1.2.2
Types of Polysaccharides
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Starch
Starch is a polysaccharide and a common storage compound.

Functions of starch
- Starch is the main energy storage material in plants.
- Starch is stored in the seeds of plants.
- Starch is broken down into glucose by plants when they need more energy.
- Starch can act as a source of food for humans and animals.

Features of starch
- Starch does NOT change the water potential in a cell because it's insoluble in water.

Iodine test
- A common test for the presence of starch, particularly in food testing, is to add iodine solution.
- Iodine solution is made by mixing iodine and a solution of potassium iodide.
- Step 1: Place a small sample into the dimple of a spotting tile or to a boiling tube.
- Step 2: Add a few drops of iodine solution and observe any colour change.
- If starch is present, the solution will change colour from orange → blue-black.
Glycogen
Glycogen is formed by condensation reactions of alpha-glucose molecules and is the main energy storage material in animals. It can be thought of as the animal equivalent of starch.

Function of glycogen
- Glycogen is a highly branched molecule, similar to amylopectin (a form of starch).
- When animals need to release energy, glycogen's highly branched structure means that glucose can quickly be released.

Glycogen in the human body
- Glycogen is a good storage molecule because it is so compact.
- When blood glucose levels decrease, glycogen is broken down to release glucose. This is called glycogenolysis.
Cellulose
Cellulose is the major component of cell walls in plants.

Structure of cellulose
- Cellulose is a long chain of beta-glucose.
- Beta-glucose molecules are linked by glycosidic bonds to form linear cellulose chains that are unbranched.
- Microfibrils are strong fibres that are made of many cellulose chains that are held together by hydrogen bonds.
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Function of cellulose
- Cellulose is the most abundant natural polymer.
- The cell walls of plant cells are mostly made of cellulose.
- These cell walls offer structural support because of the strength of the microfibril fibres that they are made of.

