IB Biology Study Guide and Notes for SL/HL (2020-2021)

IB Biology Detailed Topic-Wise Study Notes

Excellent Study Notes for IB DP Biology Prepared by Subject Matter Experts.

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Topic 1: Cell biology

  • 1.1 Introduction to cells
    • Cell Theory
    • Functions of Life
    • SA : Vol Ratio
    • Magnification
    • Emergent Properties
    • Cell Differentiation
    • Stem Cells
    • Stem Cell Therapy
    • Cell Theory History
    • Microscopes
    • Cell Scale
  • 1.2 Ultrastructure of cells
    • Prokaryotic Cells
    • Eukaryotic Cells
    • Organelles
    • Microscopy
    • Cell Micrographs
    • Types of Bacteria
    • Animal versus Plant Cells
  • 1.3 Membrane structure
    • Phospholipid Bilayer
    • Membrane Proteins
    • Cholesterol
    • Fluid-Mosaic Model
    • Membrane Models
    • Phospholipids
    • Membrane Fluidity
    • Extracellular Matrix
  • 1.4 Membrane transport
    • Types of Transport
    • Simple Diffusion
    • Osmosis
    • Osmolarity
    • Facilitated Diffusion
    • Active Transport
    • Vesicular Transport
    • Bulk Transport
    • Cotransport
    • Kidney Dialysis
  • 1.5 The origin of cells
    • Non-living Synthesis
    • Biogenesis
    • Endosymbiosis
    • Origins of Life
    • RNA World Hypothesis
    • Oxygen Enrichment
  • 1.6 Cell division
    • Cell Cycle
    • Interphase
    • DNA Supercoiling
    • Mitosis
    • Cytokinesis
    • Mitotic Index
    • Cyclins
    • Cancer Development
    • Smoking and Cancer
    • Cell Checkpoints
    • Cell Death

Topic 2: Molecular biology

  • 2.1 Molecules to metabolism
    • Molecular Biology
    • Organic Compounds
    • Organic Subunits -glucose, ribose and fatty  and amino acids
    • Organic Polymers -sugars and lipids
    • Falsifying Vitalism
    • Metabolism
    • Anabolism and Catabolism
    • Periodic Table
    • Types of Bonding
    • Trace Elements
  • 2.2 Water
    • Water Structure
    • Hydrogen Bonding
    • Thermal Properties
    • Cohesive and Adhesive Properties
    • Solvent Properties
    • Significance of Water
    • Water Cycle
  • 2.3 Carbohydrates and lipids
    • Sugar Subunits
    • Sugar Polymers
    • Types of Fatty Acids
    • Triglycerides
    • Lipid Health Risks
    • Sugars versus Lipids
    • Body Mass Index
    • Functions of Lipids
    • Lipoproteins
    • Lipid Absorption
  • 2.4 Proteins
    • Amino Acids
    • Peptide Bonds
    • Protein Structure
    • Denaturation
    • Gene ⇒ Polypeptide
    • Proteome
    • Protein Functions
    • The pH Scale
    • Fibrous vs Globular Proteins
    • Amino Acid Polarity
  • 2.5 Enzymes
    • Enzyme & Substrate
    • Enzyme Catalysis
    • Enzyme Specificity
    • Enzyme Activity
    • Enzyme Experiments
    • Enzymes in Industry
    • Models of Action
    • Types of Enzymes
    • Lactose Intolerance
  • 2.6 Structure of DNA and RNA
    • Nucleotides
    • DNA versus RNA
    • DNA Structure
    • Watson & Crick
    • Nitrogenous Bases
    • Types of RNA
  • 2.7 DNA replication, transcription and translation
    • Semi-Conservative
    • DNA Replication
    • polymerase chain reaction
    • Transcription
    • Genetic Code
    • Translation
    • Universality
    • Sequence Decoding
    • Central Dogma
    • Translation Analogy
    • Degeneracy
    • Point Mutations
  • 2.8 Cell respiration
    • ATP Production
    • Anaerobic Respiration
    • Aerobic Respiration
    • Yeast Fermentation
    • Respirometry
    • Energy Sources
    • Uses of ATP
    • Anaerobic vs Aerobic
  • 2.9 Photosynthesis
    • Photosynthesis
    • Light Spectrum
    • Chlorophyll
    • Action Spectrum
    • Photosynthetic Reactions
    • Chromatographs
    • Limiting Factors
    • Oxygenation of Earth
    • Chloroplasts
    • Chloroplasts

