Biology · QCAA

Full Biology syllabus

Drill from units to topics, subtopics and individual learning objectives. Every LO is wired up to AI-marked practice questions.

124 LOs

▶1 — Cells and multicellular organisms34 LOs

▶Cells as the basis of life13 LOs

●Compare active and passive transport.●Compare organelle composition of different cell types using electron micrographs.●Compare prokaryotic and eukaryotic cells.●Describe how stem cells originate through the process of mitosis and differentiate into specialised cells to form tissues.●Describe how the hierarchical organisation of cells, tissues, organs and systems allow multicellular organisms to - obtain nutrients, e.g. digestive and circulatory systems - exchange gases, e.g. respiratory and circulatory systems - remove wastes, e.g. respiratory, circulatory and excretory systems.●Describe the structure and function of the cell membrane based on the fluid mosaic model, including the role of protein channels, phospholipids, cholesterol and glycoproteins.●Distinguish between unipotent, multipotent, pluripotent and totipotent stem cel ls.●Explain how the cell membrane regulates movement of substances into and out of the cell via - osmosis - simple diffusion - facilitated diffusion - protein-mediated active transport - endocytosis and exocytosis.●Explain how the size of a cell is limited by surface area-to-volume ratio and rate of diffusion.●Explain that each body system contains specialised cells and tissues that are structurally suited to function, including - size and shape (SA:V ratio) - organelle composition.●Identify key organelles and their functions, including the nucleus, mitochondria, rough ER, ribosomes, smooth ER, Golgi apparatus, lysosomes, vacuoles and chloroplasts.●Interpret data from an experiment investigating the effect of surface area-to-volume ratio on the rate of diffusion. Biology 2025 v1.3 ●Use a light microscope or photographs to - view tissues from the respiratory, circulatory, excretory, digestive and/or plant systems - compare epithelial, connective, muscle and nervous tissues - calculate total magnification and field of view.

▶Exchange of nutrients and wastes11 LOs

●Compare the induced-fit and lock-and-key models of enzyme function.●Describe how closed circulatory systems facilitate the efficient transport of materials to and from all cells in the body.●Describe the roles of amylase, protease and lipase in chemical digestion.●Describe the structure and function of carbohydrates, proteins and lipids.●Describe the structure and function of enzymes, including the role of the active site.●Explain how enzyme activity is affected by factors such as temperature, pH, presence of inhibitors and substrate concentration.●Explain how glomerular filtration, selective reabsorption and secretion across nephron membranes contribute to the removal of waste.●Explain how metabolic processes, such as digestion, are controlled and regulated by enzymes.●Explain how structural features of exchange surfaces in the digestive and circulatory systems of mammals (e.g. villi and capillaries) allow for efficient nutrient exchange.●Identify the parts of a nephron and their functions in the production of urine, i.e. glomerulus, Bowman’s capsule, proximal tubule, Loop of Henle, distal tubule and collecting duct.●Interpret data from an experiment investigating factors affecting enzyme activity.

▶Cellular energy, gas exchange and plant physiology10 LOs

●Analyse data to predict the direction that materials will be exchanged between - alveoli and capillaries - capillaries and muscle tissue.●Compare aerobic and anaerobic respiration.●Compare the structure and function of xylem and phloem tissues.●Describe the process of aerobic respiration, identifying the location in the cell and net inputs and outputs of - glycolysis - Krebs cycle and electron transport chain - the overall reaction (C6H12O6 + 6O2 → 6CO2 + 6H2O + 36–38 ATP).●Describe the process of photosynthesis, identifying the location in the cell and net inputs and outputs of - light-dependent reactions - light-independent reactions - the overall reaction (6CO2 + 6H2O + light energy → C6H12O6 + 6O2).●Distinguish between catabolism and anabolism.●Explain how ATP allows energy from catabolic reactions to be used in anabolic reactions.●Explain how stomata and guard cells facilitate gas exchange in plants.●Explain how structural features of exchange surfaces in the respiratory and circulatory systems of mammals (alveoli and capillaries) allow for efficient gas exchange.●Interpret data from an experiment investigating the effect of light intensity, temperature, wind or humidity on the rate of transpiration.

