Respiration is considered an exothermic reaction because it releases energy in the form of heat and chemical energy (ATP). During respiration, glucose (C₆H₁₂O₆) is broken down by oxidation in the presence of oxygen, releasing energy. The reaction: C₆H₁₂O₆ + 6O₂ → 6CO₂ + 6H₂O + Energy. Since energy is released to the surroundings, it is classified as an exothermic reaction.
Respiration is exothermic because it releases energy (heat + ATP) to the surroundings.
Equation: C₆H₁₂O₆ + 6O₂ → 6CO₂ + 6H₂O + Energy (~2870 kJ/mol).
Energy is stored in chemical bonds of glucose and released when glucose is oxidised.
Respiration releases energy slowly (enzyme-controlled steps); combustion releases it rapidly.
About 40% of released energy is captured in ATP; 60% is released as heat.
Aerobic respiration produces 38 ATP molecules per glucose molecule.
Anaerobic respiration is also exothermic but releases far less energy (2 ATP).
The heat released in respiration helps maintain body temperature in warm-blooded animals.
An exothermic reaction is one that releases energy (heat) to the surroundings.
In respiration: • Glucose is oxidised (broken down) using oxygen. • Chemical bonds in glucose are broken and new, more stable bonds form in CO₂ and H₂O. • The energy stored in glucose bonds is released as: – Heat (warms the body) – Chemical energy stored in ATP (used for cellular work)
Reaction: C₆H₁₂O₆ + 6O₂ → 6CO₂ + 6H₂O + Energy (≈ 2870 kJ/mol)
Energy is released, not absorbed → exothermic.
Since energy is released from organic molecules (glucose) and transferred to the surroundings (body heat) and to ATP molecules, respiration is classified as exothermic.
Both respiration and combustion of glucose are exothermic:
Combustion (burning): C₆H₁₂O₆ + 6O₂ → 6CO₂ + 6H₂O + heat (all at once, very fast)
Respiration (cellular): C₆H₁₂O₆ + 6O₂ → 6CO₂ + 6H₂O + energy (slowly, in controlled steps)
Key difference: • Combustion releases all energy as heat suddenly. • Respiration releases energy in a stepwise, controlled manner through a series of enzyme-controlled reactions (glycolysis, Krebs cycle, oxidative phosphorylation). • Energy is captured in ATP molecules (adenosine triphosphate) for use in biological processes.
Both are exothermic — energy flows OUT of the glucose molecule. But respiration is more efficient — it captures ~40% of the energy in ATP; the rest is released as heat.
The energy released during respiration (stored in ATP) is used for:
Types of respiration:
Aerobic respiration (with oxygen): C₆H₁₂O₆ + 6O₂ → 6CO₂ + 6H₂O + 38 ATP Energy ≈ 2870 kJ/mol — highly exothermic
Anaerobic respiration (without oxygen): In yeast: C₆H₁₂O₆ → 2C₂H₅OH + 2CO₂ + 2 ATP In muscles: C₆H₁₂O₆ → 2 lactic acid + 2 ATP Less energy released — less exothermic but still releases energy
Respiration is exothermic because it releases energy to the surroundings. During respiration, glucose is oxidised: C₆H₁₂O₆ + 6O₂ → 6CO₂ + 6H₂O + Energy. The energy stored in glucose's chemical bonds is released as heat and ATP. Since energy is released (not absorbed), it is an exothermic reaction.
Both are exothermic reactions that oxidise glucose to CO₂ and H₂O. Combustion releases all energy as heat rapidly. Respiration releases energy slowly through controlled enzyme steps, capturing ~40% as ATP and releasing ~60% as heat. Respiration is more efficient and controlled.
Aerobic respiration of one mole of glucose releases approximately 2870 kJ of energy. About 38 ATP molecules are produced per glucose molecule. The remaining energy (~60%) is released as heat, which helps maintain body temperature.
Yes, anaerobic respiration is also exothermic but releases much less energy. In yeast: C₆H₁₂O₆ → 2C₂H₅OH + 2CO₂ + 2 ATP. In muscle cells: glucose → 2 lactic acid + 2 ATP. Only 2 ATP are produced compared to 38 in aerobic respiration.
ATP (adenosine triphosphate) is the energy currency of the cell. Energy released during respiration is stored in ATP molecules. This ATP is then used for all cellular activities — muscle contraction, active transport, biosynthesis, nerve impulses, and cell division.
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