IB DP Biology 2025 Syllabus
The new DP Biology course was launched in February 2023 for first teaching in August 2023. First assessment will take place in May 2025. IBDP Biology courses are here as per new syllabus and guidelines provided by the board. Details of changes in pattern and syllabus are also mentioned on this page.
1. Molecules & Metabolism
1.1: Water
- Life Origin: Life originated in water, and most processes occur in it.
- Polarity and Bonding: Water molecules form hydrogen bonds due to polarity.
- Diagram: Show water molecules and hydrogen bonds.
- Cohesion: Water molecules stick together, benefiting organisms.
- Adhesion: Water sticks to polar/charged surfaces, impacting life.
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- Significance and Hypotheses: Water’s role in evolution and possible origins include asteroids, gravity, and temperature changes.
- Extraterrestrial Life: Water’s link to the search for extraterrestrial life involves the “Goldilocks zone,” where conditions are just right for liquid water.
1.2: Nucleic Acid
- DNA/RNA: DNA is genetic material; some viruses use RNA.
- Nucleotide Structure: Draw nucleotides with circles (phosphate), pentagons (sugar), rectangles (base).
- Backbone: Understand sugar-phosphate bonding.
- Nitrogenous Bases: Know base types and functions.
- RNA Structure: Draw RNA as a polymer of nucleotide monomers.
- DNA Structure: Draw DNA’s antiparallel double helix.
- DNA vs. RNA: Visualize differences.
- Base Pairing: Enables replication and expression.
- Diversity: DNA’s sequences allow immense information storage.
- Conservation: The genetic code shows universal ancestry.
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- Directionality: Recall 5′ to 3′ directionality in RNA and DNA.
- Purine-Pyrimidine Bonding: Stabilizes DNA helix through hydrogen bonding.
- Nucleosome Structure: Histones wrapped by DNA to form nucleosomes.
- Hershey-Chase Experiment: Demonstrated DNA as genetic material.
- Chargaff’s Data: Supported DNA structure with base-pairing rules.
1.3: Carbohydrates and Lipids
- Covalent Bonds & Carbon: Carbon forms diverse molecules.
- Condensation Reactions: Create macromolecules like polysaccharides.
- Hydrolysis: Breaks polymers into monomers.
- Monosaccharides: Learn glucose, pentoses, hexoses.
- Polysaccharides: Starch and glycogen store energy.
- Cellulose: Structural role in plants.
- Glycoproteins: Role in cell recognition (ABO antigens).
- Lipids: Hydrophobic nature.
- Triglycerides & Phospholipids: Form via condensation reactions.
- Fatty Acids: Differentiate saturated, monounsaturated, and polyunsaturated.
- Triglyceride Function: Energy storage and insulation.
- Phospholipid Bilayers: Form due to amphipathic nature.
- Steroid Passage: Non-polar steroids like testosterone pass membranes.
1.4: Proteins
- Amino Acid Structure: Draw generalized amino acids.
- Condensation Reactions: Form dipeptides and polypeptides.
- Amino Acid Requirements: Know dietary essentials.
- Peptide Diversity: Infinite variety in polypeptides.
- Denaturation: Effects of pH and temperature on proteins.
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- Amino Acids: Chemical diversity of R-groups explains protein diversity.
- Primary Structure: Linear sequence determines protein folding.
- Secondary Structure: Alpha helices and beta pleated sheets.
- Tertiary Structure: Dependent on various bonds and interactions.
- Quaternary Structure: Interaction of multiple polypeptides (e.g., haemoglobin).
- Protein Form and Function: Compare globular (insulin) and fibrous (collagen) proteins.
1.5: Enzymes & Metabolism
- Enzyme Role: Catalysts in metabolism.
- Anabolic/Catabolic Reactions: Synthesize and break down molecules.
- Active Sites: Structure and function.
- Induced-Fit Binding: Interaction between substrate and active site.
- Enzyme-Substrate Specificity: Structure influences specificity and denaturation.
- Rate Influences: Temperature, pH, and substrate concentration.
- Activation Energy: Enzymes lower activation energy.
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- Enzymatic Reactions: Include glycolysis, Krebs cycle, and digestion.
- Heat Energy: Metabolic reactions release heat.
- Pathways: Glycolysis (linear), Krebs cycle (cyclical).
- Inhibition: Competitive vs. non-competitive (e.g., statins, penicillin).
- Feedback Inhibition: Isoleucine as an end-product inhibitor.
1.6: Respiration
- ATP: Distributes energy within cells.