Topic 3: Genetics

  • 3.1 Genes
    • Genes and Loci
    • Alleles
    • Mutations
    • Genome
    • Gene Comparisons
    • Types of Mutations
    • Sickle Cell versus Malaria
    • Genome Structure
    • Pseudogenes

  • 3.2 Chromosomes
    • Prokaryotic Genetics
    • Eukaryote Genetics
    • Identifying Genes
    • Homologous Pairs
    • Diploid versus Haploid
    • Autosome versus Heterosome
    • Karyograms
    • Chromosome Size
    • Chromosome Number
    • Genome Size
    • Prokaryotic vs Eukaryotic DNA
    • Chromosome Types
    • Block Mutations
    • Sex Determination
  • 3.3 Meiosis
    • Meiotic Division
    • Sister Chromatids
    • Stages of Meiosis
    • Crossing Over
    • Random Assortment
    • Sexual Life Cycle
    • Genetic Variation
    • Non-Disjunction
    • Karyotyping
    • Drawing Meiosis
    • Mitosis versus Meiosis
    • Somatic vs Germline Mutations
    • Polyploidy
  • 3.4 Inheritance
    • Mendel’s Laws
    • Haploid Gametes
    • Types of Zygosity
    • Modes of Inheritance
    • Punnett Grids
    • Sex Linked Genes
    • Gene Mutation Rates
    • Pedigree Charts
    • Role of Environment
    • Lethal Alleles
    • Epistasis
    • Pleiotropy
    • X-Inactivation
    • Mosaicism
  • 3.5 Genetic modification and biotechnology
    • polymerase chain reaction
    • Gel Electrophoresis
    • DNA Profiling
    • Gene Transfer
    • GMO Debate
    • Clones
    • Natural Cloning
    • Artificial Cloning
    • Stem Cuttings
    • Vector Delivery
    • Examples of GMOs
    • cDNA and Microarrays
    • Gene Therapy
    • Gene Silencing

Topic 4: Ecology

  • 4.1 Species, communities and ecosystems
    • Species
    • Ecology Terms
    • Modes of Nutrition
    • Autotrophs
    • Heterotrophs
    • Nutrient Cycling
    • Mesocosms 
    • Chi Squared Test
    • Types of Metabolism
    • Species Interactions
    • Niches
    • Chi Squared Table
  • 4.2 Energy flow
    • Energy Source
    • Energy Flow
    • Energy Loss
    • Energy Efficiency
    • Pyramids of Energy
    • Ecological Productivity
    • Food Webs
    • Ecological Pyramids
    • Biomagnification
  • 4.3 Carbon cycling
    • Carbon Cycle
    • Carbon Compounds
    • Aquatic Conversions
    • Methane
    • Fossil Fuels
    • Combustion
    • Carbon Fluxes
    • Biogeochemical Cycles
    • Ocean Acidification
    • Biofuels
  • 4.4 Climate change
    • Greenhouse Gases
    • Greenhouse Effect
    • CO2 Concentrations
    • Climate Changes
    • Ocean Acidification
    • Greenhouse Debate
    • Water Cycle
    • Precautionary Principle
    • Carbon Footprint
    • Greenhouse Impacts

Topic 5: Evolution and biodiversity

  • 5.1 Evidence for evolution
    • Evolution
    • Fossil Record
    • Selective Breeding
    • Comparative Anatomy
    • Speciation
    • Evolution Example
    • Other Evidence
    • Fossilisation
    • Geological Time Scale
    • Radioactive Dating
  • 5.2 Natural selection
    • Natural Selection
    • Variation
    • Competition
    • Adaptations
    • Allele Frequency
    • Adaptive Radiation
    • Antibiotic Resistance
    • Theories of Evolution
    • Selection Pressures
    • Species Diversification
    • Artificial Gene Transfer
  • 5.3 Classification of biodiversity
    • Binomial System
    • Domains of Life
    • Hierarchy of Taxa
    • Classification
    • Plant Phyla
    • Animal Phyla
    • Vertebrate Classes
    • Dichotomous Keys
    • Past Nomenclatures
    • Archaea vs Eubacteria
    • Animal Complexity
    • Virus Classification
  • 5.4 Cladistics
    • Clades
    • Cladograms
    • Molecular Evidence
    • Structural Evidence
    • Clade Reclassification
    • In Situ Hybridisation
    • Mitochondrial DNA