▶2 — Maintaining the internal environment29 LOs

▶Homeostasis14 LOs

●Analyse feedback-control diagrams to identify the stimulus, receptor/s, control centre, effector/s and communication pathway/s in different scenarios.●Compare the number and distribution of stomata in plants adapted to different environments.●Describe how hormones relay messages to cells displaying specific receptors via the circulatory or lymphatic system.●Describe the structure and function of nerve cells, including dendrites, soma, body, axon, myelin sheath, nodes of Ranvier, axon terminal and synapse.●Distinguish between sensory neurons, interneurons and motor neurons.●Explain how receptor binding alters cellular activity, recognising that a cell’s sensitivity to a specific hormone is directly related to the number of receptors it displays for that hormone.●Explain how structural and homeostatic mechanisms maintain water balance in plants, including the roles of stomata, vacuoles, cuticle and abscisic acid.●Explain how the nervous and endocrine systems use negative feedback to coordinate responses to internal/external stimuli and maintain homeostasis (stimulus-response model).●Explain osmoregulation in humans, including the role antidiuretic hormone (ADH) and the kidney using feedback control diagrams.●Explain the passage of a nerve impulse in terms of transmission of an action potential and synaptic transmission, referring to neurotransmitters, receptors, synaptic cleft, vesicles, postsynaptic and presynaptic neurons and signal transduction.●Explain thermoregulation in humans, including the role of sweating, shivering, vasodilation and vasoconstriction using feedback control diagrams.●Explain thermoregulatory mechanisms of endotherms, including - structural features: brown adipose tissue, insulation - behavioural responses: kleptothermy, hibernation, aestivation and topor - physiological mechanisms: evaporative heat loss, thermogenesis and vasomotor control.●Identify the different types of sensory receptors and their stimuli, including chemoreceptors, thermoreceptors, mechanoreceptors, photoreceptors and nociceptors.●Interpret data from an experiment comparing the number and distribution of stomata in plants adapted to different environments.

▶Infectious disease and epidemiology15 LOs

●Analyse data to - predict outbreaks - determine the source of an outbreak - infer the mode of disease transmission - determine the effectiveness of different strategies in controlling the spread of disease.●Compare active and passive immunity, both naturally acquired and artificially acquired.●Describe modes of disease transmission, including direct contact, contact with body fluids, contaminated food, contaminated water and disease-specific vectors. Biology 2025 v1.3 ●Describe the inflammatory response, including the roles of - prostaglandins and vasodilation - neutrophils and macrophages - natural killer cells.●Describe the innate immune responses in plants, including - physical defence strategies: barriers and leaf structures - chemical defence strategies: plant defensins and production of toxins.●Distinguish between infectious and non-infectious disease.●Explain how adherence factors, invasion factors, capsules and toxins affect pathogenesis.●Explain how host cells recognise self from non-self.●Explain how personal hygiene measures, contact tracing and quarantine are used to control the spread of disease.●Explain how the following factors affect the spread of disease - persistence of pathogens within host - transmission mechanism - proportion of the population that are immune or have been immunised - mobility of individuals in the affected population.●Explain the adaptive immune response, including the - humoral response (B lymphocytes, antibodies) - cell-mediated response (T lymphocytes) - role of memory cells.●Identify key features of prions, viruses, bacteria, fungi, protists and parasites.●Identify the three lines of defence in vertebrates - the innate immune response: skin and mucous membranes (non-specific) - inflammatory response and complement system (non-specific) - adaptive immune response (specific).●Interpret data from an experiment investigating the effect of an ant imicrobial agent on the growth of a microorganism.●Interpret long-term immune response data.

▶3 — Biodiversity and the interconnectedness of life31 LOs

▶Biodiversity and populations16 LOs

●Calculate population growth rate and change using birth, death, immigration and emigration data. Biology 2025 v1.3 The following subject matter may be assessed in the internal assessments.●Compare species diversity in two spatially variant ecosystems of the same classification. Biology 2025 v1.3 ●Compare the reproductive strategies and growth curves of K- and r- strategists.●Describe genetic, species and ecosystem diversity.●Describe how sampling can be used to investigate the species diversity of a given area, considering the most appropriate  sampling method: random, systematic, stratified  sampling technique: quadrats, line transect, belt-transect, capture-recapture  strategies to minimise bias: size and number of samples, random-number generators, counting criteria, calibrating equipment and noting associated precision  measure/s of diversity.●Describe how the distribution and abundance of species in an ecosystem are influenced by - biotic factors — food availability, competition for resources, predation, disease - abiotic factors — space, shelter, availability of water, nutrients, environmental conditions.●Describe the biological species concept and identify its limitations.●Determine the diversity of species using measures such as species richness, evenness (relative species abundance), percentage cover, percentage frequency and Simpson’s diversity index, 𝑆𝐷𝐼 = 1 − (∑ 𝑛(𝑛−1) 𝑁(𝑁−1)).●Explain that ecosystems are composed of varied habitats, including microhabitats, which may impact the distribution of species (e.g. uniform, random or clumped), and therefore the validity and reliability of different sampling methods/techniques.●Identify and explain different modes of population growth, including - exponential growth (J-curve) - logistic growth (S-curve).●Identify the major taxa in the Linnaean system of biological classification and explain how it is used to classify and name species.●Interpret data from an experiment investigating how abiotic factors affect the distribution, abundance and/or biodiversity of species in an ecosystem.●Interpret data to classify and name ecosystems using Specht’s classification system and the Holdridge life zone classification scheme.●Use dichotomous keys to identify and classify organisms.●Use the Lincoln index (𝑁 = 𝑀×𝑛 𝑚) to estimate the size of a population.●Use the process of stratified sampling to - identify different habitats within an ecosystem - investigate changes to abiotic factors in different strata - investigate changes to community composition in different strata, e.g. layers of a forest - infer species interactions within and between strata - classify an ecosystem.

