Investigation inventory — 30 teachable paper/data alternatives
Each design supplies prerequisites, a question, real given inputs, variables, controls/sampling, analysis, checked practice and transfer in an existing unit. Synthetic data are invented for learning, not fabricated field observations. “Approved-type alternative” does not mean a human has already approved this class or learner; the review step below is required.
These are public, nonsecure paper/data practice activities, not performed laboratory work. No culture of unknown microbes, human biological samples, medical or genetic personal disclosures, unsafe chemicals, or DNA manipulation instructions are authorized. Use supplied data, approved reference images, or a preapproved non-destructive observation. An instructor must review safety, accessibility and the exact practical contract before any physical activity; a worksheet does not certify hands-on technique. A worksheet must not certify hands-on technique. No human biological samples or personal medical/genetic disclosures are required.
Proposed pacing, not performed-lab evidence: Allow roughly 15–25 minutes for source/model discussion, 20–35 for first-attempt analysis and 10–15 for transfer/defense per selected activity. Split molecular or statistical work across meetings by readiness. These are planning estimates, not time logs, pilot results or evidence of the AP laboratory requirement.
Assessment boundary: Keep public answers as nonsecure practice. The instructor supplies fresh variants and/or observes the approved technique separately, with criteria, permitted references and accessibility agreed before assessment. Each student has three tokens per term; each token retries one rubric criterion. Approved accommodations, equipment failures, and approved absences are handled separately and do not consume these tokens. Integration is reported separately and cannot lower the science grade or block a science demonstration pass. Science and practical criteria determine that pass.
U1 · Water, molecular building blocks and indicator controls [water-molecules]
Question: Which chemical claims can these model structures and controlled recorded colors actually support?
Prerequisites: Recognize atoms, polar bonds, subunits and a negative versus a positive control.
Inputs and calibration: Supplied dataset, level tasks, checked answers and transfer in the existing unit. molecule-links; indicator-records.
Specific reading: OpenStax Biology 2e (2018), 2.2 Water — Read Water’s Polarity, Water’s High Heat Capacity and Water as a Solvent. Explain a property with intermolecular hydrogen bonds rather than just naming the property. OpenStax Biology 2e (2018), 2.1 Atoms, Isotopes, Ions, and Molecules — Read chemical bonding and carbon-containing molecules. Track C, H, O, N, P and S as matter acquired from the environment, not created by cells. OpenStax Biology 2e (2018), 3.1 Synthesis of Biological Macromolecules — Compare dehydration synthesis with hydrolysis; count links in a linear chain. OpenStax Biology 2e (2018), 3.2 Carbohydrates — Compare the glucose linkages in starch and cellulose; connect linkage geometry with storage or structural function. OpenStax Biology 2e (2018), 3.3 Lipids — Compare fats, phospholipids and steroids. Explain why lipids are not one family of repeating-monomer polymers. OpenStax Biology 2e (2018), 3.4 Proteins — Read the four levels of protein structure and denaturation. Connect amino-acid side chains and folding to function. OpenStax Biology 2e (2018), 3.5 Nucleic Acids — Compare nucleotides, sugar-phosphate backbones and base pairing in DNA and RNA. NobelPrize.org: The Nobel Prize in Chemistry 1972 — Read the 1972 prize citations for Anfinsen, Moore and Stein. Connect the stated sequence/conformation and structure/catalysis questions to this unit; a prize summary is not a complete experimental record or a list of every contributor.
Materials
- Printed molecule-links and indicator-records tables; colored pencils or accessible text cards.
- The assigned water and macromolecule reference figures; no chemicals or food handling.
Variables: Compare molecule identity and recorded indicator response; keep the model’s volume, time and viewing conditions fixed.
Control/comparison: Water is the negative control; known starch and protein are separate positive controls with defined responses.
Sampling: These four records are demonstration cases, not independent estimates of food composition or assay reliability.
Procedure and analysis
- Label covalent links within molecules and hydrogen bonds between water molecules.
- Draw each chain; predict hydrolysis counts before consulting the worked answer.
- Check controls, classify X only within the supplied response rule, then diagnose the failed-control transfer case.
Retain molecular diagrams, link counts and a control-by-control interpretation; distinguish presence screening from concentration measurement.
Uncertainty: Color recognition, cross-reactivity and detection limits would need real calibration; none is estimated by this four-row illustration.
Evidence to science criteria: Science criteria 1 and 4: structure-to-function diagrams; criterion 3: hydrogen-bond mechanism; criterion 5: controlled interpretation plus separately observed approved technique, not a worksheet-only practical pass.
Human practical/safety review: Before use, the instructor must check the source, arithmetic, accessible format and approved assessment alternative; record the practical/safety review and any observation still required. This paper interpretation does not replace observed food-test handling if that technique remains in the agreed criterion.
U1 · Enzyme response, pH and independent replicates [enzyme-replicates]
Question: How does the modeled enzyme rate differ across pH treatments, and what does the observed variation mean?
Prerequisites: Read a rate axis, calculate a mean and distinguish vessels from repeated readings of one vessel.
Inputs and calibration: Supplied dataset, level tasks, checked answers and transfer in the existing unit. enzyme-ph; enzyme-substrate.
Specific reading: OpenStax Biology 2e (2018), 6.5 Enzymes — Read activation energy, active sites, induced fit, environmental effects and inhibitors. Distinguish rate from equilibrium and reversible inhibition from loss of folded structure.
Materials
- Supplied enzyme-ph and enzyme-substrate tables; graph paper or a spreadsheet.
- Calculator with square root; the displayed formulas and enzyme reading.
Variables: pH is the first explanatory variable and product rate the response; the second series changes substrate at fixed pH.
Control/comparison: Treat pH 7 as the reference condition, not an enzyme-free blank. A real experiment would also need an enzyme-free background control.
Sampling: Three independent vessel preparations per pH are biological/experimental replicates in this model; repeated readings of a vessel are not extra replicates.
Procedure and analysis
- Record the synthetic label, units and controlled conditions.
- Compute group means, ranges and selected-level SD/SE; show the individual points.
- Compare the substrate trend; propose one additional control and solve the new-rate transfer without copying a verdict.
Explain the trend through active-site chemistry and limiting substrate/enzyme; report the difference and uncertainty without an unearned significance claim.