Digestion of cellulose
- Cellulose cannot be broken down by human digestive enzymes.
- Herbivores, such as cows and horses, are able to digest plant material rich in cellulose.
1Biological Molecules
1.1Monomers & Polymers
1.2Carbohydrates
1.3Lipids
1.4Proteins
1.4.1The Peptide Chain1.4.2Investigating Proteins1.4.3Primary & Secondary Protein Structure1.4.4Tertiary & Quaternary Protein Structure1.4.5Enzymes1.4.6Factors Affecting Enzyme Activity1.4.7Enzyme-Controlled Reactions1.4.8End of Topic Test - Lipids & Proteins1.4.9A-A* (AO3/4) - Enzymes1.4.10A-A* (AO3/4) - Proteins1.4.11Diagnostic Misconceptions - Enzyme Inhibitors
1.5Nucleic Acids
1.6ATP
1.7Water
1.8Inorganic Ions
2Cells
2.1Cell Structure
2.2Mitosis & Cancer
2.3Transport Across Cell Membrane
2.4Cell Recognition & the Immune System
2.4.1Immune System2.4.2Phagocytosis2.4.3T Lymphocytes2.4.4B Lymphocytes2.4.5Antibodies2.4.6Primary & Secondary Response2.4.7Vaccines2.4.8HIV2.4.9Ethical Issues2.4.10End of Topic Test - Immune System2.4.11Exam-Style Question - Immune System2.4.12A-A* (AO3/4) - Immune System2.4.13Diagnostic Misconceptions - Humoral vs Cellular
3Substance Exchange
3.1Surface Area to Volume Ratio
3.2Gas Exchange
3.3Digestion & Absorption
3.4Mass Transport
3.4.1Haemoglobin3.4.2Oxygen Transport3.4.3The Circulatory System3.4.4The Heart3.4.5Blood Vessels3.4.6Cardiovascular Disease3.4.7Heart Dissection3.4.8Xylem3.4.9Phloem3.4.10Investigating Plant Transport3.4.11End of Topic Test - Mass Transport3.4.12A-A* (AO3/4) - Mass Transport3.4.13Diagnostic Misconceptions - Concentration Gradient3.4.14Diagnostic Misconceptions - Cardiac Cycle3.4.15Diagnostic Misconceptions - Carrying Capacity3.4.16Diagnostic Misconceptions - Translocation
4Genetic Information & Variation
4.1DNA, Genes & Chromosomes
4.2DNA & Protein Synthesis
4.3Mutations & Meiosis
4.4Genetic Diversity & Adaptation
4.5Species & Taxonomy
4.6Biodiversity Within a Community
4.7Investigating Diversity
5Energy Transfers (A2 only)
5.1Photosynthesis
5.1.1Overview of Photosynthesis5.1.2Photoionisation of Chlorophyll5.1.3Production of ATP & Reduced NADP5.1.4Cyclic Photophosphorylation5.1.5Light-Independent Reaction5.1.6A-A* (AO3/4) - Photosynthesis Reactions5.1.7Limiting Factors5.1.8Photosynthesis Experiments5.1.9End of Topic Test - Photosynthesis5.1.10A-A* (AO3/4) - Photosynthesis
5.2Respiration
5.2.1Overview of Respiration5.2.2Anaerobic Respiration5.2.3A-A* (AO3/4) - Anaerobic Respiration5.2.4The Link Reaction5.2.5The Krebs Cycle5.2.6Oxidative Phosphorylation5.2.7Respiration Experiments5.2.8End of Topic Test - Respiration5.2.9A-A* (AO3/4) - Respiration5.2.10Diagnostic Misconceptions - Aerobic vs Anaerobic
5.3Energy & Ecosystems
6Responding to Change (A2 only)
6.1Nervous Communication
6.2Nervous Coordination
6.3Muscle Contraction
6.4Homeostasis
6.4.1Overview of Homeostasis6.4.2Blood Glucose Concentration6.4.3Controlling Blood Glucose Concentration6.4.4End of Topic Test - Blood Glucose6.4.5Primary & Secondary Messengers6.4.6Diabetes Mellitus6.4.7Measuring Glucose Concentration6.4.8Osmoregulation6.4.9Controlling Blood Water Potential6.4.10ADH6.4.11End of Topic Test - Diabetes & Osmoregulation6.4.12A-A* (AO3/4) - Homeostasis6.4.13Diagnostic Misconceptions - Effect of ADH
7Genetics & Ecosystems (A2 only)
7.1Genetics
7.2Populations
7.3Evolution
7.3.1Variation7.3.2Natural Selection & Evolution7.3.3End of Topic Test - Populations & Evolution7.3.4Types of Selection7.3.5Types of Selection Summary7.3.6Overview of Speciation7.3.7Causes of Speciation7.3.8Diversity7.3.9End of Topic Test - Selection & Speciation7.3.10A-A* (AO3/4) - Populations & Evolution7.3.11Diagnostic Misconceptions - Types of Speciation
8The Control of Gene Expression (A2 only)
8.1Mutation
8.2Gene Expression
8.2.1Stem Cells8.2.2Stem Cells in Disease8.2.3End of Topic Test - Mutation & Gene Epression8.2.4A-A* (AO3/4) - Mutation & Stem Cells8.2.5Regulating Transcription8.2.6Epigenetics8.2.7Epigenetics & Disease8.2.8Regulating Translation8.2.9Experimental Data8.2.10End of Topic Test - Transcription & Translation8.2.11Tumours8.2.12Correlations & Causes8.2.13Prevention & Treatment8.2.14End of Topic Test - Cancer8.2.15A-A* (AO3/4) - Gene Expression & Cancer
8.3Genome Projects
Jump to other topics
1Biological Molecules
1.1Monomers & Polymers
1.2Carbohydrates
1.3Lipids
1.4Proteins
