IB Biology Syllabus Checklist

Recall the conditions on early Earth and the pre-biotic formation of carbon compounds.

Recall that cells as the smallest units of self-sustaining life, and discuss the differences between something that is living and something that is non-living.

Explaining the spontaneous origin of cells, including: catalysis, self-replication of molecules, self-assembly and the emergence of compartmentalization as necessary requirements.

Evidence for the origin of carbon compounds and  the Miller–Urey experiment.

Understand the spontaneous formation of vesicles by coalescence of fatty acids into spherical bilayers.

Explain why RNA is a presumed first genetic material.

Recall the evidence for a last universal common ancestor (LUCA), including: the universal genetic code and shared genes across all organisms.

The approaches used to estimate dates of the first living cells and the last universal common ancestor.

Recall the evidence for the evolution of the last universal common ancestor in the vicinity of hydrothermal vents.

Explain the origin of eukaryotic cells by endosymbiosis, including the relevant evidence.

Recall cell differentiation as the process for developing specialized tissues in multicellular organisms.

Recall the evolution of multicellularity and its advantages.

Recall lipid bilayers as the basis of cell membranes.

Understand lipid bilayers as barriers since hydrophobic hydrocarbon chains that form the core of a membrane have low permeability to large molecules and hydrophilic particles.

Recall simple diffusion across membranes using the movement of oxygen and carbon dioxide as examples.

Recall the structures, locations and functions of integral and peripheral proteins in membranes.

Describe the movement of water molecules across membranes by osmosis, and the role of aquaporins.

Understand the structure and function of channel proteins for facilitated diffusion.

Understand the functioning of pump proteins for active transport.

Explain selectivity in membrane permeability.

Describe the structure and function of glycoproteins and glycolipids.

Draw and describe th fluid mosaic model of membrane structure, including: peripheral and integral proteins, glycoproteins, phospholipids and cholesterol.

Understand organelles as discrete subunits of cells that are adapted to perform specific functions.

State the advantage of the separation of the nucleus and cytoplasm into separate compartments.

Recall the advantages of compartmentalization in the cytoplasm of cells.

Describe the production of unspecialized cells following fertilization and their development into specialized cells by differentiation.

Recall the properties of stem cells.

State the location and function of stem cell niches in adult humans, using two examples.

Describe the differences between totipotent, pluripotent and multipotent stem cells.

Expplain cell size as an aspect of specialization, including: male and female gametes, red and white blood cells, neurons and striated muscle fibres.

Understand surface area-to-volume ratios and their constraints on cell size.

Recall receptors as proteins with binding sites for specific signalling chemicals, including use of the term “ligand” for the signalling chemical.

Recall cell signalling by bacteria in quorum sensing using the example of bioluminescence in the marine bacterium Vibrio fischeri.

Distinguish hormones, neurotransmitters, cytokines and calcium ions as examples of functional categories of signalling chemicals in animals.

Describe the chemical diversity of hormones and neurotransmitters, including: amines, proteins, steroids, amino acids, and nitrous oxide.

Contrast localized and distant effects of signalling molecules.

Outline the differences between transmembrane receptors in a plasma membrane and intracellular receptors in the cytoplasm or nucleus.

Understand the tnitiation of signal transduction pathways by receptors.

Recall transmembrane receptors and their association to neurotransmitters and changes to membrane potential.

Recall transmembrane receptors that activate G proteins.

Explain the mechanism of action of epinephrine (adrenaline) receptors, including G protein and cyclic AMP (cAMP).

Recall insulin as an example of a pathway involving transmembrane receptors with tyrosine kinase activity.

Recall intracellular receptors that affect gene expression, including: oestradiol, progesterone, and testosterone as examples.

Explain the effects of the hormones oestradiol and progesterone on target cells.

Describe the regulation of cell signalling pathways by positive and negative feedback, including examples for each.

Explain depolarization and repolarization during action potentials.

Understand the propagation of an action potential along a nerve fibre/axon as a result of local currents.

Interpret oscilloscope traces showing resting potentials and action potentials.

Understand saltatory conduction in myelinated fibres to achieve faster impulses.

Describe the rffects of exogenous chemicals on synaptic transmission using neonicotinoids as an example.

Describe inhibitory neurotransmitters and their generation of inhibitory postsynaptic potentials.

Understand the summation of the effects of excitatory and inhibitory neurotransmitters in a postsynaptic neuron.

Explain the perception of pain by neurons with free nerve endings in the skin.

Understand consciousness as a property that emerges from the interaction of individual neurons in the brain.

Understand the process of cell proliferation for growth, cell replacement and tissue repair, including skin, plant meristems and early-stage animal embryos as examples.

Describe the phases of the cell cycle, including: G1, S and G2 as the stages of interphase, followed by mitosis and then cytokinesis.

Understand cell growth during interphase.