Uncertainty: Only three independent replicates and three pH levels are supplied. No uncertainty is available for the substrate means or for an exact optimum.
Evidence to science criteria: Science criterion 2: enzyme mechanism and predictions; criterion 3: pH reasoning; criterion 4: rate graph with independent replicates; criterion 5: design/control defense, with actual handling still separately assessed.
Human practical/safety review: Before use, the instructor must check the source, arithmetic, accessible format and approved assessment alternative; record the practical/safety review and any observation still required. Use paper data only; this design authorizes no heating, peroxide use or chemical preparation.
U2 · Cell scale, organelles and compartment evidence [cell-geometry]
Question: What size and structural claims are justified by a scale bar and the supplied compartment evidence?
Prerequisites: Convert millimetres to micrometres, use ratios and distinguish image features from model labels.
Inputs and calibration: Supplied dataset, level tasks, checked answers and transfer in the existing unit. cell-cubes; image-scale; organelle-evidence.
Specific reading: OpenStax Biology 2e (2018), 4.1 Studying Cells — Compare microscopy magnification and resolution. Use a published scale bar rather than estimating a specimen size from screen size. OpenStax Biology 2e (2018), 4.2 Prokaryotic Cells — Compare the cell envelope, nucleoid and ribosomes with the eukaryotic cell drawing; prokaryotes are not less-evolved versions of modern eukaryotes. OpenStax Biology 2e (2018), 4.3 Eukaryotic Cells — Study nucleus, mitochondria and chloroplasts. Compare internal membranes and the endosymbiosis evidence. OpenStax Biology 2e (2018), 4.4 The Endomembrane System and Proteins — Trace a secreted protein from ribosome and rough ER through Golgi and vesicle; distinguish a model from an observed organelle. NobelPrize.org: The Nobel Prize in Chemistry 2014 — Read the 2014 recognition of Betzig, Hell and Moerner for super-resolved fluorescence microscopy. Explain why improved resolution differs from enlarging a print; do not claim our supplied scale record uses that method.
Materials
- Printed scale record, cell-cubes and organelle-evidence; ruler or equivalent accessible measurements.
- Assigned reference drawings/micrographs with their source captions; no specimen collection.
Variables: Compare model side length with area/volume; measure the object and scale at the same enlargement.
Control/comparison: Use the same source image and bar calibration; resizing one without the other invalidates the size calculation.
Sampling: One model image is not a biological sample distribution. Re-measuring the same image checks reading consistency, not biological replication.
Procedure and analysis
- Predict the size trend before calculating area/volume.
- Record the reference and scale; calculate the object width and separate visible from inferred structures.
- Trace the secretion pathway, compare ancestry evidence, and solve the changed-scale transfer.
Retain ratios with dimensions, source-annotated structure labels and a two-line evidence/limitation argument for compartment origins.
Uncertainty: Bar thickness, rounding, section plane and resolution limit size and identification; a textbook diagram is not an experimental image.
Evidence to science criteria: Science criteria 1, 3 and 5: organelle function and compartment/ancestry reasoning; criterion 4: calibrated image interpretation, with focusing/handling evidence retained separately.
Human practical/safety review: Before use, the instructor must check the source, arithmetic, accessible format and approved assessment alternative; record the practical/safety review and any observation still required. Any microscope focusing must be observed separately with a known prepared nonhuman slide or an agreed accessible practical alternative.
U2 · Transport, osmosis and pressure-aware water potential [membrane-model]
Question: Where does this modeled mass-change trend cross zero, and when does pressure reverse a concentration-only prediction?
Prerequisites: Percent change, concentration, membrane permeability; honors additionally uses Kelvin, signs and pressure units.
Inputs and calibration: Supplied dataset, level tasks, checked answers and transfer in the existing unit. osmosis-records; transport-models.
Specific reading: OpenStax Biology 2e (2018), 5.1 Components and Structure — Study the fluid-mosaic model, phospholipid orientation and membrane-protein roles. OpenStax Biology 2e (2018), 5.2 Passive Transport — Read diffusion, facilitated diffusion and tonicity. Separate solute permeability from water movement. OpenStax Biology 2e (2018), 5.3 Active Transport — Read primary and secondary active transport; identify the original energy source in a coupled gradient. OpenStax Biology 2e (2018), 5.4 Bulk Transport — Compare endocytosis and exocytosis with transport through channels; cargo is moved in vesicles, not through a pore.
Materials
- Supplied mass and transport records; graph paper or spreadsheet.
- Calculator and the supplied water-potential constants; no solutions or plant cutting.
Variables: Bath concentration is varied; percent mass change is the response. Initial mass, geometry, duration, temperature and blotting are modeled controls.
Control/comparison: Include the zero-solute comparison and identical processing; a real procedure also needs a balance check and a predefined handling method.
Sampling: Three distinct plants per treatment are independent units in the fictional design; repeated weighings or strips from one plant are subsamples.
Procedure and analysis
- Calculate individual and mean percent changes without deleting inconvenient values.
- Graph the supplied treatments and interpolate only the interval spanning zero.
- Defend membrane mechanisms; at honors level calculate total potentials and audit the replication alternative.
Retain original values, percent denominators, axes, interpolation and water-potential assumptions; state the observed/model distinction.
Uncertainty: Limited concentration spacing and variation in mass, blotting and plant origin limit the zero estimate; it is not a precise cellular solute assay.
Evidence to science criteria: Science criterion 2: transport and pressure-aware predictions; criterion 5: membrane structure/function. Retain careful data recording and stated model limits; this paper transport task does not assess microscopy.
Human practical/safety review: Before use, the instructor must check the source, arithmetic, accessible format and approved assessment alternative; record the practical/safety review and any observation still required. Do not infer any authorized chemical preparation or tissue-handling procedure from the paper design.
U3 · ATP coupling, carbon tracing and respiratory pathways [energy-coupling]
Question: Can a model conserve carbon while using free-energy coupling to support ATP-dependent cellular work?
Prerequisites: Follow atom counts, positive/negative energy changes and the difference between cytosol and mitochondrial membranes.
Inputs and calibration: Supplied dataset, level tasks, checked answers and transfer in the existing unit. coupled-reactions; respiration-carbon.
