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DP IB Biology: HL

Revision Notes

Home / IB / Biology: HL / DP / Revision Notes / 2. Molecular Biology / 2.2 Carbohydrates & Lipids / 2.2.2 Fatty Acids


2.2.2 Fatty Acids


Fatty Acids: Types

  • Triglycerides are a form of lipid, made up of one molecule of glycerol with three fatty acids attached to it
  • These fatty acids have long hydrocarbon ‘tails’
  • Fatty acids occur in two forms:
    • Saturated fatty acids
    • Unsaturated fatty acids
      • Unsaturated fatty acids can be monounsaturated or polyunsaturated
  • The difference between these fatty acid types is found in their hydrocarbon tails
  • Saturated fatty acids

    • In saturated fatty acids, the bonds between the carbon atoms in the hydrocarbon tail are all single bonds
    • The fatty acid is said to be ‘saturated’ with hydrogen
      • This means that each carbon atom in the hydrocarbon tail (except for the final carbon atom) is bonded to two hydrogen atoms

    • Saturated fatty acids can be synthesised industrially by hydrogenation (reaction with hydrogen gas) of unsaturated fatty acids
    • All the carbon-to-carbon bonds are single bonds in saturated fatty acids

    [Saturated fatty acid example.png], downloadable AS & A Level Biology revision notes

    An example of a saturated fatty acid

    Unsaturated fatty acids

    • In unsaturated fatty acids, the bonds between the carbon atoms in the hydrocarbon tail are not all single bonds
      • There is at least one carbon-carbon double bond; a fatty acid with one C=C double bond is known as monounsaturated fatty acid

      • In some unsaturated fatty acids, there are many carbon-carbon double bonds; these are known as polyunsaturated fatty acids
      • These double bonds can cause the hydrocarbon tail of unsaturated fatty acids to kink (bend slightly), meaning they are not as straight as saturated fatty acids

    • The fatty acid is said to be ‘unsaturated’ because the hydrocarbon tail does not contain the maximum number of hydrogen atoms possible
      • This is because each carbon atom in a carbon-carbon double bond can only bond to one hydrogen atom (instead of two)

    Unsaturated fatty acid example, downloadable AS & A Level Biology revision notes

    An example of a monounsaturated fatty acid

    Triglycerides_Basics - types of fatty acids (2), downloadable AS & A Level Biology revision notes

    An example of a polyunsaturated fatty acid

    Exam Tip

    You don't need to know the names of various fatty acids, but you should be able to recognise from a diagram whether a fatty acid is saturated, monounsaturated or polyunsaturated (look for any carbon-carbon double bonds)!

    Unsaturated Fatty Acids

    The different isomers of unsaturated fatty acids

    • A single C-C bond in a hydrocarbon chain is able to rotate along its axis so that rotation of one part of the molecule in relation to others is possible
    • The rotation may cause conformational changes in molecules but they all remain identical
    • However, when there is a C=C double bond in a hydrocarbon chain, no rotation is possible
    • This causes isomers of fatty acids to be formed, each with different properties
    • The isomers are labelled cis and trans isomers

    Cis-isomers

    • At a C=C double bond, the attached hydrogen atoms are on the same side of the hydrocarbon chain as each other
      • This causes a kink in the fatty acid chain which means the fatty acid chains are less tightly packed together, lowering their melting point (less kinetic energy is needed to break them apart)
      • Triglycerides that contain cis-unsaturated fatty acids are liquid (oils) at room temperature

    Cis- Fatty Acid Structure, downloadable IB Biology revision notes

    The Structural Differences Between a Saturated and a Cis-Unsaturated Fatty Acid

    Trans-isomers

    • At a C=C double bond, the attached hydrogen atoms are on the opposite sides of the hydrocarbon chain to each other
      • The lack of bend in the hydrocarbon chain allows them to pack more closely together meaning they have a higher melting point (this property makes them more attractive to food manufacturers)
      • Triglycerides that contain trans-saturated fatty acids are solid are room temperature