Topic 6: Human physiology

  • 6.1 Digestion and absorption
    • Digestive System
    • Mechanical Digestion
    • Chemical Digestion
    • Small Intestine
    • Absorption
    • Starch Digestion
    • Modelling Digestion
    • Stages of Digestion
    • Lipid Digestion
    • Lipid Absorption
    • Sections of the Gut
  • 6.2 The blood system
    • Circulation
    • Arteries
    • Capillaries
    • Veins
    • Vessel Comparison
    • Heart Structure
    • Heart Beat
    • Heart Rate
    • Cardiac Cycle
    • Heart Disease
    • Blood Composition
    • Blood Pressure
    • Electrocardiography
  • 6.3 Defence against infectious disease
    • Surface Barriers
    • Clotting
    • Phagocytes
    • Lymphocytes
    • Antibiotics
    • Penicillin
    • HIV Infection
    • Pathogens
    • Lines of Defense
    • Inflammation
    • Types of Leukocytes
    • Haemophilia
    • Immunity Analogy
  • 6.4 Gas exchange
    • Ventilation
    • Lung Structure
    • Pneumocytes
    • Mechanism of Breathing
    • Respiratory Muscles
    • Lung Disorders
    • Spirometry
    • Lung Capacity
    • Effect of Exercise
    • More Lung Disorders
  • 6.5 Neurons and synapses
    • Neurons
    • Resting Potential
    • Action Potential
    • Nerve Impulses
    • Oscilloscope Traces
    • Myelination
    • Synaptic Transfer
    • Neurotransmitters
    • Graded Potentials
    • Nervous System
    • Stimulus-Response
    • Reflex Actions
    • Summation
    • Types of Neurotransmitters
  • 6.6 Hormones, homeostasis and reproduction
    • Insulin and Glucagon
    • Thyroxin
    • Leptin
    • Melatonin
    • Sexual Reproduction
    • Sex Development
    • Male Reproductive System
    • Female Reproductive System
    • Menstrual Cycle
    • In Vitro Fertilisation
    • Homeostasis
    • Feedback Loops
    • Endocrine System
    • Types of Hormones
    • Gender Issues
    • Menstrual Events

Additional Higher Level (AHL) Topics

Topic 7: Nucleic acids

  • 7.1 DNA structure and replication
    • Hershey and Chase
    • Structure of DNA
    • DNA Replication (HL)
    • Okazaki Fragments
    • DNA Sequencing
    • Non-coding DNA
    • Nucleosomes
    • DNA Experiments
    • Origins of Replication
    • Supercoiling
    • Genes versus Repetitive DNA
    • Telomerase
  • 7.2 Transcription and gene expression
    • Sections of a Gene
    • Transcription (HL)
    • Messenger RNA
    • Gene Expression
    • Epigenetics
    • Types of RNA
    • Operons
    • RNA Interference
    • Reverse Transcription
    • Microarrays
  • 7.3 Translation
    • Ribosomes and tRNA
    • tRNA Activation
    • Translation (HL)
    • Polysomes
    • Protein Destinations
    • Protein Structure
    • Protein Modification
    • Protein Expression
    • Amino Acid Polarity
    • Fibrous vs Globular Proteins
    • Visualising Proteins

Topic 8: Metabolism, cell respiration and photosynthesis

  • 8.1 Metabolism
    • Metabolic Pathways
    • Activation Energy
    • Enzyme Inhibition
    • Feedback Inhibition
    • Enzyme Kinetics
    • Rational Drug Design
    • Models of Action
    • Allosterism
    • Yeast-2-Hybrid System
  • 8.2 Cell respiration
    • Energy Conversions
    • Glycolysis
    • Link Reaction
    • Krebs Cycle
    • Electron Transport Chain
    • Aerobic Overview
    • Mitochondria
    • Uses of ATP
    • Energy Sources
    • Anaerobic versus Aerobic Respiration
    • Phosphagen System
  • 8.3 Photosynthesis
    • Photosynthesis
    • Light Dependent Reactions
    • Photophosphorylation
    • Light Independent Reactions
    • Calvin Cycle
    • Chloroplast
    • Photosynthesis vs Respiration
    • Accessory Pigments
    • C3, C4 and CAM Plants
    • Global Artificial Photosynthesis Project (GAP project) 