Specific reading: OpenStax Biology 2e (2018), 6.2 Potential, Kinetic, Free, and Activation Energy — Distinguish reaction free-energy change from activation energy and rate. OpenStax Biology 2e (2018), 6.4 ATP: Adenosine Triphosphate — Read energy coupling, including phosphate transfer to an intermediate. OpenStax Biology 2e (2018), 7.2 Glycolysis — Track one glucose into two three-carbon pyruvates and locate glycolysis in the cytosol. OpenStax Biology 2e (2018), 7.3 Oxidation of Pyruvate and the Citric Acid Cycle — Track carbon release during pyruvate oxidation and two turns of the cycle. OpenStax Biology 2e (2018), 7.4 Oxidative Phosphorylation — Identify the inner mitochondrial membrane, proton gradient, ATP synthase and oxygen’s role as terminal electron acceptor. OpenStax Biology 2e (2018), 7.5 Metabolism without Oxygen — Explain how fermentation regenerates NAD+ so glycolysis can continue; it is not an oxygen-producing pathway.
Materials
- Printed carbon ledger, coupled energy values and colored atom/electron tokens.
- Assigned pathway figures, calculator and an annotated cell outline.
Variables: Change the coupling partner or membrane-gradient condition while keeping the carbon starting inventory explicit.
Control/comparison: Use the intact-gradient and uncoupled-reaction models as comparisons; do not silently change the initial glucose count.
Sampling: These are stoichiometric models, not replicated respiration measurements; tokens represent atoms, not live cells.
Procedure and analysis
- Label compartments and separate atom, electron and energy arrows.
- Reconcile every input carbon with an intermediate or output; add coupled ΔG values.
- Predict the broken-gradient case and solve the altered-energy transfer with a stated rate limitation.
Keep a carbon ledger and mechanism explaining where coupling occurs, rather than a memorized fixed ATP total.
Uncertainty: The model omits alternative carbon fates, changing cellular concentrations, shuttle costs and proton leaks.
Evidence to science criteria: Science criteria 2–4: location, carbon balance and ATP coupling; criterion 5: testable perturbation design and limitations, with observed laboratory technique separate.
Human practical/safety review: Before use, the instructor must check the source, arithmetic, accessible format and approved assessment alternative; record the practical/safety review and any observation still required. No combustion, oxygen manipulation or live respirometer setup is authorized by this model.
U3 · Light reactions, carbon fixation and replicated oxygen budgets [photosynthesis-budget]
Question: What can replicated light/dark oxygen changes reveal about production under explicitly stated conditions?
Prerequisites: Calculate signed slopes, distinguish net from gross and recognize photosynthesis/respiration compartments.
Inputs and calibration: Supplied dataset, level tasks, checked answers and transfer in the existing unit. chamber-oxygen.
Specific reading: OpenStax Biology 2e (2018), 8.2 The Light-Dependent Reactions of Photosynthesis — Trace water splitting, electron transfer, the thylakoid proton gradient, ATP and NADPH; identify the source of released O₂. OpenStax Biology 2e (2018), 8.3 Using Light Energy to Make Organic Molecules — Trace CO₂ fixation in the stroma and distinguish carbon fixation from the light reactions. NobelPrize.org: The Nobel Prize in Chemistry 1961 — Read the 1961 citation for Melvin Calvin’s carbon-dioxide assimilation research. Connect that historical question to the carbon-fixation model; the oxygen table below is not Calvin’s dataset.
Materials
- Supplied chamber-oxygen records and a chloroplast diagram.
- Graph paper/spreadsheet, calculator and the assigned source sections.
Variables: Light condition is the explanatory variable; oxygen change per volume per minute is the response at matched biomass and temperature.
Control/comparison: The dark group estimates respiratory use; a proposed no-producer blank tests sensor drift or non-producer oxygen change.
Sampling: Three independent model chambers per condition, not six readings of one chamber; within-chamber time points are paired.
Procedure and analysis
- Retain starting values and compute a signed rate for every chamber.
- Plot individual rates and means; label any sample SD bars.
- Calculate conditional gross production, identify violated assumptions and defend the fresh oxygen case.
Retain chamber-level arithmetic, axes, light/dark comparisons and an explanation linking light reactions to carbon fixation.
Uncertainty: Equal respiration, no leakage and equal biomass are model assumptions; limited replicates do not prove the mechanism.
Evidence to science criteria: Science criteria 1–4: photosynthesis, respiration and energy/matter pathways; criterion 5: replicate graph/control defense, never a worksheet-only laboratory pass.
Human practical/safety review: Before use, the instructor must check the source, arithmetic, accessible format and approved assessment alternative; record the practical/safety review and any observation still required. Use data only unless a separate approved safe protocol and supervised equipment are available.
U4 · Receptors, pathway perturbations and feedback [signal-response]
Question: Which pathway order is consistent with the synthetic block/rescue results, and what evidence would challenge it?
Prerequisites: Read a controlled comparison, calculate means and distinguish a causal mechanism from a matching pattern.
Inputs and calibration: Supplied dataset, level tasks, checked answers and transfer in the existing unit. signal-activity.
Specific reading: OpenStax Biology 2e (2018), 9.1 Signaling Molecules and Cellular Receptors — Compare direct contact, local signals and long-distance signaling; identify receptor specificity. OpenStax Biology 2e (2018), 9.2 Propagation of the Signal — Trace receptor activation, phosphorylation cascades and second messengers. OpenStax Biology 2e (2018), 9.3 Response to the Signal — Compare changes in enzyme activity with changes in gene expression and discuss signal termination.
Materials
- Signal-activity table and movable reception/transduction/response cards.
- Graph paper and source diagrams; no live cells, drugs or biological samples.
Variables: Abstract ligand, receptor-block and downstream-activation conditions vary; reporter activity is measured at one fixed time.
Control/comparison: Vehicle is the baseline, ligand the stimulated comparison; propose independent viability and perturbation-specificity controls.
Sampling: The three independent preparations per condition are replicates. One endpoint per preparation does not reveal feedback dynamics.
Procedure and analysis
- Predict the pathway order and calculate each group mean.
- Graph the individual values; compare blockade and rescue against both controls.
- Draw feedback loops, name an alternative explanation and defend the unsuccessful-rescue transfer.
Produce a mechanism diagram and conditional evidence statement, not a diagnosis or a claim about all cellular responses.