    Trans- Fatty Acid Structure, downloadable IB Biology revision notes

    The Structure of a Trans-Unsaturated Fatty Acid

    Fatty Acids: Health Risks

    The use of trans-fatty acids in the food industry

    • Trans-fatty acids occur in small quantities in natural products such as dairy and red meat
    • Artificial trans-fats (which contain trans-fatty acids) are made industrially by the hydrogenation of liquid vegetable oils
    • Trans-fats are favoured by food manufacturers for commercial reasons
      • They are more solid at room temperature
      • They create more stable emulsions in shortening agents
      • Food products with trans-fats appear (in their retail packaging) drier and less 'greasy' to consumers
      • Alleged taste benefits (though this is subjective)
      • They can be reused more times eg. in large-scale deep-fat fryers
      • Many countries have legislated to restrict the use of trans-fats in the foodservice industry

    • Many foods that contains trans-fats (often labelled as 'partially hydrogenated vegetable oils') are sold as processed products in supermarkets
      • Biscuits/cookies
      • Cakes
      • Doughnuts
      • Pie crusts
      • Crisps
      • Pizza bases
      • Certain kinds of margarine and spreads

    Trans-fatty acids have associated health risks

    • The two types of fat that lead to health problems are namely saturated fats and trans-fats
      • Doctors recommend limiting your intake of these types of fats
    • Trans-fats alter the balance of various types of cholesterol
      • They increase low-density lipoprotein (LDL) levels in circulation (so-called 'bad' cholesterol)
      • They decrease high-density lipoprotein (HDL) levels in circulation (so-called 'good' cholesterol)
    • LDLs are known to increase the risk of coronary heart disease, blood clotting and strokes
    • Doctors recommend that the bulk of fats intake should come from monounsaturated fats, which reduce LDL levels
      • Omega-3 fats and oils are a well-publicised source of monounsaturated fats; these are found in fish, pulses and certain nuts

    Buildup of plaque in the coronary arteries, IGCSE & GCSE Biology revision notesExcess consumption of trans-fatty acids and saturated fats can lead to the buildup of cholesterol and the blockage of coronary arteries, causing Coronary Heart Disease (CHD)

    Evaluating claims

    • Evidence for the claims surrounding the health risks associated with trans-fats often comes from 'cohort studies'
      • Eg. Greenland Eskimos, whose diet is rich in oily fish and meat, have a very low incidence of heart disease
    • Other epidemiological studies can establish correlations between diet and incidence of disease
    • Whilst it is rare to find a direct causal link between fat intake and heart disease, the many claims about fats suggest strongly that trans-fats have an overall detrimental effect on health when consumed in high quantities
    • Other conditions linked to trans-fats include
      • Allergy
      • Breast cancer
      • Colonic cancer
      • Cardiovascular diseases
      • Premature birth
      • Preeclampsia (a condition associated with pregnancy)
      • Disorders of the nervous system
      • Vision defects in infants
      • Diabetes
      • Obesity

    Exam Tip

    • It is important to remember that correlation does not always mean causation
      • Correlation is an association or relationship between variables
      • Causation occurs when one variable has an influence or is influenced by, another
      • There is a clear distinction between correlation and causation: a correlation does not necessarily imply a causative relationship