- Energy Usage: Active transport, anabolism, and movement.
- ATP-ADP Interconversion: Understand energy transfer.
- Cell Respiration: Produces ATP from carbon compounds.
- Aerobic vs. Anaerobic: Compare substrates, oxygen, ATP yield, and waste products. Write equations.
- Respiration Variables: Factors affecting the respiration rate
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- NAD in Respiration: NAD transports hydrogen during respiration.
- Glycolysis: Glucose to pyruvate, ATP production, and NAD reduction.
- Anaerobic Respiration: Regeneration of NAD, lactate formation.
- Link Reaction: Pyruvate to acetyl-CoA, producing NADH and CO₂.
- Krebs Cycle: Decarboxylation and oxidation yield ATP and NADH.
- ETC: NADH transfers energy to the electron transport chain.
- Chemiosmosis: Proton gradient generates ATP in mitochondria.
1.7: Photosynthesis
- Energy Transformation: Light converts to chemical energy during photosynthesis.
- Photosynthesis Equation: Write word and symbol equation.
- Oxygen Production: Byproduct from water splitting.
- Chromatography: Separating pigments.
- Light Absorption: Wavelength-specific absorption by pigments.
- Absorption vs. Action Spectra: Compare spectra.
- Limiting Factors: Investigate CO₂, light intensity, temperature effects.
- CO₂ Enrichment: Predict future growth rates.
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- Photosystems: Capture light energy, excite electrons.
- Pigment Arrays: Increase efficiency of light absorption.
- Photolysis of Water: Generates oxygen in Photosystem II.
- Calvin Cycle: Carbon fixation by Rubisco forms 3-phosphoglycerate.
- Chemiosmosis in Thylakoids: Proton gradient and ATP production.
1.8: DNA Replication
- DNA Replication: Produces exact copies with identical base sequences.
- Semi-Conservative Replication: Role of complementary base pairing.
- Enzymes: Helicase unwinds DNA, DNA polymerase synthesizes new strands.
- PCR & Gel Electrophoresis: Amplify and separate DNA.
- Applications: DNA profiling for forensics, paternity tests.
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- Directionality: DNA polymerases synthesize in the 5′ to 3′ direction.
- Leading vs. Lagging Strand: Continuous vs. discontinuous replication.
- Enzymes in Replication: Roles of DNA primase, polymerase, ligase.
- Proofreading: DNA polymerases check for errors during replication.
1.9: Protein Synthesis
- Transcription: RNA synthesis using DNA template.
- Hydrogen Bonding: Complementary base pairing in transcription.
- Gene Expression: Transcription enables it.
- Translation: Synthesize polypeptides from mRNA.
- Ribosomes & tRNA: Key roles in translation.
- Codons and Anticodons: Complementary pairing between tRNA and mRNA.
- Genetic Code: Degeneracy and universality.
- mRNA Reading: Deduce amino acid sequence.
- Translation Process: Ribosome movement and peptide bonding.
- Point Mutations: Impact on protein structure.
- Translation Initiation: Explain initiation process with subunit and tRNA binding.
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- Transcription and Translation: Both processes occur in a 5′ to 3′ direction.
- Transcription Initiation: Occurs at the promoter region of DNA.
- Non-coding Sequences: Regulate gene expression (e.g., introns, telomeres).
- Post-transcriptional Modification: Removal of introns, addition of caps and tails.
- Alternative Splicing: Creates different proteins from the same gene.
1.10: Mutations
- Gene Mutations: Define and distinguish types (substitution, insertion, deletion).
- SNPs: Explain base substitution effects.
- Insertion & Deletion: Consequences for genetic information.
- Causes: Explain mutation causes.
- Randomness: Mutations occur unpredictably.
- Impact on Germ vs. Somatic Cells: Understand inheritance and cancer risk.
- Genetic Variation: Mutation as a source of variation.
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- Gene Knockout: Used to study gene function by disabling it.
- CRISPR-Cas9: Used for precise gene editing, including real-world applications.
- Conserved Sequences: Highly conserved sequences suggest essential functions across species.
2. Cells & Signalling
2.1: Cell Structure
- Basic Unit: Cells form the foundation of all living organisms.
- Microscopy Skills: Includes mounts, staining, magnification, and image analysis.
- Microscopy Developments: Advancements like electron and cryogenic microscopy.
- Common Structures: Plasma membrane, cytoplasm, and ribosomes across all cells.
- Prokaryote Structure: Cell wall, plasma membrane, cytoplasm, DNA loop, and 70S ribosomes.
