7.2.1
Digestive System
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Enzymes in Digestion
Digestive enzymes are produced by specialised cells in the glands and the lining of the gut. They are then secreted out of the body cells and into the cavity of the digestive system.

Functions of digestive enzymes
- The digestive enzymes catalyse the breakdown of large, insoluble food molecules into smaller, soluble molecules that are then small enough to be absorbed into the bloodstream.
- Digested molecules can be used to construct new carbohydrates, proteins and lipids in the body.
- Some glucose produced by digestion is used for respiration.

Enzymes in digestion
- The three main digestive enzymes are:
- Amylase
- Protease
- Lipase

Enzymes in the small intestine
- Enzymes in the small intestine operate best in alkaline conditions.
- Bile neutralises acid from the stomach to stop these enzymes becoming denatured.

Functions of bile
- Bile breaks up fats into tiny droplets, through a process called emulsification.
- The tiny droplets have a higher surface area than the original fat drop.
- This increases the rate of the lipase-catalysed reactions that break fats down.
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 Digestive System
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- 1Human Alimentary CanalPut in order
- 2
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