▶Functioning ecosystems and succession15 LOs

●Analyse ecological data (e.g. food webs, population data) to - identify keystone species - infer species interactions - predict the outcomes of removing species from an ecosystem.●Analyse food chains, energy flow diagrams and ecological pyramids to determine - efficiencies of energy and biomass transfer - gross and net productivity - loss of energy through radiation, reflection and absorption.●Describe the concept of an ecological niche.●Describe the process of ecological succession.●Describe the transfer and transformation of matter (water, carbon, nitrogen) as it cycles through ecosystems.●Distinguish between primary and secondary succession.●Explain how overexploitation, habitat destruction, monocultures and pollution affect community structure and ecosystem functioning.●Explain how the carrying capacity of an ecosystem can be impacted by changes to biotic and abiotic factors, including climatic events.●Explain successional changes, with reference to species interactions, abiotic factors, K- and r-selected species, biodiversity and biomass.●Explain the competitive exclusion principle.●Explain the critical role that keystone species play in maintaining the structur e of a community.●Explain the following species interactions: predation, competition, mutualism, commensalism and parasitism.●Explain the transfer and transformation of energy as it flows through the biotic components of an ecosystem, including the - conversion of light into chemical energy - production of biomass and its interactions with components of the carbon cycle - loss of energy as heat.●Identify the features of pioneer species that make them effective colonisers.●Interpret ecological data to compare ecosystems across spatial and temporal scales. Biology 2025 v1.3 The following subject matter may be assessed in the internal assessments.

▶4 — Heredity and continuity of life30 LOs

▶Genetics and heredity18 LOs

●Compare spermatogenesis and oogenesis.●Describe dominant, recessive, autosomal, sex-linked, polygenic and multiple-allele inheritance. Biology 2025 v1.3 ●Describe how PCR and gel electrophoresis are used in DNA profiling and explain how differences in DNA allow for characteristic banding patterns.●Describe the process of DNA replication with reference to helicase, DNA polymerase and the joining of Okazaki fragments.●Describe the process of making recombinant DNA, including the role of restriction enzymes, plasmids and DNA ligase.●Describe the process of meiosis and explain how crossing over, independent assortment and random fertilisation produce variation in the genotypes of offspring.●Describe the structure and function of DNA, genes and chromosomes in prokaryotes and eukaryotes, including - helical structure, nucleotide composition (nitrogenous base + sugar + phosphate), complementary base pairing, hydrogen bonds - introns and exons, promoter region - homologous chromosomes (i.e. sister chromatids, centromeres, telomeres, gene loci, alleles), role of histones - circular chromosomes (i.e. prokaryotes, mitochondria, chloroplasts) and plasmids.●Determine the effect of point and frameshift mutations on polypeptides using the genetic code.●Explain how errors in DNA replication and damage by physical/chemical factors in the environment can lead to point and frameshift mutations.●Explain how errors in meiosis can lead to chromosomal abnormalities such as insertions, deletions, duplications, inversions, translocations and aneuploidy.●Explain how gene expression is regulated in response to environmental signals and to allow for cell differentiation, including - chemical tags that affect chromatin structure (heterochromatin vs. euchromatin) - proteins that bind to the promoter region of a gene (transcription factors).●Explain how genes from the HOX transcription factor family regulate morphology.●Explain the process of protein synthesis in terms of - transcription of a gene into messenger RNA in the nucleus - RNA processing (5’ cap, RNA splicing, poly-A tail) - translation of mRNA into an amino acid sequence at the ribosome, referring to transfer RNA, codons and anticodons.●Extract DNA from strawberries, kiwifruit or wheat germ.●Identify ploidy changes within a human karyotype to predict a genetic disorder.●Infer patterns of inheritance and predict frequencies of genotypes and phenotypes from genetic data, including - histograms (polygenic inheritance) - pedigrees (dominant/recessive, autosomal/sex-linked) - Punnett squares (dominant/recessive, autosomal/sex-linked and multiple-allele inheritance).●Interpret DNA profiles from gel electrophoresis (laboratory work or computer simulation).●Interpret DNA profiles from gel electrophoresis. The following subject matter may be assessed in the internal assessments.

▶Continuity of life on Earth12 LOs

●Analyse data to determine the effect of a selection pressure on a population, recognising that selection for an allele can be positive or negative.●Analyse genotypic changes for a selective pressure in a gene pool (laboratory work or computer simulation).●Calculate allele frequencies from genotype data.●Describe how macroevolutionary changes result from the accumulation of microevolutionary changes using examples of divergent, convergent, parallel and coevolution.●Determine episodes of evolutionary radiation and mass extinctions from an evolutionary timescale of life on Earth (approximately 3.5 billion years). Biology 2025 v1.3 The following subject matter may be assessed in the internal assessments.●Distinguish between microevolution and macroevolution.●Explain how comparative genomics provides evidence for the theory of evolution and how conserved sequences can be used to date divergence.●Explain how geographic, temporal and spatial isolation influence gene flow and may lead to allopatric, sympatric and parapatric speciation.●Explain microevolutionary change through the main processes of mutation, gene flow and genetic drift.●Explain natural selection and identify the three main types of phenotypic selection: stabili sing, directional and disruptive.●Explain why populations with reduced genetic diversity face increased risk of extinction.●Infer species relatedness from cladograms, phylograms and molecular sequence data.

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