- Eukaryote Structure: Plasma membrane, 80S ribosomes, organelles like nucleus, mitochondria, etc.
- Unicellular Organisms: Processes like homeostasis, nutrition, movement, reproduction.
- Eukaryotic Differences: Between animals, fungi, and plants.
- Atypical Cells: Examples of unusual eukaryotic structures.
- Cell Identification: Identify types through light and electron microscopy.
- Draw & Annotate: Structures from electron micrographs, such as mitochondria and Golgi apparatus.
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- Early Earth Conditions: Focuses on the formation of carbon compounds in the pre-biotic world.
- Living vs. Non-living: Cells are the smallest units of life, distinguishing life forms from non-living matter.
- Cell Origin: Explains spontaneous origin via catalysis, self-replication, and compartmentalization.
- Miller-Urey Experiment: Provides evidence for the origin of organic compounds.
- Vesicle Formation: Discusses coalescence of fatty acids into bilayers.
- RNA as First Genetic Material: Explores RNA’s role before DNA.
- LUCA Evidence: Shared genes and universal genetic code.
- Dating the First Cells: Methods used to estimate origins.
- Hydrothermal Vent Origins: Evidence supporting life’s origins near hydrothermal vents.
- Endosymbiosis: Explains the origin of eukaryotic cells through symbiotic relationships, with mitochondria and chloroplasts as examples.
- Cell Differentiation: Discusses specialization for tissue development in multicellular organisms.
- Multicellularity: Evolutionary benefits include specialized functions and larger organism size.
2.2: Membranes and Transport
- Lipid Bilayers: Basis of cell membranes.
- Hydrophobic Barrier: Prevents large molecules and hydrophilic particles from crossing.
- Diffusion: Movement of gases like oxygen and carbon dioxide.
- Membrane Proteins: Integral and peripheral roles in structure and function.
- Osmosis: Water movement through membranes and aquaporins.
- Facilitated Diffusion: Structure and role of channel proteins.
- Active Transport: Role of pump proteins.
- Selective Permeability: Membrane selectivity and its factors.
- Glycoproteins/Glycolipids: Structure and function in cell recognition.
- Fluid Mosaic Model: Describes membrane structure, including phospholipids and cholesterol.
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- Lipid Bilayers & Fluidity: How fatty acid composition affects membrane fluidity.
- Cholesterol Role: In membrane fluidity in animal cells.
- Membrane Dynamics: Endocytosis and exocytosis processes.
- Ion Channels: Gated ion channels in neurons, like nicotinic acetylcholine receptors.
- Sodium-Potassium Pump: Its role in generating membrane potentials.
- Glucose Cotransporters: Involved in indirect active transport.
- Cell Adhesion: Role of cell-adhesion molecules in forming tissues.
2.3: Organelles & Compartmentalization
- Organelles: Subunits for specialized cellular functions.
- Nucleus-Cytoplasm Separation: Advantage of compartmentalization.
- Compartmentalization: Benefits for cellular efficiency and organization.
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- Virus Structure: Comprises size, nucleic acid, capsid, and lack of cytoplasm.
- Virus Diversity: Variations in structural design among viruses.
- Lytic Cycle: Overview of bacteriophage lambda’s replication process.
- Lysogenic Cycle: Integration of viral DNA in host genome.
- Viral Origins: Evidence of multiple evolutionary paths.
- Viral Evolution: Examples include influenza and HIV, showing rapid adaptability.
- Mitochondria Adaptations: For efficient ATP production.
- Chloroplast Adaptations: Maximized for photosynthesis.
- Nuclear Membrane: Functional benefits of a double membrane.
- Ribosomes & Rough ER: Roles in protein synthesis.
- Golgi Apparatus: Involved in protein modification and sorting.
- Vesicles: Transport roles, including clathrin-coated vesicles
2.4: Cell Specialization
- Differentiation: Development from unspecialized to specialized cells.
- Stem Cells: Properties and uses in development.
- Stem Cell Niches: Locations in adult humans and their functions.
- Stem Cell Types: Differences between totipotent, pluripotent, and multipotent cells.
- Cell Size Specialization: Variations in gametes, blood cells, and neurons.
- SA Ratios: Limits on cell size due to surface area constraints.
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- Surface Area Adaptations: Flattening, microvilli, invagination for greater efficiency.
- Pneumocytes: Type I and II cells’ role in alveoli.
- Cardiac Muscle: Adaptations for continuous function.
- Gametes: Adaptations of sperm and egg cells.