Uncertainty: Reporter specificity, viable cell amount, off-target actions and absent time-course information limit inference.
Evidence to science criteria: Science criterion 2: pathway diagram and rescue argument; criterion 3: signed feedback loop; criterion 4: bounded dysregulation reasoning rather than personal medical conclusions.
Human practical/safety review: Before use, the instructor must check the source, arithmetic, accessible format and approved assessment alternative; record the practical/safety review and any observation still required. The activity is an abstract paper perturbation; no cell-culture or drug protocol is supplied.
U4 · Mitosis, DNA content and sampling assumptions [cycle-sampling]
Question: What can a fixed reference-cell snapshot support about division and what assumptions underlie phase-time estimates?
Prerequisites: Recognize chromosome-stage features, count fractions and distinguish sample units from fields within a slide.
Inputs and calibration: Supplied dataset, level tasks, checked answers and transfer in the existing unit. mitotic-counts; chromosome-model.
Specific reading: OpenStax Biology 2e (2018), 10.2 The Cell Cycle — Compare G1, S, G2 and mitosis; distinguish a chromosome counted by centromere from the number of DNA molecules. OpenStax Biology 2e (2018), 10.3 Control of the Cell Cycle — Read cyclin/CDK control and checkpoints; identify what must be checked before DNA replication and division progress. OpenStax Biology 2e (2018), 10.4 Cancer and the Cell Cycle — Connect checkpoint disruption to uncontrolled proliferation without treating a mitotic count as a clinical diagnosis. NobelPrize.org: The Nobel Prize in Physiology or Medicine 2001 — Read the 2001 recognition of Hartwell, Hunt and Nurse for cell-cycle regulators. Connect the recognized question to checkpoints; the summary does not supply our fictional root counts or authorize human tissue work.
Materials
- Supplied counts and chromosome-model cards; approved nonhuman reference images in the assigned reading.
- Calculator and a tally sheet with an explicit uncertain/unscorable category.
Variables: Classified cell stage is the response; sampling location and preparation quality may influence the observed fractions.
Control/comparison: Use a fixed stage-identification rule and a second blinded scoring pass; do not quietly force ambiguous cells into a phase.
Sampling: Nonoverlapping fields avoid duplicate cells but still share one root; additional independently sourced roots would support biological replication.
Procedure and analysis
- Predict chromosome/DNA counts before checking the model.
- Calculate phase fractions and annotate defining features in reference images without inventing observations.
- Apply the conditional time model, audit the arrest scenario and record remaining practical observation requirements.
Retain denominators, classification rules, uncertainty and a checkpoint explanation; separate reference-image skill from instrument handling.
Uncertainty: Stage ambiguity, field selection, root identity, synchronization and variable cell-cycle length limit generalization.
Evidence to science criteria: Science criterion 1: phase and DNA/chromosome reasoning; criteria 3–4: checkpoints and limitations; criterion 5: image identification with separately recorded supervised microscope evidence.
Human practical/safety review: Before use, the instructor must check the source, arithmetic, accessible format and approved assessment alternative; record the practical/safety review and any observation still required. Any prepared-slide focusing must be observed under a separate approved protocol; no human specimens or culture are used.
U5 · Independent assortment, probability and a checked chi-square test [mendel-counts]
Question: Are the synthetic phenotype counts unusually far from this prespecified independent-assortment model?
Prerequisites: Segregation and meiosis, probabilities summing to one, expected counts and basic squared differences.
Inputs and calibration: Supplied dataset, level tasks, checked answers and transfer in the existing unit. dihybrid-counts.
Specific reading: OpenStax Biology 2e (2018), 11.1 The Process of Meiosis — Trace homologous chromosomes through meiosis I and sisters through meiosis II; identify crossing over and independent assortment. OpenStax Biology 2e (2018), 12.1 Mendel’s Experiments and the Laws of Probability — Read Mendel’s experimental approach and the sum/product probability rules. Distinguish his historical observations from our synthetic counts. OpenStax Biology 2e (2018), 12.3 Laws of Inheritance — Study segregation, independent assortment and dihybrid crosses. State the assumptions before using a 9:3:3:1 ratio. NIST/SEMATECH e-Handbook: Critical Values of the Chi-Square Distribution — Use the upper-tail critical-value table: cumulative probability 0.95 gives 3.841 at df = 1 and 7.815 at df = 3. These supplied thresholds calibrate the tests here, not a p-value-as-proof rule.
Materials
- Dihybrid-counts, four gamete cards and a blank 4 × 4 cross grid.
- Calculator and supplied NIST df 1/df 3 critical values; no breeding or personal genetics.
Variables: Phenotype is categorical; parental genotypes and dominance/linkage rules define the null-model probabilities.
Control/comparison: Prespecify the cross, complete classification, α and expected ratio; do not fit the expectation to the observed counts.
Sampling: The data are independent model offspring, one count each. Real shared-family/environment or viability effects require scrutiny.
Procedure and analysis
- Construct gamete combinations and total the observed counts.
- Calculate all expected counts and four χ² contributions; check expected-frequency conditions.
- Compare to the correct critical reference, explain limits, then independently solve the monohybrid transfer.
Retain the cross, observed/expected table, contributions, degrees of freedom and a bounded fail-to-reject conclusion.
Uncertainty: Sampling variation and classification/viability bias have different meanings; χ² alone does not identify their biological cause.
Evidence to science criteria: Science criteria 1–2: meiosis, probability and χ² calculations; criterion 5: molecular/chromosomal conditions behind a ratio rather than an automatic whole-unit pass.
Human practical/safety review: Before use, the instructor must check the source, arithmetic, accessible format and approved assessment alternative; record the practical/safety review and any observation still required. Foundation uses counts and probability only; introduce inference only after the assumptions and critical reference are understood.
U5 · Non-Mendelian crosses and a fictional pedigree [inheritance-models]
Question: How do altered genotype-to-phenotype rules change cross and pedigree predictions without changing segregation?
Prerequisites: Gametes carry one allele per locus, conditional probability and clear nonhuman phenotype rules.
Inputs and calibration: Supplied dataset, level tasks, checked answers and transfer in the existing unit. inheritance-cards; pedigree-records.
