Chapter 5 · Question 11
What are the different ways in which glucose is oxidized to provide energy in various organisms?
Q11
What are the different ways in which glucose is oxidized to provide energy in various organisms?
Answer Revealed
Direct Answer:
Glucose is oxidised in three ways: aerobic respiration (with O2, producing CO2 + H2O + 38 ATP), anaerobic respiration (without O2, producing ethanol + CO2 + 2 ATP in yeast, or lactic acid + 2 ATP in muscle cells).
Simple Explanation
Glucose can be broken down in three ways: 1. With oxygen — this gives the most energy. 2. Without oxygen in yeast — this makes alcohol. 3. Without oxygen in our muscles — this makes lactic acid (causing cramps).
Exam-Ready Structure
Glucose (a six-carbon molecule) is broken down to release energy through three different pathways: 1. Aerobic respiration — In the presence of oxygen, glucose is completely oxidized to carbon dioxide and water, releasing a large amount of energy (38 ATP molecules per glucose molecule). This occurs in mitochondria. 2. Anaerobic respiration in yeast — In the absence of oxygen, glucose is converted to ethanol and carbon dioxide, releasing only 2 ATP per glucose molecule (fermentation). 3. Anaerobic respiration in muscle cells — During heavy exercise when oxygen supply is insufficient, glucose is converted to lactic acid, releasing only 2 ATP per glucose molecule. The accumulation of lactic acid causes muscle cramps.
Key Points
- Aerobic: glucose → CO2 + H2O + 38 ATP (in mitochondria)
- Anaerobic (yeast): glucose → ethanol + CO2 + 2 ATP
- Anaerobic (muscles): glucose → lactic acid + 2 ATP
- Aerobic respiration releases far more energy than anaerobic
Common Mistakes
- Saying anaerobic respiration produces the same energy as aerobic
- Confusing the end products of yeast fermentation and muscle respiration
Answer Sources
- Aerobic and anaerobic breakdown of glucosetextbook section | Science | Life Processes | Respiration pathways | Pages 10-11