    • 1. Cell Biology
      • 1.1 Cells: Theory
        • 1.1.1 Cell Theory
          • 1.1.2 Functions of Life
            • 1.1.3 Surface Area to Volume Ratio
              • 1.1.4 Cell Specialisation
                • 1.1.5 Stem Cells
                  • 1.1.6 Skills: Cell Theory
                  • 1.2 Cells: Origin & Ultrastructure
                    • 1.2.1 Origin of Cells
                      • 1.2.2 Endosymbiotic Theory
                        • 1.2.3 Prokaryotic Cell Structure
                          • 1.2.4 Eukaryotic Cell Structure
                            • 1.2.5 Exocrine Pancreatic & Palisade Mesophyll Cells
                              • 1.2.6 Comparison of Prokaryotic & Eukaryotic Cells
                                • 1.2.7 Microscopes
                                  • 1.2.8 Skills: Drawing Cells
                                    • 1.2.9 Skills: Cell Origin & Ultrastructure
                                    • 1.3 Cells: Membrane Structure & Transport
                                      • 1.3.1 Phospholipid Bilayer Properties
                                        • 1.3.2 Membrane Proteins
                                          • 1.3.3 History of Fluid Mosaic Model
                                            • 1.3.4 Membrane Transport
                                              • 1.3.5 Active Transport & Bulk Transport
                                                • 1.3.6 Skills: Membrane Structure & Transport
                                                  • 1.3.7 Skills: Estimation of Osmolarity
                                                  • 1.4 Cells: Division
                                                    • 1.4.1 Cell Cycle
                                                      • 1.4.2 Phases of Mitosis
                                                        • 1.4.3 Cancer
                                                          • 1.4.4 Skills: Cell Division
                                                        • 2. Molecular Biology
                                                          • 2.1 Metabolism & Water
                                                            • 2.1.1 Molecules
                                                              • 2.1.2 Metabolism
                                                                • 2.1.3 Hydrogen Bonds
                                                                  • 2.1.4 Water
                                                                  • 2.2 Carbohydrates & Lipids
                                                                    • 2.2.1 Carbohydrates
                                                                      • 2.2.2 Fatty Acids
                                                                        • 2.2.3 Lipids
                                                                          • 2.2.4 Skills: Visualising Carbohydrates
                                                                            • 2.2.5 Skills: Calculating BMI
                                                                            • 2.3 Proteins
                                                                              • 2.3.1 Proteins
                                                                                • 2.3.2 Protein Structure & Function
                                                                                  • 2.3.3 The Variety of Proteins
                                                                                    • 2.3.4 Skills: Molecules
                                                                                    • 2.4 Enzymes
                                                                                      • 2.4.1 Enzymes
                                                                                        • 2.4.2 Immobilised Enzymes
                                                                                          • 2.4.3 Skills: Enzyme Experiments
                                                                                          • 2.5 Nucleic Acids: Structure & DNA Replication
                                                                                            • 2.5.1 DNA & RNA Structure
                                                                                              • 2.5.2 DNA Replication
                                                                                                • 2.5.3 Skills: DNA Replication
                                                                                                • 2.6 Transcription & Translation
                                                                                                  • 2.6.1 Transcription
                                                                                                    • 2.6.2 Translation
                                                                                                      • 2.6.3 Biotechnology
                                                                                                        • 2.6.4 Skills: DNA, RNA & Protein Synthesis
                                                                                                          • 2.6.5 Skills: Interpreting Sequences
                                                                                                          • 2.7 Cellular Respiration
                                                                                                            • 2.7.1 Cellular Respiration
                                                                                                              • 2.7.2 Anaerobic Respiration
                                                                                                                • 2.7.3 Aerobic Respiration
                                                                                                                  • 2.7.4 Skills: Respiration
                                                                                                                  • 2.8 Photosynthesis
                                                                                                                    • 2.8.1 Photosynthesis
                                                                                                                      • 2.8.2 Photosynthesis Continued
                                                                                                                        • 2.8.3 Skills: Photosynthesis
                                                                                                                          • 2.8.4 Skills: Separating Photosynthetic Pigments
                                                                                                                        • 3. Genetics
                                                                                                                          • 3.1 Genes & Chromosomes
                                                                                                                            • 3.1.1 Genes
                                                                                                                              • 3.1.2 Alleles
                                                                                                                                • 3.1.3 Mutation
                                                                                                                                  • 3.1.4 Genome
                                                                                                                                    • 3.1.5 Prokaryotic Chromosomes
                                                                                                                                      • 3.1.6 Eukaryotic Chromosomes
                                                                                                                                        • 3.1.7 Chromosome Number
                                                                                                                                          • 3.1.8 Sex Determination
                                                                                                                                            • 3.1.9 Karyograms
                                                                                                                                              • 3.1.10 Skills: Using Databases
                                                                                                                                              • 3.2 Meiosis
                                                                                                                                                • 3.2.1 Meiosis
                                                                                                                                                  • 3.2.2 Stages of Meiosis
                                                                                                                                                    • 3.2.3 Genetic Variation
                                                                                                                                                      • 3.2.4 Non-disjunction
                                                                                                                                                        • 3.2.5 Skills: Meiosis
                                                                                                                                                        • 3.3 Inheritance
                                                                                                                                                          • 3.3.1 Inheritance
                                                                                                                                                            • 3.3.2 Inheriting Alleles
                                                                                                                                                              • 3.3.3 Skills: Inheritance
                                                                                                                                                                • 3.3.4 Inheritance of Genetic Diseases
                                                                                                                                                                  • 3.3.5 Mutations & Disease
                                                                                                                                                                  • 3.4 Genetic Modification & Biotechnology
                                                                                                                                                                    • 3.4.1 Electrophoresis & PCR
                                                                                                                                                                      • 3.4.2 DNA Profiling
                                                                                                                                                                        • 3.4.3 Genetic Modification
                                                                                                                                                                          • 3.4.4 Cloning
                                                                                                                                                                            • 3.4.5 Skills: Genetic Modification & Biotechnology
                                                                                                                                                                          • 4. Ecology
                                                                                                                                                                            • 4.1 Species, Communities, Ecosystems & Energy Flow
                                                                                                                                                                              • 4.1.1 Species & Population
                                                                                                                                                                                • 4.1.2 Methods of Nutrition
                                                                                                                                                                                  • 4.1.3 Community
                                                                                                                                                                                    • 4.1.4 Nutrient Cycling
                                                                                                                                                                                      • 4.1.5 Energy Flow
                                                                                                                                                                                        • 4.1.6 Energy Losses