Specific reading: OpenStax Biology 2e (2018), 12.2 Characteristics and Traits — Read incomplete dominance, codominance, sex-linked inheritance and multiple alleles. Distinguish a population’s possible alleles from an individual’s two copies at an autosomal locus. OpenStax Biology 2e (2018), 13.2 Chromosomal Basis of Inherited Disorders — Read pedigree logic and chromosome segregation changes as reference models. Do not analyze the learner’s family or infer a medical condition.
Materials
- Inheritance-cards, pedigree-records and blank cross grids.
- Colored allele cards or accessible text alternatives; no samples or family interviews.
Variables: Cross genotypes and stipulated dominance/sex-chromosome rules vary; predicted offspring phenotypes are outcomes.
Control/comparison: Write the phenotype rule before generating gametes; the ordinary segregation assumption is held fixed.
Sampling: These are probability models and a four-individual fictional pedigree, not sampled prevalence or real diagnostic evidence.
Procedure and analysis
- List gametes and genotype outcomes separately from phenotypes.
- Compute both conditional and overall X-linked probabilities with denominators.
- Deduce only forced pedigree genotypes, test changed assumptions and solve the fresh incomplete-dominance cross.
Retain cross grids and uncertainty sets for undetermined genotypes, including the conditional 2/3 result at honors level.
Uncertainty: Small pedigrees may fit multiple mechanisms; penetrance, mutation and classification assumptions are stipulated rather than verified.
Evidence to science criteria: Science criteria 2–4: solvable crosses and pedigree deductions; criterion 5: explicit allele-to-product explanation and model limitations.
Human practical/safety review: Before use, the instructor must check the source, arithmetic, accessible format and approved assessment alternative; record the practical/safety review and any observation still required. No personal genetic disclosure, human pedigree analysis or genetic counseling is part of this activity.
U5 · Linkage, recombination and environmental phenotype effects [linkage-environment]
Question: What can a testcross and a genotype-by-environment table each reveal, and what do they not measure?
Prerequisites: Alleles versus haplotypes, independent samples, testcrosses, means and genotype/phenotype distinctions.
Inputs and calibration: Supplied dataset, level tasks, checked answers and transfer in the existing unit. testcross-counts; phenotype-environment.
Specific reading: OpenStax Biology 2e (2018), 13.1 Chromosomal Theory and Genetic Linkage — Study the testcross logic and recombination maps. Explain why undetected multiple crossovers can make recombination fraction underestimate distance. OpenStax Biology 2e (2018), 12.2 Characteristics and Traits — Compare genotype, phenotype and environmental effects; not every phenotype difference is an allele-frequency change.
Materials
- Testcross-counts and phenotype-environment tables with their conditions.
- Calculator, chromosome cards and graph paper; no breeding or DNA manipulation.
Variables: Testcross gamete category is counted; in the second model genotype and temperature are explanatory factors and height is the response.
Control/comparison: Prespecify parental phase and tester genotype; hold age, resources and observation interval fixed in the growth comparison.
Sampling: One hundred independent model offspring and three independent plants per combination; categories and repeated height readings are not new replicates.
Procedure and analysis
- Classify recombinant haplotypes before adding counts.
- Compute the recombination estimate and plot genotype means across temperature.
- Separate genetic mapping from environmental response, audit assumptions and analyze the new testcross.
Retain a chromosome model, count denominator, map caveat and a graph that compares both factors without merging their interpretations.
Uncertainty: Multiple crossovers, viability and limited environmental sampling can alter inference; no physical DNA distance is measured.
Evidence to science criteria: Science criteria 1–3: meiosis, linkage and probability; criterion 5: genotype/environment mechanism; the pedigree criterion remains separately evidenced in inheritance-models.
Human practical/safety review: Before use, the instructor must check the source, arithmetic, accessible format and approved assessment alternative; record the practical/safety review and any observation still required. The supplied records are the complete paper alternative; no plant crosses or genetics procedures are directed.
U6 · Antiparallel copying and semiconservative evidence [replication-evidence]
Question: Which specified copying model matches the ideal density generations and correct strand directions?
Prerequisites: Base pairing, double strands, powers of two and 5′/3′ direction labels.
Inputs and calibration: Supplied dataset, level tasks, checked answers and transfer in the existing unit. replication-bands.
Specific reading: OpenStax Biology 2e (2018), 14.2 DNA Structure and Sequencing — Compare nucleotide linkage, complementary bases and antiparallel strand direction. OpenStax Biology 2e (2018), 14.3 Basics of DNA Replication — Read the Meselson–Stahl model comparison; identify what the density bands discriminate. OpenStax Biology 2e (2018), 14.4 DNA Replication in Prokaryotes — Trace helicase, topoisomerase, RNA primer, DNA polymerase and ligase at a replication fork. OpenStax Biology 2e (2018), 14.5 DNA Replication in Eukaryotes — Compare multiple origins and chromosome-end issues with the bacterial example; no laboratory protocol is assigned.
Materials
- Replication-bands, colored paper strands or tactile equivalents.
- Assigned fork and density-model figures; no isotopes, cells or DNA extraction.
Variables: Complete replication generation changes; the response is modeled heavy/hybrid/light duplex fraction.
Control/comparison: The generation-zero all-heavy model establishes the starting state; conservative and dispersive predictions are explicit alternatives.
Sampling: Fractions are ideal model outputs, not independent observed replicates or historical measurements.
Procedure and analysis
- Mark the two original strands and keep them identifiable during each doubling.
- Draw the replication fork and compare generations one and two with competing model predictions.
- Predict the fourth generation and audit band-detection and complete-round assumptions.
Retain strand lineage, synthesis arrows and a discriminating model comparison rather than only the word semiconservative.
Uncertainty: Real density assays have resolution, calibration and population-timing limits absent from this ideal table.
Evidence to science criteria: Science criterion 1: strand lineage and directional replication mechanism; criterion 5: limits of a molecular measurement model, separate from practical laboratory certification.
Human practical/safety review: Before use, the instructor must check the source, arithmetic, accessible format and approved assessment alternative; record the practical/safety review and any observation still required. This is exclusively model interpretation; it authorizes no isotope, culture or DNA procedure.
U6 · Template direction, RNA processing and translation [sequence-flow]
Question: Can the learner trace information from a direction-labeled DNA template through processed RNA to a peptide?
