(59) 12. Respiration (Cambridge IGCSE Biology 0610 for exams in 2023, 2024 and 2025)

Respiration

A chemical process in which glucose is broken down to release energy for cellular processes.

Enzymes

Proteins that control the process of respiration by catalyzing chemical reactions.

Aerobic Respiration

Respiration that takes place in the presence of oxygen, breaking down glucose to release energy, producing carbon dioxide and water.

Anaerobic Respiration

Respiration that occurs without oxygen, producing energy from glucose with byproducts such as lactic acid or alcohol and carbon dioxide.

Oxygen Debt

The temporary shortage of oxygen in the body during vigorous exercise, which leads to anaerobic respiration to provide energy.

Methylene Blue

A dye used as an indicator in experiments to determine the rate of respiration based on color change.

Rate of Respiration

The speed at which respiration occurs, measured by the time taken for indicators to change color in experiments.

Denaturation

The process in which enzymes lose their natural structure and function, typically due to high temperatures.

Glucose

A simple sugar that is a primary energy source for cellular respiration.

Lactic Acid

A byproduct of anaerobic respiration in muscle cells, which can cause muscle fatigue.

Word Equation for Aerobic Respiration

Glucose + Oxygen → Carbon Dioxide + Water + Energy.

Balanced Chemical Equation for Aerobic Respiration

C6H12O6 + 6O2 → 6CO2 + 6H2O + Energy.

Word Equation for Anaerobic Respiration in Yeast

Glucose → Alcohol + Carbon Dioxide.

Balanced Chemical Equation for Anaerobic Respiration in Yeast

C6H12O6 → 2C2H5OH + 2CO2.

Effect of Temperature on Respiration

As temperature increases, the rate of respiration generally increases until a certain point (optimal temperature), after which it decreases.

Energy Uses in Living Organisms

Includes muscle contraction, protein synthesis, cell division, active transport, growth, nerve impulse transmission, and maintaining body temperature.