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Respiration - Aerobic respiration

Grade 11IGCSEBiology

Review the key concepts, formulae, and examples before starting your quiz.

🔑Concepts

Aerobic respiration is defined as the chemical reactions in cells that use oxygen to break down nutrient molecules to release a relatively large amount of energy.

The primary nutrient molecule used is glucose, which has the chemical formula C6H12O6C_6H_{12}O_6.

The process involves a series of enzyme-controlled reactions that occur in the cytoplasm (glycolysis) and primarily within the mitochondria.

The energy released is stored in the form of ATPATP (adenosine triphosphate), which powers cellular processes like protein synthesis, muscle contraction, and active transport.

The waste products of aerobic respiration are carbon dioxide (CO2CO_2) and water (H2OH_2O), which must be excreted from the organism.

Aerobic respiration is much more efficient than anaerobic respiration, yielding significantly more energy per molecule of glucose (approximately 2880 kJ/mol2880\ kJ/mol).

📐Formulae

Glucose+OxygenCarbon dioxide+Water(+Energy)Glucose + Oxygen \rightarrow Carbon\ dioxide + Water (+ Energy)

C6H12O6+6O26CO2+6H2OC_6H_{12}O_6 + 6O_2 \rightarrow 6CO_2 + 6H_2O

💡Examples

Problem 1:

Calculate the total number of oxygen (O2O_2) molecules required to completely respire 55 molecules of glucose (C6H12O6C_6H_{12}O_6) aerobically.

Solution:

3030 molecules of O2O_2

Explanation:

According to the balanced chemical equation C6H12O6+6O26CO2+6H2OC_6H_{12}O_6 + 6O_2 \rightarrow 6CO_2 + 6H_2O, the molar ratio of glucose to oxygen is 1:61:6. Therefore, for 55 molecules of glucose, the oxygen required is 5×6=305 \times 6 = 30 molecules.

Problem 2:

Identify the number of carbon dioxide molecules produced when 0.5 mol0.5\ mol of glucose is used in aerobic respiration.

Solution:

3.0 mol3.0\ mol of CO2CO_2

Explanation:

Based on the equation C6H12O6+6O26CO2+6H2OC_6H_{12}O_6 + 6O_2 \rightarrow 6CO_2 + 6H_2O, one mole of glucose produces 66 moles of CO2CO_2. Thus, 0.5 mol×6=3.0 mol0.5\ mol \times 6 = 3.0\ mol of CO2CO_2.

Aerobic respiration - Revision Notes & Key Diagrams | IGCSE Grade 11 Biology