Prerequisites: Complementarity, 5′/3′ ends, triplet reading and cellular compartments.
Inputs and calibration: Supplied dataset, level tasks, checked answers and transfer in the existing unit. sequence-inputs; codon-key; rna-exons.
Specific reading: OpenStax Biology 2e (2018), 15.1 The Genetic Code — Use the RNA codon chart, including start, stop and degeneracy. A stop codon is not an amino acid. OpenStax Biology 2e (2018), 15.2 Prokaryotic Transcription — Track RNA polymerase reading a DNA template and producing RNA; compare the coding strand. OpenStax Biology 2e (2018), 15.3 Eukaryotic Transcription — Contrast nuclear transcription in the eukaryotic model with prokaryotic transcription. OpenStax Biology 2e (2018), 15.4 RNA Processing in Eukaryotes — Read the 5′ cap, poly-A tail, intron removal and alternative splicing. OpenStax Biology 2e (2018), 15.5 Ribosomes and Protein Synthesis — Trace ribosome initiation, tRNA anticodons, peptide elongation and release at stop.
Materials
- Sequence-inputs, codon-key and movable rna-exons cards.
- Pencil/highlighter or accessible text editor, with no biological samples.
Variables: Template orientation and retained exon set vary; predicted RNA and peptide are outputs.
Control/comparison: Keep the supplied start and standard-code convention fixed; use the coding strand as a cross-check, not as the polymerase template.
Sampling: These are short deterministic sequence models, not a sample of organism genomes or a prevalence study.
Procedure and analysis
- Mark strand ends and independently transcribe before revealing the supplied RNA.
- Read codons from the stated start through the first stop and compare exon choices.
- Explain cellular locations and solve the reversed-template transfer with both ends visible.
Retain direction-labeled DNA/RNA, spaced codons, peptide, stop handling and an explanation of processing/regulation.
Uncertainty: Real transcripts have untranslated regions, multiple starts, modifications and code exceptions omitted from this excerpt.
Evidence to science criteria: Science criterion 2: direction-correct transcription/translation and locations; criterion 3: RNA processing as regulation; criterion 4: frame-aware predictions rather than memorized central-dogma labels.
Human practical/safety review: Before use, the instructor must check the source, arithmetic, accessible format and approved assessment alternative; record the practical/safety review and any observation still required. This sequence reasoning does not demonstrate extraction, pipetting, sequencing or DNA manipulation.
U6 · Sequence changes, reading frames and bounded phenotype predictions [mutation-effects]
Question: Which peptide consequences follow from each specified short variant, and which effects remain unmeasured?
Prerequisites: Correct transcription direction, codon lookup, reading frames and the difference between molecular outcome and phenotype.
Inputs and calibration: Supplied dataset, level tasks, checked answers and transfer in the existing unit. mutation-sequences.
Specific reading: OpenStax Biology 2e (2018), 14.6 DNA Repair — Compare base substitutions, insertions/deletions, spontaneous errors, damage and repair; mutation does not arise because it would be useful. OpenStax Biology 2e (2018), 15.1 The Genetic Code — Use codon degeneracy and stop codons to distinguish synonymous, missense and nonsense consequences. OpenStax Biology 2e (2018), 13.2 Chromosomal Basis of Inherited Disorders — Distinguish short sequence variants from chromosome-number/structure changes; this activity does not supply a diagnostic chromosome bank.
Materials
- Mutation-sequences with the checked column initially covered; Unit 6 codon-key.
- Triplet cards or an accessible text editor; no actual sequence collection.
Variables: Only the stated synthetic sequence edit changes relative to the reference; the standard code and start position stay fixed.
Control/comparison: Translate the unchanged reference in the same frame before comparing variant products.
Sampling: Six deliberately chosen sequence examples illustrate mechanisms; they do not estimate mutation rates or effect frequencies.
Procedure and analysis
- Mark exact changed bases and convert coding DNA to RNA.
- Translate through the first stop, distinguishing frame preservation from sequence preservation.
- Compare to the public calibration, state unmeasured functional effects and solve the synonymous transfer.
Retain base-by-base changes, codons, peptide products and a context-dependent phenotype prediction with an alternative explanation.
Uncertainty: The short excerpt omits real expression, folding, repair, cellular environment and organism fitness measurements.
Evidence to science criteria: Science criteria 2 and 4: checked sequence/variant reasoning; criteria 3 and 5: expression controls and limits on phenotype claims.
Human practical/safety review: Before use, the instructor must check the source, arithmetic, accessible format and approved assessment alternative; record the practical/safety review and any observation still required. No human variant interpretation, disease prediction or genetic-engineering procedure is provided.
U6 · Prokaryotic and eukaryotic regulation at multiple levels [regulation-contrast]
Question: Which control level is consistent with each model pattern and which mechanisms remain unresolved?
Prerequisites: Transcription/translation distinction, ratios, zero denominators and the meaning of normalized measurements.
Inputs and calibration: Supplied dataset, level tasks, checked answers and transfer in the existing unit. lac-expression; expression-levels.
Specific reading: OpenStax Biology 2e (2018), 16.2 Prokaryotic Gene Regulation — Compare the lac repressor/operator with positive cAMP–CAP regulation and the repressible trp example. Do not use one on/off rule for every operon. OpenStax Biology 2e (2018), 16.3 Eukaryotic Epigenetic Gene Regulation — Compare accessible and less-accessible chromatin; distinguish epigenetic regulation from a changed DNA sequence. OpenStax Biology 2e (2018), 16.4 Eukaryotic Transcription Gene Regulation — Trace promoter, transcription factors and enhancer interactions. OpenStax Biology 2e (2018), 16.5 Eukaryotic Post-transcriptional Gene Regulation — Read alternative splicing and RNA stability, including small RNA effects. OpenStax Biology 2e (2018), 16.6 Eukaryotic Translational and Post-translational Gene Regulation — Separate translational control and protein degradation from transcription rate.
Materials
- Lac-expression and expression-levels tables; promoter/operator and chromatin diagrams from the readings.
- Calculator and pathway cards; no organisms, media or genetic material.
Variables: Model nutrient signals vary for lac; RNA and protein outputs are compared under equal gene copy/reference assumptions in the eukaryotic model.
Control/comparison: Keep reporter/reference calibration and viable sampled amount comparable; a zero baseline cannot support an ordinary fold ratio.