1.4.1The Peptide Chain1.4.2Investigating Proteins1.4.3Primary & Secondary Protein Structure1.4.4Tertiary & Quaternary Protein Structure1.4.5Enzymes1.4.6Factors Affecting Enzyme Activity1.4.7Enzyme-Controlled Reactions1.4.8End of Topic Test - Lipids & Proteins1.4.9A-A* (AO3/4) - Enzymes1.4.10A-A* (AO3/4) - Proteins1.4.11Diagnostic Misconceptions - Enzyme Inhibitors
1.5Nucleic Acids
1.6ATP
1.7Water
1.8Inorganic Ions
2Cells
2.1Cell Structure
2.2Mitosis & Cancer
2.3Transport Across Cell Membrane
2.4Cell Recognition & the Immune System
2.4.1Immune System2.4.2Phagocytosis2.4.3T Lymphocytes2.4.4B Lymphocytes2.4.5Antibodies2.4.6Primary & Secondary Response2.4.7Vaccines2.4.8HIV2.4.9Ethical Issues2.4.10End of Topic Test - Immune System2.4.11Exam-Style Question - Immune System2.4.12A-A* (AO3/4) - Immune System2.4.13Diagnostic Misconceptions - Humoral vs Cellular
3Substance Exchange
3.1Surface Area to Volume Ratio
3.2Gas Exchange
3.3Digestion & Absorption
3.4Mass Transport
3.4.1Haemoglobin3.4.2Oxygen Transport3.4.3The Circulatory System3.4.4The Heart3.4.5Blood Vessels3.4.6Cardiovascular Disease3.4.7Heart Dissection3.4.8Xylem3.4.9Phloem3.4.10Investigating Plant Transport3.4.11End of Topic Test - Mass Transport3.4.12A-A* (AO3/4) - Mass Transport3.4.13Diagnostic Misconceptions - Concentration Gradient3.4.14Diagnostic Misconceptions - Cardiac Cycle3.4.15Diagnostic Misconceptions - Carrying Capacity3.4.16Diagnostic Misconceptions - Translocation
4Genetic Information & Variation
4.1DNA, Genes & Chromosomes
4.2DNA & Protein Synthesis
4.3Mutations & Meiosis
4.4Genetic Diversity & Adaptation
4.5Species & Taxonomy
4.6Biodiversity Within a Community
4.7Investigating Diversity
5Energy Transfers (A2 only)
5.1Photosynthesis
5.1.1Overview of Photosynthesis5.1.2Photoionisation of Chlorophyll5.1.3Production of ATP & Reduced NADP5.1.4Cyclic Photophosphorylation5.1.5Light-Independent Reaction5.1.6A-A* (AO3/4) - Photosynthesis Reactions5.1.7Limiting Factors5.1.8Photosynthesis Experiments5.1.9End of Topic Test - Photosynthesis5.1.10A-A* (AO3/4) - Photosynthesis
5.2Respiration
5.2.1Overview of Respiration5.2.2Anaerobic Respiration5.2.3A-A* (AO3/4) - Anaerobic Respiration5.2.4The Link Reaction5.2.5The Krebs Cycle5.2.6Oxidative Phosphorylation5.2.7Respiration Experiments5.2.8End of Topic Test - Respiration5.2.9A-A* (AO3/4) - Respiration5.2.10Diagnostic Misconceptions - Aerobic vs Anaerobic
5.3Energy & Ecosystems
6Responding to Change (A2 only)
6.1Nervous Communication
6.2Nervous Coordination
6.3Muscle Contraction
6.4Homeostasis
6.4.1Overview of Homeostasis6.4.2Blood Glucose Concentration6.4.3Controlling Blood Glucose Concentration6.4.4End of Topic Test - Blood Glucose6.4.5Primary & Secondary Messengers6.4.6Diabetes Mellitus6.4.7Measuring Glucose Concentration6.4.8Osmoregulation6.4.9Controlling Blood Water Potential6.4.10ADH6.4.11End of Topic Test - Diabetes & Osmoregulation6.4.12A-A* (AO3/4) - Homeostasis6.4.13Diagnostic Misconceptions - Effect of ADH
7Genetics & Ecosystems (A2 only)
7.1Genetics
7.2Populations
7.3Evolution
7.3.1Variation7.3.2Natural Selection & Evolution7.3.3End of Topic Test - Populations & Evolution7.3.4Types of Selection7.3.5Types of Selection Summary7.3.6Overview of Speciation7.3.7Causes of Speciation7.3.8Diversity7.3.9End of Topic Test - Selection & Speciation7.3.10A-A* (AO3/4) - Populations & Evolution7.3.11Diagnostic Misconceptions - Types of Speciation
8The Control of Gene Expression (A2 only)
8.1Mutation
8.2Gene Expression
8.2.1Stem Cells8.2.2Stem Cells in Disease8.2.3End of Topic Test - Mutation & Gene Epression8.2.4A-A* (AO3/4) - Mutation & Stem Cells8.2.5Regulating Transcription8.2.6Epigenetics8.2.7Epigenetics & Disease8.2.8Regulating Translation8.2.9Experimental Data8.2.10End of Topic Test - Transcription & Translation8.2.11Tumours8.2.12Correlations & Causes8.2.13Prevention & Treatment8.2.14End of Topic Test - Cancer8.2.15A-A* (AO3/4) - Gene Expression & Cancer
8.3Genome Projects
Practice questions on Types of Polysaccharides
Can you answer these? Test yourself with free interactive practice on Seneca — used by over 10 million students.
- 1Which of the following is true of starch?True / false
- 2Where is starch primarily stored in plants?Multiple choice
- 3
- 4Which of the following is true of glycogen?True / false
- 5
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