School / IB / BIOLOGY SL / Theme A: Unity and diversity Question practice
Theme A: Unity and diversity About this practice Cell theory and prokaryote/eukaryote diversity, water and biomolecule properties, species classification, and evolution and biodiversity.
Biology SL Theme A: Unity and diversity
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3 Distinguish between prokaryotic and eukaryotic cells in terms of their genetic material and membrane-bound organelles. Medium 4 marks No calculator + 4 Marking analysis: A learner attempts the following task: “Distinguish between prokaryotic and eukaryotic cells in terms of their genetic material and membrane-bound organelles.” Their response addresses only this point: “States that prokaryotic cells have a single circular DNA molecule that is not enclosed by a nuclear membrane, free in the cytoplasm.” Evaluate the response against the complete 4-mark task. Identify what earns credit and state every additional requirement needed for full marks. Marking analysis Medium 4 marks No calculator + 11 Explain the process of allopatric speciation. Medium 4 marks No calculator + 12 Marking analysis: A learner attempts the following task: “Explain the process of allopatric speciation.” Their response addresses only this point: “States that a population becomes geographically separated into two groups by a physical barrier (e.g. a mountain range, river or ocean), preventing gene flow between them.” Evaluate the response against the complete 4-mark task. Identify what earns credit and state every additional requirement needed for full marks. Marking analysis Medium 4 marks No calculator + 19 Outline two human activities that threaten biodiversity, and for each, state the primary mechanism of harm. Medium 4 marks No calculator + 20 Marking analysis: A learner attempts the following task: “Outline two human activities that threaten biodiversity, and for each, state the primary mechanism of harm.” Their response addresses only this point: “States habitat destruction (e.g. deforestation, land conversion for agriculture) as a first threat.” Evaluate the response against the complete 4-mark task. Identify what earns credit and state every additional requirement needed for full marks. Marking analysis Medium 4 marks No calculator + 29 Outline the process of natural selection, using antibiotic resistance in bacteria as an example. Medium 4 marks No calculator + 30 Marking analysis: A learner attempts the following task: “Outline the process of natural selection, using antibiotic resistance in bacteria as an example.” Their response addresses only this point: “States that genetic variation exists naturally within a population, e.g. some bacteria may already carry a mutation providing antibiotic resistance.” Evaluate the response against the complete 4-mark task. Identify what earns credit and state every additional requirement needed for full marks. Marking analysis Medium 4 marks No calculator + 31 In a population, 9% of individuals show a recessive phenotype (genotype aa). Assuming the population is in Hardy-Weinberg equilibrium, (a) calculate the frequency of the recessive allele (q), (b) calculate the frequency of the dominant allele (p), and (c) calculate the percentage of the population that are heterozygous carriers (Aa). Medium 5 marks Calculator + 32 Marking analysis: A learner attempts the following task: “In a population, 9% of individuals show a recessive phenotype (genotype aa). Assuming the population is in Hardy-Weinberg equilibrium, (a) calculate the frequency of the recessive allele (q), (b) calculate the frequency of the dominant allele (p), and (c) calculate the percentage of the population that are heterozygous carriers (Aa).” Their response addresses only this point: “States the Hardy-Weinberg equations: p + q = 1 and p² + 2pq + q² = 1.” Evaluate the response against the complete 5-mark task. Identify what earns credit and state every additional requirement needed for full marks. Marking analysis Medium 5 marks Calculator + Self-assessed Not marked yet
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