                                                                                                                                                                                          • 4.1.7 Skills: Species, Communities, Ecosystems & Energy Flow
                                                                                                                                                                                            • 4.1.8 Skills: Chi-squared test & Statistical Significance
                                                                                                                                                                                              • 4.1.9 Skills: Pyramids of Energy
                                                                                                                                                                                              • 4.2 Carbon Cycling & Climate Change
                                                                                                                                                                                                • 4.2.1 Carbon Cycle: Carbon Dioxide
                                                                                                                                                                                                  • 4.2.2 Carbon Cycle: Carbon Dioxide in the Atmosphere
                                                                                                                                                                                                    • 4.2.3 Carbon Cycle: Methane
                                                                                                                                                                                                      • 4.2.4 Carbon Cycle: Organic Matter
                                                                                                                                                                                                        • 4.2.5 Climate Change: Greenhouse Effect
                                                                                                                                                                                                          • 4.2.6 Climate Change: Impact
                                                                                                                                                                                                            • 4.2.7 Climate Change: Causes
                                                                                                                                                                                                              • 4.2.8 Skills: Carbon Cycling & Climate Change
                                                                                                                                                                                                            • 5. Evolution and Biodiversity
                                                                                                                                                                                                              • 5.1 Evolution & Natural Selection
                                                                                                                                                                                                                • 5.1.1 Evolution
                                                                                                                                                                                                                  • 5.1.2 Evolution: Evidence
                                                                                                                                                                                                                    • 5.1.3 Variation
                                                                                                                                                                                                                      • 5.1.4 Natural Selection
                                                                                                                                                                                                                        • 5.1.5 Natural Selection Examples
                                                                                                                                                                                                                        • 5.2 Classification & Cladistics
                                                                                                                                                                                                                          • 5.2.1 Classification System
                                                                                                                                                                                                                            • 5.2.2 Classifying Organisms
                                                                                                                                                                                                                              • 5.2.3 Plant Phyla Features
                                                                                                                                                                                                                                • 5.2.4 Animal Phyla Features
                                                                                                                                                                                                                                  • 5.2.5 Cladistics
                                                                                                                                                                                                                                    • 5.2.6 Reclassification
                                                                                                                                                                                                                                      • 5.2.7 Skills: Classification & Cladistics
                                                                                                                                                                                                                                    • 6. Human Physiology
                                                                                                                                                                                                                                      • 6.1 Digestion & Absorption
                                                                                                                                                                                                                                        • 6.1.1 Digestion
                                                                                                                                                                                                                                          • 6.1.2 Villi & Absorption
                                                                                                                                                                                                                                            • 6.1.3 Absorption
                                                                                                                                                                                                                                              • 6.1.4 Skills: Digestion & Absorption
                                                                                                                                                                                                                                              • 6.2 The Blood System
                                                                                                                                                                                                                                                • 6.2.1 The Blood System: History
                                                                                                                                                                                                                                                  • 6.2.2 The Blood System: Vessels
                                                                                                                                                                                                                                                    • 6.2.3 The Blood System: Double Circulation
                                                                                                                                                                                                                                                      • 6.2.4 The Blood System: Cardiac Cycle
                                                                                                                                                                                                                                                        • 6.2.5 The Heart Rate
                                                                                                                                                                                                                                                          • 6.2.6 Skills: The Blood System
                                                                                                                                                                                                                                                          • 6.3 Defence Against Infectious Disease
                                                                                                                                                                                                                                                            • 6.3.1 Skin
                                                                                                                                                                                                                                                              • 6.3.2 Blood Clotting
                                                                                                                                                                                                                                                                • 6.3.3 White Blood Cells
                                                                                                                                                                                                                                                                  • 6.3.4 Antibiotics
                                                                                                                                                                                                                                                                    • 6.3.5 Antibiotic Resistance
                                                                                                                                                                                                                                                                    • 6.4 Gas Exchange
                                                                                                                                                                                                                                                                      • 6.4.1 Ventilation: Function & Structures
                                                                                                                                                                                                                                                                        • 6.4.2 Ventilation: Mechanism
                                                                                                                                                                                                                                                                          • 6.4.3 Lung Diseases
                                                                                                                                                                                                                                                                            • 6.4.4 Skills: Monitoring Ventilation
                                                                                                                                                                                                                                                                            • 6.5 Neurones & Synapses