Describe the control of the cell cycle using cyclins. Specific examples are not required.

Describe the consequences of mutations in genes that control the cell cycle, including use of the terms: "proto-oncogenes", "oncogenes", and "tumour suppressor genes".

Outline the differences between tumours in rates of cell division and growth and in the capacity for metastasis and invasion of neighbouring tissue. Use the terms: “benign”, “malignant”, “primary tumour” and “secondary tumour”, and distinguish between tumours that do and do not cause cancer.

Understand solvation with water as the solvent, including: hydrogen bond formation, and attractions between ions and polar water molecules.

Explain water movement from less concentrated to more concentrated solutions, including use of the terms “hypertonic”, “hypotonic” and “isotonic”.

Describe water movement by osmosis into or out of cells, including use of the terms: hypotonic, hypertonic, and isotonic.

Predict changes due to water movement in plant tissue bathed in hypotonic and those bathed in hypertonic solutions.

Describe the effects of water movement on cells that lack a cell wall, including swelling and bursting in a hypotonic medium, and shrinkage and crenation in a hypertonic medium.

Describe the effects of water movement on cells with a cell wall, including use of the terms "turgor" and "plasmolysis".

Recall the medical applications of isotonic solutions, including intravenous fluids and bathing of organs for transplantation.

Understand the variation between organisms as a defining feature of life.

Recall that species are groups of organisms with shared traits according to Linnaeus.

Use the Binomial system for naming organisms.

Understand the biological species concept: a group of organisms that can breed and produce fertile offspring. Recall challenges associated with this definition.

State the difficulties distinguishing between populations and species due to divergence of non- interbreeding populations during speciation.

Appreciate diversity in chromosome numbers of plant and animal species, specifically in humans and chimpanzees.

Classify chromosomes invovled in Karyotyping and karyograms and analyse the evidence for the hypothesis that chromosome 2 in humans arose from the fusion of chromosomes 12 and 13 with a shared primate ancestor.

Understand that the genome is all the genetic information of an organism, and variations give diversity within species.

Recall the diversity of eukaryote genomes and that variation between species is much larger than variation within a species.

Be able to compare genome sizes from a database.

State current and potential future uses of whole genome sequencing.

Understand the need for classification of organisms.

Recall the difficulties of classifying organisms into the traditional hierarchy of taxa.

State the advantages of classification corresponding to evolutionary relationships, including predictions within clades.

Recall clades as groups of organisms with common ancestry and shared characteristics.

Understand the use of the gradual accumulation of sequence differences as the basis for estimates of when clades diverged from a common ancestor (molecular clock).

Use example base sequences of genes or amino acid sequences of proteins to construct cladograms.

Analyse cladograms to deduce evolutionary relationships, common ancestors and clades. Understand the terms “root”, “node” and “terminal branch”.

Use cladistics to investigate whether the classification of groups corresponds to evolutionary relationships.

Understand the classification of all organisms into three domains using evidence from rRNA base sequences.

Recall the adaptations of foetal and adult haemoglobin for the transport of oxygen.

Understand the Bohr shift.

Explain the shape of oxygen dissociation curves as a means of representing the affinity of haemoglobin for oxygen.

Explain the release and reuptake of tissue fluid in capillaries due to pressure differences.

Outline the composition of, and exchange of substances between. tissue fluid and cells.

Understand the drainage of excess tissue fluid into lymph ducts.

Describe the differences between the single circulation of bony fish and the double circulation of mammals.

Recall the adaptations of the mammalian heart for delivering pressurized blood to the arteries, including the: cardiac muscle, pacemaker, atria, ventricles, valves, septum and coronary vessels. Identify these structures on visual diagrams.

Recall the stages in the cardiac cycle and interpret systolic and diastolic blood pressure measurements from data and graphs.

Explain the generation of root pressure in xylem vessels by active transport of mineral ions.

Describe the adaptations of phloem sieve tubes and companion cells for translocation of sap, including: sieve plates, reduced cytoplasm and organelles, no nucleus for sieve tube elements and presence of many mitochondria.

Understand system integration as a necessary process in living systems.

Appreciate cells, tissues, organs and body systems as a hierarchy of subsystems that are integrated in a multicellular living organism.

Distinguish between the roles of the nervous system and endocrine system in sending messages.

Understand the brain as a central information integration organ.

Describe the spinal cord as an integrating centre for unconscious processes and distinguish between conscious and unconscious processes.

Understand the input to the spinal cord and cerebral hemispheres through sensory neurons.

Understand the output from the cerebral hemispheres to muscles through motor neurons.

Recall nerves as bundles of nerve fibres of both sensory and motor neurons, including their structure.

Understand pain reflex arcs as an example of involuntary responses with skeletal muscle as the effector.

Recall the role of the cerebellum in coordinating skeletal muscle contraction and balance.