Sampling: These are illustrative endpoint means with no replicate distributions; do not manufacture error bars or significance tests.
Procedure and analysis
- Separate negative repressor control from positive activation in a diagram.
- Compute defined ratios and mark undefined zero-baseline comparisons.
- Compare regulation levels, propose discriminatory observations and solve the new equal-RNA case.
Retain operon and eukaryotic pathway models, calculations and at least one alternative mechanism for an endpoint pattern.
Uncertainty: RNA/protein half-lives, normalization stability and unmeasured viability can change the interpretation; causal regulation needs stronger design.
Evidence to science criteria: Science criterion 3: distinct prokaryotic/eukaryotic mechanisms; criterion 2: RNA versus protein; criteria 4–5: perturbation limits and measurement controls.
Human practical/safety review: Before use, the instructor must check the source, arithmetic, accessible format and approved assessment alternative; record the practical/safety review and any observation still required. Data interpretation is the approved-type alternative awaiting local review; no culture, drug or DNA manipulation is directed.
U6 · Gel, amplification and genome-evidence interpretation [biotech-interpretation]
Question: How do controls and scale calibration constrain a molecular-method interpretation without executing a procedure?
Prerequisites: Powers of two, measurement calibration, positive/negative controls; honors uses logarithmic interpolation.
Inputs and calibration: Supplied dataset, level tasks, checked answers and transfer in the existing unit. gel-ladder; gel-controls; pcr-model.
Specific reading: OpenStax Biology 2e (2018), 17.1 Biotechnology — Read PCR, gel electrophoresis and DNA sequencing conceptually. Use the figures to interpret controls and size; no experimental steps from the chapter are assigned. NHGRI: Human Genome Project (public overview) — Read the project overview and dated milestones. Distinguish a reference sequence from a full explanation of regulation, phenotype or an individual’s health.
Materials
- Gel-ladder, gel-controls and pcr-model cards; ruler or accessible supplied measurements.
- Calculator with square root/logarithms at honors level and the public source figures.
Variables: Migration distance and model cycle number vary; estimated fragment length and ideal copy count are outputs.
Control/comparison: Size ladder, known positive reference and no-template negative control are all supplied and serve distinct purposes.
Sampling: The ladder and two run cards are modeled records, not replicated method-validation data or real sample-identification evidence.
Procedure and analysis
- Check controls before making any sample claim.
- Use the ladder bracket and appropriate linear/log model; compute ideal target copies separately.
- State what remains unmeasured, discuss reference-genome limits and defend the changed-distance transfer.
Retain control decisions, units, interpolation and amplification arithmetic, plus a distinction among size, amount and sequence.
Uncertainty: Band width, gel conditions, detection limits and nonideal amplification can alter estimates; no experimental precision is inferred.
Evidence to science criteria: Science criterion 5: method interpretation, calibration and ethics; criteria 1 and 3: replication/expression distinctions. Hands-on method certification requires separate observed evidence.
Human practical/safety review: Before use, the instructor must check the source, arithmetic, accessible format and approved assessment alternative; record the practical/safety review and any observation still required. No DNA manipulation instructions, human samples, unknown microbes, electrical setup or chemicals are supplied.
U7 · Selection, random drift and measured generational change [selection-drift]
Question: How do specified reproductive differences and random small-population draws produce different frequency predictions?
Prerequisites: Fractions, heritable versus acquired change, reproductive contribution and independent samples.
Inputs and calibration: Supplied dataset, level tasks, checked answers and transfer in the existing unit. haploid-selection; drift-replicates.
Specific reading: OpenStax Biology 2e (2018), 18.1 Understanding Evolution — Read evidence and common misconceptions. Evolution describes population change and common ancestry, not individuals trying to change. OpenStax Biology 2e (2018), 19.2 Population Genetics — Compare selection, gene flow and genetic drift; drift is a sampling effect, not a synonym for any change. OpenStax Biology 2e (2018), 19.3 Adaptive Evolution — Compare relative fitness, directional/stabilizing/disruptive selection and artificial selection. Fitness concerns reproductive contribution in context, not physical strength.
Materials
- Haploid-selection and drift-replicates records; allele cards if modeling by hand.
- Calculator and axes labeled generation versus allele frequency.
Variables: Relative descendant contribution differs between alleles in the selection model; only random sample composition varies in drift draws.
Control/comparison: Use equal reproductive weights for the no-selection comparison; keep initial frequency, mutation and migration assumptions explicit.
Sampling: Four drift populations are independent fictional draws; alleles within one population are not four separate experiments.
Procedure and analysis
- Calculate initial and predicted descendant allele frequencies.
- Plot all drift draws rather than selecting the one that matches a preferred story.
- Contrast selection, drift and human selection, then solve the equal-weight transfer.
Retain counts, denominators and an environment-specific mechanism, distinguishing expected from realized change.
Uncertainty: Small modeled samples show variability but do not quantify real selection strength or prove a cause in a wild population.
Evidence to science criteria: Science criteria 1 and 5: heritable variation/reproduction without teleology; criterion 2: quantitative evidence and alternative mechanisms rather than a progress ladder.
Human practical/safety review: Before use, the instructor must check the source, arithmetic, accessible format and approved assessment alternative; record the practical/safety review and any observation still required. Use cards or supplied data only; no live breeding, capture or organism selection is required.
U7 · Hardy–Weinberg expectations and genotype departures [equilibrium-audit]
Question: Can genotype proportions depart from an equilibrium reference while measured allele frequencies stay the same?
Prerequisites: Diploid allele counts, probability squares and, for honors, goodness-of-fit assumptions and degrees of freedom.
Inputs and calibration: Supplied dataset, level tasks, checked answers and transfer in the existing unit. genotype-snapshots.
Specific reading: OpenStax Biology 2e (2018), 19.1 Population Evolution — Read Hardy–Weinberg conditions and allele/genotype frequencies. Separate a null expectation from observed evidence of change. NIST/SEMATECH e-Handbook: Critical Values of the Chi-Square Distribution — Use the supplied upper-tail α = 0.05 threshold 3.841 at df = 1. The genotype example estimates one allele frequency from the sample, reducing df by one.
Materials
- Genotype-snapshots with blank observed/expected columns.
- Calculator, supplied df 1 critical value and the Hardy–Weinberg reading.