2.5: Neural Signalling
- Neurons: Cells carrying electrical impulses.
- Resting Potential: Maintenance of sodium-potassium gradients.
- Action Potentials: Propagation along nerve fibers.
- Nerve Impulse Speed: Comparison of squid giant axons and smaller fibers.
- Synapses: Junctions between neurons and effector cells.
- Neurotransmitters: Release from presynaptic membranes.
- Excitatory Postsynaptic Potentials: Example of acetylcholine.
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- Receptors & Ligands: Binding for cell signaling.
- Quorum Sensing: Example of bacterial signaling.
- Signaling Molecules: Hormones, neurotransmitters, etc.
- Hormonal Diversity: Chemical classes, including amines and steroids.
- Localized vs. Distant Signaling: Different effects based on signal type.
- Transmembrane Receptors: Differences between types, like G-protein linked and ion channels.
- Signal Transduction: Pathway initiation via receptors.
- Membrane Potential Changes: Involvement of neurotransmitter receptors.
- G-protein Activation: Through receptor signaling.
- Epinephrine Receptor: G-protein and cAMP pathway example.
- Insulin Signaling: Example of tyrosine kinase receptor pathways.
- Intracellular Receptors: Regulation of gene expression by steroid hormones.
- Oestradiol & Progesterone: Hormonal effects on target cells.
- Feedback Regulation: Positive and negative feedback in signaling.
- Depolarization/Repolarization: During action potentials.
- Action Potential Propagation: Via local currents along axons.
- Oscilloscope Traces: Visualizing action potentials.
- Saltatory Conduction: Faster signal transmission in myelinated axons.
- Synaptic Transmission: Effects of external chemicals like neonicotinoids.
- Inhibitory Neurotransmitters: Generating inhibitory postsynaptic potentials.
- Summation: Effects of excitatory and inhibitory inputs.
- Pain Perception: Neurons and free nerve endings.
- Consciousness: Emergent property from neuronal interactions.
2.6: Cell Division
- Cell Division: Generation of new cells through mitosis and meiosis.
- Cytokinesis: Splitting of cytoplasm between daughter cells.
- Unequal Cytokinesis: Examples like oogenesis and yeast budding.
- Roles of Mitosis/Meiosis: Role in growth, repair, and reproduction.
- DNA Replication: Prerequisite for both types of cell division.
- Chromosome Movement: Shared features in mitosis and meiosis.
- Phases of Mitosis: Identifiable stages.
- Meiosis: Diploid to haploid reduction division.
- Non-disjunction: Example of errors in meiosis (e.g., Down syndrome).
- Variation: Genetic diversity through meiosis.
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- Cell Proliferation: Growth, repair, and replacement via cell division.
- Cell Cycle Phases: G1, S, G2, mitosis, cytokinesis.
- Interphase Growth: Cellular activity during this phase.
- Cyclins: Proteins controlling the cell cycle.
- Cancer Genes: Mutations in proto-oncogenes and tumor suppressor genes.
- Tumour Types: Differences between benign, malignant, primary, and secondary tumours.
- Gene Expression: Mechanism affecting phenotypes.
- Transcription Regulation: Role of DNA-binding proteins.
- mRNA Degradation: Regulation of translation.
- Epigenesis: Cellular differentiation in multicellular organisms.
- Gene, Transcriptome, Proteome: Differences at molecular levels.
- Epigenetic Tags: Methylation of promoters and histones.
- Epigenetic Inheritance: Gene expression through heritable changes.
- Environmental Impact: Effects on gene expression, e.g., pollution.
- Tag Removal: In gametes, with examples like tigons and ligers.
- Monozygotic Twins: Gene expression affected by the environment.
- External Factors: Hormonal and biochemical impacts on gene expression.
2.7: Water Potential
- Solvation: Water acts as a solvent due to hydrogen bonding and attraction to ions.
- Osmosis: Water movement from lower to higher solute concentrations.
- Water in Cells: Movement based on hypotonic, hypertonic, or isotonic solutions.
- Plant Cells: Effects of water movement in hypotonic/hypertonic solutions.
- Animal Cells: Effects of water movement on cells lacking walls.
- Cell Walls: Turgor and plasmolysis in plant cells.
- Medical Applications: Isotonic solutions in IV fluids and organ transplants.
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- Water Potential: Defined as potential energy per unit volume.
- Water Movement: From higher to lower water potential.
- Water Potential Equation: ψw = ψs + ψp (solute + pressure potential).
- Water in Plant Cells: Movements in hypotonic/hypertonic solutions.