IB Biology HL study plan

Build a comparison table of the three domains of life and of the major eukaryotic kingdoms, listing cell type, cell wall composition, nutrition mode, and one distinguishing organelle for each group.

Construct a dichotomous key that separates at least eight named organisms using observable features only, then test the key on three unfamiliar organisms and revise any ambiguous couplet.

Explain how cladistics differs from Linnaean classification, using one example where a traditional grouping conflicts with a clade, and state which evidence (molecular or morphological) supports each.

Describe the evidence for the endosymbiotic theory of mitochondria and chloroplasts, naming at least four independent lines of evidence and one counter-argument with its rebuttal.

Sketch and label the structure of a bacterial cell, a plant cell, and an animal cell side by side, annotating three structures that are present in only one of the three.

Explain the mechanism of natural selection as a five-step chain (variation, heritability, differential survival, change in allele frequency, reproductive isolation) and apply it to one named example of directional selection.

Distinguish between analogous and homologous structures and use each concept to evaluate a claim about convergent evolution in two named species.

Describe the processes of speciation (allopatric and sympatric) and identify the specific barrier operating in two named case studies.

Outline the evidence for evolution from molecular data, including the use of cytochrome c or ribosomal RNA sequence comparisons, and explain why molecular clocks are only approximate.

Compare the rates and patterns of evolution proposed by gradualism and punctuated equilibrium, and state which fossil evidence supports each.

Draw and label the fluid mosaic model of the membrane, and explain the function of phospholipids, cholesterol, glycoproteins, and integral and peripheral proteins in transport and recognition.

Compare simple diffusion, facilitated diffusion, osmosis, and active transport in a table covering concentration gradient direction, energy requirement, membrane protein involvement, and one biological example of each.

Explain how surface area to volume ratio constrains cell size and shape, and calculate the ratio for three cells of different dimensions to show the trend.

Describe the structure and function of the villus, the alveolus, and the nephron, identifying the specific structural adaptation that maximises exchange in each.

Explain the role of the heart in double circulation, tracing the pathway of blood through the chambers, valves, and major vessels, and relating the thickness of each chamber wall to its function.

Interpret a set of transport data (for example, water potential measurements or rates of diffusion at different concentrations) by calculating means, identifying the trend, and stating one limitation of the method used.

Design a controlled experiment to investigate the effect of one named variable on osmosis in plant tissue, specifying the independent, dependent, and at least three controlled variables, plus how each is measured or monitored.

Explain how to reduce error and uncertainty in a practical, distinguishing between random and systematic error and between precision and accuracy, with one concrete example of each.

Describe how to construct and use a calibration curve, and state the assumptions required when interpolating a value from it.

Evaluate the strengths and weaknesses of a described experimental method and propose two specific improvements with justification.

Construct food chains and webs from a described community and identify producers, consumers, decomposers, and trophic levels, then calculate the energy transfer efficiency between two consecutive levels.

Explain why energy is lost at each trophic level and use this to justify the typical limit on the number of trophic levels in a food chain.

Describe the carbon cycle and the nitrogen cycle, naming the specific organisms and processes at each step, and explain how one human activity disrupts each cycle.

Explain the greenhouse effect, distinguishing natural from enhanced, and evaluate two named mitigation strategies by their mechanism and their limitation.

Describe the process of eutrophication and the mechanism by which it reduces dissolved oxygen, and propose two management interventions with justification.

Explain the principles of Hardy-Weinberg equilibrium, state its five conditions, and calculate allele and genotype frequencies from given data, including one case where the observed frequencies deviate and one reason why.

Describe the causes of variation (mutation, meiosis, random fertilisation, sexual reproduction) and explain how each contributes to genetic diversity in a population.

Explain the structure and behaviour of chromosomes in meiosis, including crossing over and independent assortment, and relate each to genetic variation.

Outline the inheritance of a named genetic disorder, using a pedigree or test-cross to predict the probability of an affected offspring.

Explain how antibiotic resistance in bacteria demonstrates natural selection in real time, and describe one mechanism of horizontal gene transfer that accelerates it.

Describe the structure of DNA and RNA and explain how the structure of DNA enables semi-conservative replication, naming the enzymes involved at each step.

Explain the processes of transcription and translation, and describe one named mutation and its effect on the polypeptide produced.

Describe the polymerase chain reaction and gel electrophoresis, and explain how each is used in a named application such as DNA profiling or gene testing.

Explain the principles of genetic modification and evaluate one named example (for example, Golden Rice or Bt maize) by benefit, risk, and ethical consideration.

Compare mitosis and meiosis in a table covering number of divisions, crossing over, chromosome number in daughter cells, and biological purpose.

Complete two full timed practice papers under exam conditions and self-mark against the mark scheme, recording every lost mark by domain.

Identify the three weakest sub-topics from the marked papers and write a one-page correction sheet for each, stating the misconception and the correct statement.

Rehearse data-analysis and extended-response technique: practise interpreting a graph with error bars and structuring a six-mark evaluation answer with a clear judgement.

Recite from memory the core definitions and units for the five domains, checking each against the syllabus glossary and correcting any drift.

Review the internal-assessment criteria and annotate your week-4 report to show where each criterion is evidenced, then revise one section to strengthen the weakest criterion.