Understand the modulation of sleep patterns by melatonin secretion as a part of circadian rhythms.

Describe epinephrine (adrenaline) secretion by the adrenal glands to prepare the body for vigorous activity.

Describe the control of the endocrine system by the hypothalamus and pituitary gland.

Recall feedback control of heart rate following sensory input from baroreceptors and chemoreceptors. Understand the role of the medulla in coordinating responses and sending nerve impulses to the heart to change the heart’s stroke volume and heart rate.

Understand feedback control of ventilation rate following sensory input from chemoreceptors.

Explain the control of peristalsis in the digestive system by the central nervous system and enteric nervous system (ENS).

Recall pathogens as the cause of infectious diseases.

Describe skin and mucous membranes as a primary defence.

Explain the sealing of cuts in skin by blood clotting, including the release of clotting factors, the cascade pathway, and trapping of erythrocytes to form a clot.

Explain the differences between the innate immune system and the adaptive immune system.

Describe infection control by phagocytes, including amoeboid movement from blood to sites of infection.

Understand lymphocytes as cells in the adaptive immune system that cooperate to produce antibodies.

Define antigens as recognition molecules that trigger antibody production.

Explain the activation of B-lymphocytes by helper T-lymphocytes.

Explain the multiplication of activated B-lymphocytes to form clones of antibody-secreting plasma cells.

Undesrtand immunity as a consequence of retaining memory cells.

Describe transmission of HIV in body fluids, including examples.

Understand the infection of lymphocytes by HIV with AIDS as a consequence.

Define antibiotics as chemicals that block processes occurring in bacteria but not in eukaryotic cells.

Describe the evolution of resistance to several antibiotics in strains of pathogenic bacteria.

Define zoonoses as infectious diseases that can transfer from other species to humans, including the examples of tuberculosis, rabies and Japanese encephalitis, and COVID-19.

Explain vaccines and the process of immunization.

Describe herd immunity and the prevention of epidemics.

Evaluate data related to the COVID-19 pandemic

Explain the control of the developmental changes of puberty by gonadotropin-releasing hormone and steroid sex hormones.

Explain spermatogenesis and oogenesis in humans, including: mitosis, cell growth, two divisions of meiosis and differentiation.

Explain the mechanisms to prevent polyspermy.

Describe the development of a blastocyst and subsequent implantation into the endometrium.

Describe pregnancy testing by detection of human chorionic gonadotropin secretion.

Understand the role of the placenta in foetal development inside the uterus, including the exchange processes that occur.

Recall the hormonal control of pregnancy and childbirth.

Outline hormone replacement therapy and the risk of coronary heart disease.

Understand segregation and independent assortment of unlinked genes in meiosis.

Utilise punnett grids for predicting genotypic and phenotypic ratios in dihybrid crosses involving pairs of unlinked autosomal genes, and understand how the 9:3:3:1 and 1:1:1:1 ratios are derived.

Appreciate Loci of human genes and their polypeptide products.

Explain autosomal gene linkage and use appropriate symbols to denote them.

Understand recombinants in crosses involving two linked or unlinked genes.

Use the chi-squared test on data from dihybrid crosses and understand statistical significance, null/alternative hypothesis, and the idea of observed versus expected results.

Understand the role of the kidney in osmoregulation and excretion.

Describe the role of the glomerulus, Bowman’s capsule and proximal convoluted tubule in excretion.

Describe the role of the loop of Henle.

Explain osmoregulation by water reabsorption in the collecting ducts, including: osmoreceptors, antidiuretic hormone (ADH) secretion, and aquaporins.

Describe the changes in blood supply to organs in response to changes in activity using the examples of skeletal muscles, gut, brain and kidneys during sleep, vigorous physical activity and wakeful rest.

Define evolution as the change in the heritable characteristics of a population.

State the evidence for evolution from base sequences in DNA or RNA and amino acid sequences in proteins.

Recall the evidence for evolution from selective breeding of domesticated animals and crop plants.

Recall the evidence for evolution from homologous structures, including the example of pentadactyl limbs.

Recall convergent evolution as the origin of analogous structures, including one example.

Understand speciation,  the splitting of pre-existing species, as the only way in which new species have appeared.

Explaine the roles of reproductive isolation and differential selection in speciation, using the separation of bonobos and common chimpanzees by the Congo River as a specific example.

Defined biodiversity as the variety of life in all its forms, levels and combinations. Define ecosystem diversity, species diversity and genetic diversity.

Make comparisons between the current number of species on Earth and past levels of biodiversity.

Recall the causes of anthropogenic species extinction.

Recall two case studies of the causes of ecosystem loss,including the loss of mixed dipterocarp forest in Southeast Asia.

Recall evidence for a biodiversity crisis through examples.

