12.2.1
Respiration Reactions
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Respiration
Respiration is an exothermic reaction (releases energy) that supplies all the energy needed by living organisms. This reaction happens continuously in all living cells. The reaction can be aerobic (with oxygen) or anaerobic (without oxygen).

Aerobic respiration (with oxygen)
- In aerobic respiration, glucose reacts with oxygen in the mitochondria of cells to give carbon dioxide, water and energy.
- Glucose + oxygen → carbon dioxide + water
- C6H12O6 + 6O2 → 6CO2 + 6H20

Anaerobic respiration in animals
- In animals, glucose is converted to lactic acid:
- Glucose → lactic acid
- Anaerobic respiration happens when not enough oxygen reaches the muscles during periods of intense activity.

Anaerobic respiration in yeast
- In yeast cells, glucose is converted into ethanol and carbon dioxide.
- Glucose → ethanol + carbon dioxide
- C6H12O6 → 2C2H5OH + 2CO2
- This process is called fermentation and is used to make bread and alcohol.
1Classification of Living Organisms
1.1Characteristics of Living Organisms
1.2Concept and Uses of Classification Systems
2Organisation of the Organism
2.1Cell Structure
3Movement Into & Out of Cells
3.2Osmosis
4Biological Molecules
5Enzymes
6Plant Nutrition
6.1Photosynthesis
6.1.1Photosynthesis6.1.2Photosynthesis - Plant Gas Exchange6.1.3Photosynthesis in Farming6.1.4Uses of Glucose6.1.5Ion Deficiency Conditions6.1.6Rate of Photosynthesis6.1.7Photosynthesis Experiments6.1.8Photosynthesis Equation6.1.9Photosynthesis - Calculations6.1.10Limiting Factors6.1.11Grade 9 - Photosynthesis Experiment6.1.12Exam-Style Questions - Photosynthesis
7Human Nutrition
7.2Digestive System
7.3Physical Digestion
7.4Chemical Digestion
7.5Absorption
8Transport in Plants
8.1Xylem & Phloem
8.2Water Uptake
8.3Transpiration
9Transport in Animals
9.1Circulatory Systems
9.2Heart
9.3Blood Vessels
10Diseases & Immunity
10.1Diseases & Immunity
11Gas Exchange in Humans
12Respiration
13Excretion in Humans
14Coordination & Response
14.1Coordination & Response
14.2Sense Organs
14.3Hormones
14.4Homeostasis
14.4.1Homeostasis14.4.2Regulating Internal Conditions14.4.3Control Systems14.4.4Negative Feedback14.4.5Thermoregulation14.4.6Thermoregulation - Hot and Cold14.4.7Thermoregulation - Skin14.4.8Thermoregulation - Sweating & Shivering14.4.9Thermoregulation - Hairs14.4.10Thermoregulation - Blood Vessels14.4.11Blood Glucose14.4.12Detecting Glucose14.4.13Type 1 Diabetes14.4.14End of Topic Test - Homeostasis & Hormones14.4.15Grade 9 - Hormonal Coordination
16Reproduction
16.1Asexual Reproduction
16.2Sexual Reproduction
16.3Sexual Reproduction in Plants
16.4Sexual Reproduction in Humans
16.5Sex Hormones in Humans
16.6Sexually Transmitted Infections
17Inheritance
17.1Chromosomes, Genes & Proteins
17.2Mitosis & Meiosis
17.3Monohybrid Inheritance
17.3.1Alleles17.3.2Phenotype17.3.3Sex Determination17.3.4Monohybrid Inheritance17.3.5Punnett Square17.3.6Blood Groups17.3.7Sex-linked Disorders17.3.8Cystic Fibrosis17.3.9Cystic Fibrosis - Punnett Square17.3.10Cystic Fibrosis - Pedigree Diagram17.3.11Test Crosses17.3.12End of Topic Test - Genes & Inheritance
18Variation & Selection
18.1Variation
18.2Adaptive Features
19Organisms & Their Environment
19.1Energy Flow
19.2Food Chains & Food Webs
19.3Nutrient Cycles
20Human Influence on Ecosystems
20.1Food Supply
20.2Habitat Destruction
20.3Pollution
21Biotechnology & Genetic Modification
21.1Biotechnology & Genetic Modification
Jump to other topics
1Classification of Living Organisms
1.1Characteristics of Living Organisms
1.2Concept and Uses of Classification Systems
2Organisation of the Organism
2.1Cell Structure
3Movement Into & Out of Cells
3.2Osmosis
4Biological Molecules
5Enzymes
6Plant Nutrition
6.1Photosynthesis
6.1.1Photosynthesis6.1.2Photosynthesis - Plant Gas Exchange6.1.3Photosynthesis in Farming6.1.4Uses of Glucose6.1.5Ion Deficiency Conditions6.1.6Rate of Photosynthesis6.1.7Photosynthesis Experiments6.1.8Photosynthesis Equation6.1.9Photosynthesis - Calculations6.1.10Limiting Factors6.1.11Grade 9 - Photosynthesis Experiment6.1.12Exam-Style Questions - Photosynthesis
7Human Nutrition
7.2Digestive System
7.3Physical Digestion
7.4Chemical Digestion
7.5Absorption
8Transport in Plants
8.1Xylem & Phloem
8.2Water Uptake
8.3Transpiration
9Transport in Animals
9.1Circulatory Systems
9.2Heart
9.3Blood Vessels
10Diseases & Immunity
10.1Diseases & Immunity
11Gas Exchange in Humans
12Respiration
13Excretion in Humans
14Coordination & Response
14.1Coordination & Response
14.2Sense Organs
14.3Hormones
14.4Homeostasis
14.4.1Homeostasis14.4.2Regulating Internal Conditions14.4.3Control Systems14.4.4Negative Feedback14.4.5Thermoregulation14.4.6Thermoregulation - Hot and Cold14.4.7Thermoregulation - Skin14.4.8Thermoregulation - Sweating & Shivering14.4.9Thermoregulation - Hairs14.4.10Thermoregulation - Blood Vessels14.4.11Blood Glucose14.4.12Detecting Glucose14.4.13Type 1 Diabetes14.4.14End of Topic Test - Homeostasis & Hormones14.4.15Grade 9 - Hormonal Coordination
16Reproduction
16.1Asexual Reproduction
16.2Sexual Reproduction
16.3Sexual Reproduction in Plants
16.4Sexual Reproduction in Humans
16.5Sex Hormones in Humans
16.6Sexually Transmitted Infections
17Inheritance
17.1Chromosomes, Genes & Proteins
17.2Mitosis & Meiosis
17.3Monohybrid Inheritance
17.3.1Alleles17.3.2Phenotype17.3.3Sex Determination17.3.4Monohybrid Inheritance17.3.5Punnett Square17.3.6Blood Groups17.3.7Sex-linked Disorders17.3.8Cystic Fibrosis17.3.9Cystic Fibrosis - Punnett Square17.3.10Cystic Fibrosis - Pedigree Diagram17.3.11Test Crosses17.3.12End of Topic Test - Genes & Inheritance
18Variation & Selection
18.1Variation
18.2Adaptive Features
19Organisms & Their Environment
19.1Energy Flow
19.2Food Chains & Food Webs
19.3Nutrient Cycles
20Human Influence on Ecosystems
20.1Food Supply
20.2Habitat Destruction
20.3Pollution
21Biotechnology & Genetic Modification
21.1Biotechnology & Genetic Modification
Practice questions on Respiration Reactions
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