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DP IB Biology: HL

Revision Notes

Home / IB / Biology: HL / DP / Revision Notes / 6. Human Physiology / 6.4 Gas Exchange / 6.4.3 Lung Diseases


6.4.3 Lung Diseases


Cancer

NOS: Obtain evidence for theories: epidemiological studies have contributed to our understanding of the causes of lung cancer

  • Theories are developed based on evidence collected through observation and where possible, scientific investigations
  • Obtaining valid and reliable evidence for theories on causes and consequences of different diseases can be difficult for several reasons.
    • The sensitive nature of the data required
    • Difficulty finding volunteers with the correct specific diagnoses
    • The effect of confounding factors

  • Epidemiology is the study of disease which includes monitoring the numbers and distribution of cases that arise, as well as building a bigger picture of the potential causes of the disease
  • Epidemiological studies are carried out on large numbers of patient volunteers to give an unbiased and reliable collection of data which make it possible to draw links between certain factors and the development of a disease

Causation and correlation

  • It is very tricky to show that one particular factor is responsible for causing a disease, such as lung cancer, instead, data is usually used to show a correlation between a certain risk factor and the incidence of a disease
  • Confounding factors which share a similar correlation and also imply causation of the disease can make it difficult to establish the actual determinant
    • Therefore it is necessary to study several factors simultaneously to collect enough data to carry out statistical analysis and develop the overall picture

  • Risk factors contribute towards the likelihood of developing a disease
    • Therefore risk factors that are more easily controlled and measured in isolation are more likely to have a proven causal relationship, as they can be investigated in a more scientific manner
    • For example, an individual’s exposure to smoking is much easier to quantify than their exposure to air pollution

  • When analysing data and studies it is always important to remember that risk factors interact with each other
    • For example, a smoker with asthma is likely to suffer the associated negative health side effects more quickly than a smoker without asthma

  • It is always important to remember that even though there is a correlation, this does not mean that there is a direct causal link
    • For example, in places with higher pollution, there may be more asthmatic individuals but this does not mean that pollution caused asthma as there are many other variables at play

Causes of lung cancer

  • Of all the cancers, lung cancer is the most commonly diagnosed and results in the most deaths globally
  • Cancer occurs if mutations affect the regulation of mitosis in cells
  • This causes uncontrolled mitosis which develops into a mass of cells in the lumen of the airways
  • The tumour becomes larger because it has no method of programmed cell death and survives because it develops its own blood supply (vascularisation)
  • The tumour then starts to interfere with the normal working of the lungs, such as by squeezing against blood vessels or cancer cells entering into the lymphatic system, where they may develop another tumour
  • A causal relationship has been proven for some risk factors relating to lung cancer
    • Smoking is a key contributor
      • Tobacco in cigarette smoke has been shown to have mutagenic effects on body cells due to chemicals found in the smoke
      • The effects of these mutagenic chemicals can lead to cancer in smokers as well as the passive smokers inhaling their second hand smoke

    • Inhalation of air pollution similarly, can result in lung cancer
      • In cities, average rates of lung cancer diagnoses are much higher due to high levels of vehicle exhaust fumes and smoke from burning organic matter

    • Radon gas is a radioactive gas which can contribute to the numbers of lung cancer in some areas more than others
      • Radon is released from rocks and buildings made from rocks containing high levels of radon gas

    • Various building materials, such as asbestos and silica, produce small dust particles which can cause lung cancer if they are inhaled
      • There are strict rules about using or working with materials, such as asbestos and silica, to minimise exposure and therefore the associated risks

Consequences of lung cancer

  • There are many symptoms associated with a lung cancer diagnosis, including:
    • Breathing difficulties
    • Coughing, sometimes coughing up blood
    • Chest pains
    • Loss of appetite and weight loss
    • Persistent fatigue
    • Tumours can form in the lungs
    • In severe cases, the primary tumours metastasise and lead to the formation of secondary tumours elsewhere in the body

  • Survival rates from lung cancer are very low compared to other cancer types
    • Only 15% of patients will survive more than 5 years

  • Patients that do survive may suffer from long term symptoms such as:
    • Pain
    • Breathing difficulties
    • Fatigue
    • Anxieties associated with a cancer diagnosis and future prognosis

  • Treatments for lung cancer include:
    • Chemotherapy
    • Radiotherapy
    • Lung removal

Exam Tip

Scatter diagrams are used to identify correlations between two variables to determine the relationships between two factors. For example, between risk factors and certain disease.Correlation can be positive or negative

  • Positive correlation: as variable A increases, variable B increases
  • Negative correlation: as variable A increases, variable B decreases
  • If there is no correlation between variables the correlation coefficient will be 0

Types of correlation graphs, downloadable AS & A Level Biology revision notes

Image showing different types of correlation in scatter graphs

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

Emphysema

Causes of emphysema

  • Emphysema is an example of a Chronic obstructive pulmonary disease (COPD) which also includes lung diseases such as asthma and chronic bronchitis
  • In a healthy lung, some phagocytes are present as part of the non-specific immune response to protect against bacteria found in the lungs
    • Phagocytes produce the protein digesting enzyme, elastase to destroy bacteria
    • Elastase also breaks down proteins in the cells of the lungs, including elastin
    • An enzyme inhibitor, alpha 1-antitrypsin (A1AT), is produced by lung cells to prevent damage caused by elastase

  • In smokers, goblet cells in the ciliated epithelium become enlarged and produce more mucus which destroys the cilia in the trachea and
  • This prevents cilia from sweeping mucus, containing bacteria, dust and other microorganisms away from the lungs, this leads to infections in the lungs
  • Infections attract more phagocytes to the lungs and the phagocytes release elastase
  • A1AT is not effective against the increased levels of elastase and so the enzyme damages the elasticity of the alveolar walls
  • Without enough elastin, the alveoli break down and may burst, creating large air spaces in the alveoli with an insufficient surface area to volume ratio
  • Thickening of the alveolar walls increases the diffusion distance for gas exchange
  • This reduces the efficiency of gas exchange, causing emphysema where less oxygen is carried in blood (making exercise difficult)
  • Once the disease progresses, people often need a constant supply of oxygen to stay alive

Consequences of emphysema

  • Damage to the alveoli which result in emphysema, is irreversible
  • It leads to low blood oxygen levels and high carbon dioxide levels in patients
  • The resultant symptoms include
    • Shortness of breath or laboured ventilation
    • A chronic or persistent cough
    • Chest tightness
    • Wheezing and difficulty breathing when exercising or during any physical activity
    • Lack of energy

Emphysema in the lungs, IGCSE & GCSE Biology revision notes

Emphysema can lead to a reduced number of alveolar air sacs with thicker walls



  • 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
                                                                                                                                                                                                                                                                                                                                                                                                                                                                                          Ruth Brindle

                                                                                                                                                                                                                                                                                                                                                                                                                                                                                          Author: Ruth

                                                                                                                                                                                                                                                                                                                                                                                                                                                                                          Ruth graduated from Sheffield University with a degree in Biology and went on to teach Science in London whilst also completing an MA in innovation in Education. With 10 years of teaching experience across the 3 key science disciplines, Ruth decided to set up a tutoring business to support students in her local area. Ruth has worked with several exam boards and loves to use her experience to produce educational materials which make the mark schemes accessible to all students.


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