration is a process that occurs in the absence of oxygen, allowing cells to produce energy. It is used in various industrial processes and in the production of certain consumer products. Explain why anaerobic respiration is important for some products and industries.

Answer: Anaerobic respiration allows organisms and cells to produce energy when oxygen is unavailable, which is crucial in industrial processes like fermentation for producing products such as yoghurt, bread, and ethanol, enabling continuous production and preservation.

Question 1: Define anaerobic respiration.

Answer: Anaerobic respiration is a form of respiration that occurs without oxygen, where cells break down glucose to produce energy, lactic acid or ethanol, and carbon dioxide.

Question 2: Name two products that result from microbial fermentation involving anaerobic respiration.

Answer: Yoghurt and ethanol.

Question 3: Describe the main difference between aerobic and anaerobic respiration.

Answer: Aerobic respiration requires oxygen and produces more energy, while anaerobic respiration occurs without oxygen and produces less energy, along with by-products like lactic acid or ethanol.

Question 1: If a microorganism produces 2 molecules of ATP per glucose molecule during anaerobic respiration, how much energy (in kJ) is produced from the breakdown of 1 mole of glucose? (Use 1 ATP ≈ 30.5 kJ).

Answer: 61 kJ

Question 1: Describe a simple experiment to test the effect of pH on yeast fermentation producing ethanol. Include the variables you would control and safety precautions.

Answer: The experiment involves setting up several fermentation tubes with yeast and sugar solution at different pH levels, controlling temperature, yeast amount, and sugar concentration. Measure ethanol production over time using appropriate methods. Safety precautions include handling alcohol safely, working in a well-ventilated area, and wearing protective equipment.

Question 1: A fermentation process produces 0.8 litres of ethanol in 24 hours using 1 kg of sugar. Calculate the volume of ethanol produced per gram of sugar. (Assume 1 kg of sugar produces 1 litre of ethanol).

Answer: 0.8 ml per gram

Question 1: Explain how anaerobic respiration contributes to the production of consumer products like bread and alcohol. Include the biochemical process and practical implications. (6 marks)

Answer: Anaerobic respiration in yeast and bacteria allows the breakdown of sugars without oxygen, producing ethanol and carbon dioxide. In bread-making, CO₂ causes dough to rise, while ethanol and other products are used in alcohol production. This process enables continuous fermentation in industry, especially where oxygen supply is limited, and influences product consistency and efficiency.

Question 1: Many sports drinks contain electrolytes and sometimes include products of anaerobic respiration such as lactic acid. Explain how understanding anaerobic respiration can help improve the formulation of sports drinks for athletes during intense exercise.

Answer: Understanding anaerobic respiration helps in designing sports drinks that replenish lost electrolytes and manage lactic acid buildup, which occurs during anaerobic respiration in muscles. Proper formulation can delay fatigue, improve recovery, and enhance athletic performance.