Topic 9: Plant biology

  • 9.1 Transport in the xylem of plants
    • Transpiration
    • Evaporation
    • Transpiration Stream
    • Root Uptake
    • Xylem Structure
    • Water Conservation
    • Plant Experiments
    • Leaf Tissue
    • Stem Tissue
    • Root Tissue
  • 9.2 Transport in the phloem of plants
    • Active Translocation
    • Phloem Structure
    • Phloem Loading
    • Mass Flow
    • Translocation Rate
    • Xylem versus Phloem
    • Storage Organs
    • Fungal Hyphae
  • 9.3 Growth in plants
    • Meristems
    • Apical Growth
    • Auxin
    • Tropisms
    • Micropropagation
    • Lateral Growth
    • Plant Hormones
  • 9.4 Reproduction in plants
    • Plant Reproduction
    • Flowering
    • Flower Structure
    • Photoperiodism
    • Seed Structure
    • Germination
    • Monocots versus Dicots
    • Germination Stages

Topic 10: Genetics and evolution

  • 10.1 Meiosis
    • Interphase
    • Stages of Meiosis
    • Random Assortment
    • Chiasmata
    • Crossing Over
    • Drawing Meiosis
    • Meiosis vs Mitosis
    • Stages of Prophase
    • Mendel and Meiosis
  • 10.2 Inheritance
    • Dihybrid Crosses
    • Linked Genes
    • Recombinants
    • Chi Squared Test
    • Chi Squared Table
    • Polygenic Traits
    • Test Cross
    • Centimorgan
  • 10.3 Gene pools and speciation
    • Evolution
    • Allele Distribution
    • Types of Selection
    • Isolation Barriers
    • Speciation
    • Pace of Speciation
    • Species Caveats
    • Allopolyploidy
    • Extinction
    • Polymorphisms
    • Hardy-Weinberg Principle

Topic 11: Animal physiology

  • 11.1 Antibody production and vaccination
    • Self versus Non-Self
    • Pathogenesis
    • Clonal Selection
    • Antibodies
    • Immunity
    • Allergens
    • Vaccination
    • Monoclonal Antibodies
    • Lymphatic System
    • Immune Pathways
    • Types of Immunity
    • Immune Disorders
  • 11.2 Movement
    • Skeletal Framework
    • Joints
    • Muscles
    • Muscle Fibres
    • Sarcomeres
    • Muscle Contraction
    • State of Contraction
    • Types of Levers
    • Types of Muscles
    • Slow vs Fast Twitch
  • 11.3 The kidney and osmoregulation
    • Excretory Systems
    • Malpighian Tubules
    • Kidneys
    • Nephrons
    • Ultrafiltration
    • Selective Reabsorption
    • Osmoregulation
    • Water Balance
    • Kidney Disease
    • Kidney Stones
    • Renin
  • 11.4 Sexual reproduction
    • Gametogenesis
    • Reproductive Tissue
    • Egg and Sperm
    • Animal Fertilization
    • Human Fertilization
    • Embryo Development
    • Human Chorionic Gonadotropin
    • Placenta
    • Birth Process
    • Gestation Periods
    • Semen Production
    • Amniotic Sac

Optional Topics

Option A: Neurobiology and behavior (Core topics)

  • A.1 Neural development
    • Neurulation
    • Spina Bifida
    • Neuron Development
    • Synaptic Formation
    • Neuroplasticity
    • Strokes
    • Gastrulation
    • Types of Neuroglia
  • A.2 The human brain
    • Brain Formation
    • Brain Sections
    • Brain Functions
    • Cerebral Cortex
    • Cerebral Hemispheres
    • Autonomic Control
    • Brain Damage
    • Encephalization
    • Brain Metabolism
    • Brain Matter
    • Sensorimotor Areas
    • Blood-Brain Barrier
  • A.3 Perception of stimuli
    • Sensory Perception
    • Sensory Structures
    • Photoreception
    • Visual Processing
    • Hearing
    • Vestibular System
    • Olfaction
    • Perception Issues
    • Types of Vision
    • Edge Enhancement
    • Gustation

Option A: Neurobiology and behaviour (Additional higher level topics)

  • A.4 Innate and learned behaviour
    • Innate Behaviour
    • Reflex Arcs
    • Learned Behaviour
    • Conditioning
    • Birdsong Development
    • Memory
    • Habituation
    • Insight Learning
  • A.5 Neuropharmacology
    • Synaptic Transmission
    • Neuromodulators
    • Psychoactive Drugs
    • Anesthetics
    • Endorphins
    • Addiction
    • Types of Neurotransmitters
    • Anti-Drug Vaccines
  • A.6 Ethology
    • Ethology
    • Migration
    • Altruism
    • Foraging
    • Breeding Behaviours
    • Innate versus Learned Behaviour
    • Social Hierarchies
    • Sexual Dimorphism

Option B: Biotechnology and bioinformatics (Core topics)