                                                                                                                                                                                                                                                                              • 6.5.1 Neurones: Function & Structure
                                                                                                                                                                                                                                                                                • 6.5.2 Nerve Impulses
                                                                                                                                                                                                                                                                                  • 6.5.3 Synapses
                                                                                                                                                                                                                                                                                    • 6.5.4 Skill: Neurones & Synapses
                                                                                                                                                                                                                                                                                    • 6.6 Hormones, Homeostasis & Reproduction
                                                                                                                                                                                                                                                                                      • 6.6.1 Hormones
                                                                                                                                                                                                                                                                                        • 6.6.2 Hormones Continued
                                                                                                                                                                                                                                                                                          • 6.6.3 Reproduction: Background
                                                                                                                                                                                                                                                                                            • 6.6.4 Reproduction: Sex Determination in Males
                                                                                                                                                                                                                                                                                              • 6.6.5 Reproduction: Sex Determination in Females
                                                                                                                                                                                                                                                                                                • 6.6.6 Skills: Reproduction Diagrams
                                                                                                                                                                                                                                                                                              • 7. Nucleic Acids (HL Only)
                                                                                                                                                                                                                                                                                                • 7.1 DNA Structure & Replication
                                                                                                                                                                                                                                                                                                  • 7.1.1 DNA Structure
                                                                                                                                                                                                                                                                                                    • 7.1.2 Mechanism of DNA Replication
                                                                                                                                                                                                                                                                                                      • 7.1.3 Non-coding DNA
                                                                                                                                                                                                                                                                                                        • 7.1.4 DNA Sequencing
                                                                                                                                                                                                                                                                                                          • 7.1.5 Skills: The Hershey & Chase Experiment
                                                                                                                                                                                                                                                                                                            • 7.1.6 Skills: Nucleosomes & Molecular Visualisation Software
                                                                                                                                                                                                                                                                                                            • 7.2 Transcription & Gene Expression
                                                                                                                                                                                                                                                                                                              • 7.2.1 Regulation of Gene Expression by Proteins
                                                                                                                                                                                                                                                                                                                • 7.2.2 Environment & Gene Expression
                                                                                                                                                                                                                                                                                                                  • 7.2.3 Transcription
                                                                                                                                                                                                                                                                                                                    • 7.2.4 Post-transcriptional Modification
                                                                                                                                                                                                                                                                                                                      • 7.2.5 Skills: Analysing DNA Methylation Patterns
                                                                                                                                                                                                                                                                                                                      • 7.3 Translation
                                                                                                                                                                                                                                                                                                                        • 7.3.1 Translation
                                                                                                                                                                                                                                                                                                                          • 7.3.2 Ribosomes
                                                                                                                                                                                                                                                                                                                            • 7.3.3 Translation in Prokaryotes
                                                                                                                                                                                                                                                                                                                              • 7.3.4 Bioinformatics
                                                                                                                                                                                                                                                                                                                                • 7.3.5 Levels of Protein Structure
                                                                                                                                                                                                                                                                                                                                  • 7.3.6 Skills: Polysomes & Ribosomes
                                                                                                                                                                                                                                                                                                                                • 8. Metabolism, Cell Respiration & Photosynthesis (HL Only)
                                                                                                                                                                                                                                                                                                                                  • 8.1 Metabolism
                                                                                                                                                                                                                                                                                                                                    • 8.1.1 Metabolic Pathways
                                                                                                                                                                                                                                                                                                                                      • 8.1.2 Inhibition
                                                                                                                                                                                                                                                                                                                                        • 8.1.3 Bioinformatics & Metabolism
                                                                                                                                                                                                                                                                                                                                          • 8.1.4 Skills: Rates of Reaction & Types of Inhibition
                                                                                                                                                                                                                                                                                                                                          • 8.2 Cell Respiration
                                                                                                                                                                                                                                                                                                                                            • 8.2.1 Oxidation, Reduction & Phosphorylation