Recall human population growth as a major cause of the current biodiversity crisis, as well as: hunting, urbanization, deforestation, pollution, diseases and invasive alien species.

Appreciate the need for several approaches to the conservation of biodiversity.

Appreciate the selection of evolutionarily distinct and globally endangered species for conservation prioritization in the EDGE of Existence programme.

Understand the ecological niche as the role of a species in an ecosystem, and the interactions that influence growth, survival and reproduction.

State differences between organisms that are obligate anaerobes, facultative anaerobes and obligate aerobes.

Recall photosynthesis as the mode of nutrition in plants, algae and several groups of photosynthetic prokaryotes.

Understand holozoic nutrition in animals.

Explain mixotrophic nutrition in some protists, includng Euglena as a well-known freshwater example.

State that saprotrophic nutrition occurs in some fungi and bacteria (decomposers).

Understand the diversity of nutrition in archae.

Explain the relationship between dentition and the diet of omnivorous and herbivorous representative members of the family Hominidae.

Recall the adaptations of herbivores for feeding on plants and of plants for resisting herbivory.

State the adaptations of predators for finding, catching and killing prey and of prey animals for resisting predation.

Explain the adaptations of plants for harvesting light, including examples from forest ecosystems.

Appreciation fundamental niches as the potential of a species based on adaptations and tolerance limits, and realized niches as the actual extent of a species niche when in competition with other species.

Explain competitive exclusion and the uniqueness of ecological niches using an example.

Define ecosystems as open systems in which both energy and matter can enter and exit.

Describe sunlight as the principal source of energy that sustains most ecosystems. Include exceptions such as ecosystems in caves.

Describe the flow of chemical energy through food chains.

Construct food chains and food webs to represent feeding relationships in a community.

Describe the supply of energy to decomposers as carbon compounds in organic matter coming from dead organisms.

Define autotrophs as organisms that use external energy sources to synthesize carbon compounds from simple inorganic substances.

Understand the use of light as the external energy source in photoautotrophs and oxidation reactions as the energy source in chemoautotrophs, using iron-oxidizing bacteria as an example of a chemoautotroph.

Define heterotrophs as organisms that use carbon compounds obtained from other organisms to synthesize the carbon compounds that they require.

Describe the release of energy in both autotrophs and heterotrophs by oxidation of carbon compounds in cell respiration.

Classify organisms into trophic levels, including use of the terms: “producer”, “primary consumer”, “secondary consumer” and “tertiary consumer”.

Construct energy pyramids.

Explain the reductions in energy availability at each successive stage in food chains due to large energy losses between trophic levels.

Understand heat loss to the environment in both autotrophs and heterotrophs due to conversion of chemical energy to heat in cell respiration.

Explain restrictions on the number of trophic levels in ecosystems due to energy losses.

Explain primary production as the accumulation of carbon compounds in biomass by autotrophs.

Define secondary production as the accumulation of carbon compounds in biomass by heterotrophs.

Construct carbon cycle diagrams.

Outline ecosystems as carbon sinks and carbon sources.

Explain the release of carbon dioxide into the atmosphere during combustion of biomass, peat, coal, oil and natural gas.

Analyse the Keeling Curve in terms of photosynthesis, respiration and combustion.

Explain the dependence of aerobic respiration on atmospheric oxygen produced by photosynthesis, and of photosynthesis on atmospheric carbon dioxide produced by respiration.

Understand the recycling of all chemical elements required by living organisms in ecosystems.

Understand the concept of the gene pool.

Appreciate allele frequencies of geographically isolated populations, including one example in humans.

Recall changes in allele frequency in the gene pool as a consequence of natural selection between individuals according to differences in their heritable traits.

Explain differences between directional, disruptive and stabilizing selection.

Recall the Hardy–Weinberg equation in calculations of allele or genotype frequencies: p² + 2pq + q² = 1.

Understand the Hardy–Weinberg conditions that must be maintained for a population to be in genetic equilibrium.

Understand artificial selection by the deliberate choice of traits.

Describe ecological succession and its causes.

Describe the changes occurring during primary succession using any suitable terrestrial example to illustrate: increases in size of plants, amount of primary production, species diversity, complexity of food webs and amount of nutrient cycling.

Understand cyclical succession in ecosystems through an example.

Understand climax communities and arrested succession through use of the examples of grazing by farm livestock and drainage of wetlands.

Define phenology as research into the timing of biological events.

Understand disruption to the synchrony of phenological events by climate change, including spring growth of the Arctic mouse-ear chickweed and arrival of migrating reindeer as an example. Recall a further local example, or use the breeding of the great tit and peak biomass of caterpillars in north European forests in its place.

Outine the increases to the number of insect life cycles within a year due to climate change through use of the spruce bark beetle as an example.

Recall evolution as a consequence of climate change, including changes in the fitness of colour variants of the tawny owl (Strix aluco) as an example.