  • B.1 Microbiology: organisms in industry
    • Microorganisms
    • Gram Staining
    • Bactericides
    • Fermenters
    • Batch versus Continuous Culture
    • Pathway Engineering
    • Biogas Production
    • Archaea versus Eubacteria
    • Types of Eubacteria
    • Biofuels
  • B.2 Biotechnology in agriculture
    • Transgenics
    • Gene Identification
    • Gene Delivery Systems
    • Gene Expression
    • GM Crops
    • Environmental Impact
    • Other GM Examples
    • Edible Vaccines
  • B.3 Environmental protection
    • Bioremediation
    • Pollutant Metabolism
    • Biofilms
    • Use of Biofilms
    • Bacteriophages
    • Eutrophication
    • Plastic Pollution
    • Biomagnification

Option B: Biotechnology and bioinformatics (Additional higher level topics)

  • B.4 Medicine
    • Disease Markers
    • DNA Microarrays
    • PCR Analysis
    • enzyme-linked immunosorbent assay (ELISA)
    • Tracking Experiments
    • Biopharming
    • Gene Therapy
    • Pharmacogenomics
    • Gene Editing
    • Yeast-2-Hybrid System
  • B.5 Bioinformatics
    • Databases
    • Gene Discovery
    • Sequence Alignment
    • Phylogenetics
    • Gene Knockouts
    • RNA Interference
    • Allele Frequencies

Option C: Ecology and conservation (Core topics)

  • C.1 Species and communities
    • Survival Factors
    • Species Distribution
    • Ecological Niche
    • Species Interactions
    • Keystone Species
    • Plant Survival
    • Animal Survival
  • C.2 Communities and ecosystems
    • Trophic Levels
    • Energy Conversions
    • Feed Conversion Ratio
    • Types of Ecosystems
    • Ecosystem Analysis
    • Primary Succession
    • Ecological Disturbance
    • Types of Biomes
    • Ecological Pyramids
    • Sustainable Food Practices
  • C.3 Impacts of humans on ecosystems
    • Invasive Species
    • Biological Control
    • Biomagnification
    • Plastic Pollution
    • Chlorofluorocarbons
    • Earth Spheres
  • C.4 Conservation of biodiversity
    • Indicator Species
    • Biodiversity
    • Biogeographic Factors
    • Conservation
    • Endangered Species
    • Extinction

Option C: Ecology and conservation (Additional higher level topics)

  • C.5 Population ecology
    • Population Size
    • Population Sampling
    • Population Growth
    • Sigmoid Growth Curve
    • Population Factors
    • Sustainable Yields
    • r / K Strategies
    • Population Clocks
  • C.6 Nitrogen and phosphorus cycles
    • Nitrogen Cycle
    • Waterlogging
    • Phosphorus Cycle
    • Phosphate Availability
    • Eutrophication
    • Soil Content
    • Haber Process
    • Sulphur Cycle

Option D: Human physiology (Core topics)

  • D.1 Human nutrition
    • Essential Nutrients
    • Energy Sources
    • Amino Acids
    • Lipids
    • Vitamins
    • Minerals
    • Appetite and Diet
    • Dietary Intake
    • Food Pyramids
    • Dietary Supplements
  • D.2 Digestion
    • Exocrine Glands
    • Gastric Secretions
    • Stomach Acid
    • Intestinal Villi
    • Dietary Fibre
    • Digestive Infections
    • Digestive Juices
    • Gastric Pits
  • D.3 Functions of the liver
    • Liver Blood Flow
    • Liver Structure
    • Nutrient Supply
    • Detoxification
    • Plasma Proteins
    • Erythrocyte Recycling
    • Jaundice
    • Deamination
    • Liver and Alcohol
  • D.4 The heart
    • Cardiac Muscle
    • Cardiac Conduction
    • Heart Sounds
    • Electrocardiography
    • Cardiac Output
    • Heart Disorders
    • Heart Treatments
    • Circulation
    • Heart Measurements

Option D: Human physiology (Additional higher level topics)

  • D.5 Hormones and metabolism
    • Endocrine Glands
    • Types of Hormones
    • Pituitary Gland
    • Growth Hormone
    • Lactation
    • Types of Signalling
    • Hormone Comparison
    • Feedback Loops
    • Iodine Deficiency
  • D.6 Transport of respiratory gases
    • Lung Tissue
    • Oxygen Dissociation Curve
    • Carbon Dioxide Transport
    • Blood pH
    • Bohr Shift
    • Respiratory Control
    • High Altitude Training
    • Emphysema
    • Asthma
    • Lung Cancer

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