                                                                                                                                                                                                                                                                                                                                              • 8.2.2 Overview of the Stages of Respiration
                                                                                                                                                                                                                                                                                                                                                • 8.2.3 Glycolysis
                                                                                                                                                                                                                                                                                                                                                  • 8.2.4 The Link Reaction & The Krebs Cycle
                                                                                                                                                                                                                                                                                                                                                    • 8.2.5 Oxidative Phosphorylation
                                                                                                                                                                                                                                                                                                                                                      • 8.2.6 Mitochondria
                                                                                                                                                                                                                                                                                                                                                        • 8.2.7 Skills: Cell Respiration
                                                                                                                                                                                                                                                                                                                                                        • 8.3 Photosynthesis
                                                                                                                                                                                                                                                                                                                                                          • 8.3.1 Light-dependent Reactions
                                                                                                                                                                                                                                                                                                                                                            • 8.3.2 Photophosphorylation
                                                                                                                                                                                                                                                                                                                                                              • 8.3.3 Light-independent Reactions
                                                                                                                                                                                                                                                                                                                                                                • 8.3.4 Investigating Carbon Fixation in Photosynthesis
                                                                                                                                                                                                                                                                                                                                                                  • 8.3.5 Chloroplast
                                                                                                                                                                                                                                                                                                                                                                    • 8.3.6 Skills: Photosynthesis
                                                                                                                                                                                                                                                                                                                                                                  • 9. Plant Biology (HL Only)
                                                                                                                                                                                                                                                                                                                                                                    • 9.1 Transport in the Xylem of Plants
                                                                                                                                                                                                                                                                                                                                                                      • 9.1.1 Transpiration in Plants
                                                                                                                                                                                                                                                                                                                                                                        • 9.1.2 The Transpiration Stream
                                                                                                                                                                                                                                                                                                                                                                          • 9.1.3 The Roots & Water Transport
                                                                                                                                                                                                                                                                                                                                                                            • 9.1.4 Adaptations of Xerophytes
                                                                                                                                                                                                                                                                                                                                                                              • 9.1.5 Skills: Drawing Xylem Vessels
                                                                                                                                                                                                                                                                                                                                                                                • 9.1.6 Skills: Experiments Investigating the Rate of Transpiration
                                                                                                                                                                                                                                                                                                                                                                                • 9.2 Transport in the Phloem of Plants
                                                                                                                                                                                                                                                                                                                                                                                  • 9.2.1 Translocation in Plants
                                                                                                                                                                                                                                                                                                                                                                                    • 9.2.2 Sucrose Loading
                                                                                                                                                                                                                                                                                                                                                                                      • 9.2.3 Hydrostatic Pressure Gradients
                                                                                                                                                                                                                                                                                                                                                                                        • 9.2.4 Skills: Identifying Xylem & Phloem
                                                                                                                                                                                                                                                                                                                                                                                          • 9.2.5 Skills: Measuring Phloem Transport Rates
                                                                                                                                                                                                                                                                                                                                                                                          • 9.3 Growth in Plants
                                                                                                                                                                                                                                                                                                                                                                                            • 9.3.1 Plant Growth
                                                                                                                                                                                                                                                                                                                                                                                              • 9.3.2 Plant Hormones
                                                                                                                                                                                                                                                                                                                                                                                                • 9.3.3 Micropropagation
                                                                                                                                                                                                                                                                                                                                                                                                • 9.4 Reproduction in Plants
                                                                                                                                                                                                                                                                                                                                                                                                  • 9.4.1 Flowering
                                                                                                                                                                                                                                                                                                                                                                                                    • 9.4.2 Plant Reproduction
                                                                                                                                                                                                                                                                                                                                                                                                      • 9.4.3 Skills: Drawing Plant Structures
                                                                                                                                                                                                                                                                                                                                                                                                        • 9.4.4 Skills: Investigating Factors Affecting Germination
                                                                                                                                                                                                                                                                                                                                                                                                      • 10. Genetics & Evolution (HL Only)
                                                                                                                                                                                                                                                                                                                                                                                                        • 10.1 Meiosis
                                                                                                                                                                                                                                                                                                                                                                                                          • 10.1.1 The Process of Meiosis
                                                                                                                                                                                                                                                                                                                                                                                                            • 10.1.2 Crossing Over
                                                                                                                                                                                                                                                                                                                                                                                                              • 10.1.3 Meiosis I
                                                                                                                                                                                                                                                                                                                                                                                                                • 10.1.4 Meiosis II
                                                                                                                                                                                                                                                                                                                                                                                                                  • 10.1.5 Skills: Drawing Chiasmata
                                                                                                                                                                                                                                                                                                                                                                                                                  • 10.2 Inheritance
                                                                                                                                                                                                                                                                                                                                                                                                                    • 10.2.1 Unlinked Genes
                                                                                                                                                                                                                                                                                                                                                                                                                      • 10.2.2 Skills: Analysing Dihybrid Crosses
                                                                                                                                                                                                                                                                                                                                                                                                                        • 10.2.3 Gene Linkage
                                                                                                                                                                                                                                                                                                                                                                                                                          • 10.2.4 Skills: Identifying Recombinants
                                                                                                                                                                                                                                                                                                                                                                                                                            • 10.2.5 Skills: Chi-squared Test
                                                                                                                                                                                                                                                                                                                                                                                                                              • 10.2.6 Variation
                                                                                                                                                                                                                                                                                                                                                                                                                              • 10.3 Gene Pools & Speciation
                                                                                                                                                                                                                                                                                                                                                                                                                                • 10.3.1 Gene Pools
                                                                                                                                                                                                                                                                                                                                                                                                                                  • 10.3.2 Evolution
                                                                                                                                                                                                                                                                                                                                                                                                                                    • 10.3.3 Speciation
                                                                                                                                                                                                                                                                                                                                                                                                                                      • 10.3.4 Polyploidy & Speciation
                                                                                                                                                                                                                                                                                                                                                                                                                                        • 10.3.5 Skills: Comparing Allele Frequencies Between Populations
                                                                                                                                                                                                                                                                                                                                                                                                                                      • 11. Animal Physiology (HL Only)
                                                                                                                                                                                                                                                                                                                                                                                                                                        • 11.1 Antibody Production & Vaccination
                                                                                                                                                                                                                                                                                                                                                                                                                                          • 11.1.1 Antigens
                                                                                                                                                                                                                                                                                                                                                                                                                                            • 11.1.2 Specific Immune Response
                                                                                                                                                                                                                                                                                                                                                                                                                                              • 11.1.3 Antibodies, Vaccines & Immunity
                                                                                                                                                                                                                                                                                                                                                                                                                                                • 11.1.4 Smallpox Vaccine & Eradication
                                                                                                                                                                                                                                                                                                                                                                                                                                                  • 11.1.5 Zoonosis
                                                                                                                                                                                                                                                                                                                                                                                                                                                    • 11.1.6 Histamines
                                                                                                                                                                                                                                                                                                                                                                                                                                                      • 11.1.7 Monoclonal Antibodies
                                                                                                                                                                                                                                                                                                                                                                                                                                                        • 11.1.8 Skills: Analysing Epidemiological Data
                                                                                                                                                                                                                                                                                                                                                                                                                                                        • 11.2 Movement
                                                                                                                                                                                                                                                                                                                                                                                                                                                          • 11.2.1 Requirements for Movement
                                                                                                                                                                                                                                                                                                                                                                                                                                                            • 11.2.2 Skeletal Muscle
                                                                                                                                                                                                                                                                                                                                                                                                                                                              • 11.2.3 Mechanism of Muscle Contraction
                                                                                                                                                                                                                                                                                                                                                                                                                                                                • 11.2.4 Skills: The Human Elbow & Sarcomeres
                                                                                                                                                                                                                                                                                                                                                                                                                                                                  • 11.2.5 Skills: Analysing Muscle Contractions in Electron Micrographs
                                                                                                                                                                                                                                                                                                                                                                                                                                                                  • 11.3 The Kidney & Osmoregulation
                                                                                                                                                                                                                                                                                                                                                                                                                                                                    • 11.3.1 Osmoregulation in Organisms
                                                                                                                                                                                                                                                                                                                                                                                                                                                                      • 11.3.2 Kidney: Structure & Function
                                                                                                                                                                                                                                                                                                                                                                                                                                                                        • 11.3.3 Conserving Water
                                                                                                                                                                                                                                                                                                                                                                                                                                                                          • 11.3.4 The Role of ADH
                                                                                                                                                                                                                                                                                                                                                                                                                                                                            • 11.3.5 Types of Nitrogenous Waste
                                                                                                                                                                                                                                                                                                                                                                                                                                                                              • 11.3.6 Kidney Failure & Urinalysis
                                                                                                                                                                                                                                                                                                                                                                                                                                                                                • 11.3.7 Skills: Drawing & Annotating the Kidney
                                                                                                                                                                                                                                                                                                                                                                                                                                                                                • 11.4 Sexual Reproduction
                                                                                                                                                                                                                                                                                                                                                                                                                                                                                  • 11.4.1 Oogenesis & Spermatogenesis
                                                                                                                                                                                                                                                                                                                                                                                                                                                                                    • 11.4.2 Fertilisation
                                                                                                                                                                                                                                                                                                                                                                                                                                                                                      • 11.4.3 Pregnancy
                                                                                                                                                                                                                                                                                                                                                                                                                                                                                        • 11.4.4 Hormones in Pregnancy
                                                                                                                                                                                                                                                                                                                                                                                                                                                                                          • 11.4.5 The Placenta
                                                                                                                                                                                                                                                                                                                                                                                                                                                                                            • 11.4.6 Oestrogen Pollution
                                                                                                                                                                                                                                                                                                                                                                                                                                                                                              • 11.4.7 Skills: Annotating Sexual Reproduction Diagrams
                                                                                                                                                                                                                                                                                                                                                                                                                                                                                            Phil Chatterton

                                                                                                                                                                                                                                                                                                                                                                                                                                                                                            Author: Phil

                                                                                                                                                                                                                                                                                                                                                                                                                                                                                            Phil graduated in Biochemistry from Birmingham University and spent seventeen years in the drinks and chemicals industries. He holds an MBA from Manchester Business School. More recently, Phil has taught in secondary schools, examined GCSE Biology and has also co-directed a tuition agency. He is a passionate believer in promoting numeracy in his teaching and loves to create innovative resources.


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