Variables: Generation sample and genotype class are recorded; allele frequencies and expected counts are derived.
Control/comparison: Use the same locus, reliable classification and predeclared conditions; fit p transparently rather than assuming it changed.
Sampling: Each row is a separate fictional independent diploid sample; relatedness, population mixture and genotype error require checks in real work.
Procedure and analysis
- Count both alleles with the 2N denominator in each sample.
- Compute model genotype expectations and, at honors level, χ² with adjusted df.
- State a bounded conclusion and alternative mechanism, then solve the matching-proportions transfer.
Retain p/q calculations, observed/expected counts, conditions and explicit separation of genotype departure from measured temporal change.
Uncertainty: Sampling error, relatedness, structure and misclassification are not ruled out by a large statistic; one locus is not a whole genome.
Evidence to science criteria: Science criterion 3: equilibrium calculation with assumptions; criteria 1 and 5: no selection-as-proof or genotype-departure shortcut; criterion 2: evidentiary limits.
Human practical/safety review: Before use, the instructor must check the source, arithmetic, accessible format and approved assessment alternative; record the practical/safety review and any observation still required. These are fictional nonhuman genotypes; do not collect personal genetic or family information.
U7 · Sequence evidence, branching ancestry and reproductive barriers [phylogeny-speciation]
Question: Which branching relationship and barrier classifications are supported by the limited supplied evidence?
Prerequisites: Aligned positions, shared versus unique characters, branching diagrams and the meaning of reproductive isolation.
Inputs and calibration: Supplied dataset, level tasks, checked answers and transfer in the existing unit. phylogeny-sequences; barrier-cases.
Specific reading: OpenStax Biology 2e (2018), 20.2 Determining Evolutionary Relationships — Read homologous traits, molecular comparisons and phylogenetic inference; sister tips share an ancestor and are not ancestors of each other. OpenStax Biology 2e (2018), 18.1 Understanding Evolution — Connect fossil, anatomical and molecular evidence; distinguish homology from convergence. OpenStax Biology 2e (2018), 18.2 Formation of New Species — Compare allopatric/sympatric pathways and prezygotic/postzygotic barriers. OpenStax Biology 2e (2018), 18.3 Reconnection and Speciation Rates — Read reinforcement, hybrid zones and limits of simple species models.
Materials
- Phylogeny-sequences, barrier-cases and blank branch diagrams.
- Highlighters or accessible column-indexed text; no specimen collection.
Variables: Lineage and homologous sequence position define comparisons; barrier evidence is classified by when it acts.
Control/comparison: Use the stipulated outgroup and aligned homologous sites; do not infer ancestry just from one similar function.
Sampling: One synthetic locus and three case records are not independent confirmations across a genome or species range.
Procedure and analysis
- Number aligned columns and mark shared derived states relative to O.
- Count pairwise differences, draw the tree and rotate a sister branch.
- Classify barriers, identify missing evidence and solve the fresh topology case.
Retain site-by-site evidence, tree topology and barrier conditions, with no unsupported dates or ladder interpretation.
Uncertainty: Short loci, convergence, model choice and sampling can affect tree inference; these cards do not settle real species boundaries.
Evidence to science criteria: Science criteria 2 and 4: molecular evidence, branching tree and isolation logic; criterion 5: explicit correction of progress/ancestor misconceptions.
Human practical/safety review: Before use, the instructor must check the source, arithmetic, accessible format and approved assessment alternative; record the practical/safety review and any observation still required. Source images/models and fictional sequences are sufficient; no DNA sampling or breeding is authorized.
U8 · Trophic production and carbon, nitrogen and water ledgers [energy-matter-ledgers]
Question: Can a learner reconcile trophic energy transfers with three distinct bounded material cycles?
Prerequisites: Stocks versus rates, compatible energy/area/time units, percentages and material conservation.
Inputs and calibration: Supplied dataset, level tasks, checked answers and transfer in the existing unit. production-budget; matter-budgets.
Specific reading: OpenStax Biology 2e (2018), 46.2 Energy Flow through Ecosystems — Read GPP/NPP, trophic transfer and the distinction between biomass stocks and energy-production rates. OpenStax Biology 2e (2018), 46.3 Biogeochemical Cycles — Trace carbon, nitrogen and water reservoirs/processes; name biological and physical routes rather than drawing one generic cycle.
Materials
- Production-budget and matter-budgets with blank flow diagrams.
- Calculator and the source carbon, nitrogen and water figures.
Variables: Production at successive trophic levels and inputs/outputs of a defined reservoir are modeled.
Control/comparison: Hold area, time interval, production definition and reservoir boundary constant before comparing ratios or balances.
Sampling: Single synthetic annual budgets are not replicated ecosystems or observed trend evidence.
Procedure and analysis
- Label stocks and flows and calculate NPP before transfer ratios.
- Draw separate carbon, nitrogen and water routes including named transformations.
- Reconcile balances, assess optional uncertainty bounds and analyze the fresh energy system.
Retain units, multiplicative transfer, separate cycle diagrams and a written explanation of energy flow versus matter cycling.
Uncertainty: Boundary omissions and uncertain fluxes change budgets; no exact universal transfer percentage or measurement precision is established.
Evidence to science criteria: Science criteria 1–2: approximate transfer and all three material cycles; criterion 5: quantitative evidence with boundaries and uncertainty.
Human practical/safety review: Before use, the instructor must check the source, arithmetic, accessible format and approved assessment alternative; record the practical/safety review and any observation still required. No ecosystem sampling, nutrient addition or environmental manipulation is required.
U8 · Independent quadrats, growth limits and recapture assumptions [population-sampling]
Question: How do sampling design and model assumptions constrain density and next-generation estimates?
Prerequisites: Area, density, random sampling, means/variation and a one-step population model.
Inputs and calibration: Supplied dataset, level tasks, checked answers and transfer in the existing unit. quadrat-plants; growth-start; paper-recapture.
Specific reading: OpenStax Biology 2e (2018), 45.1 Population Demography — Compare quadrat, transect and mark-recapture approaches; state the sampling frame and closed-population assumptions. OpenStax Biology 2e (2018), 45.3 Environmental Limits to Population Growth — Compare exponential and logistic growth; distinguish the continuous model from this explicit one-step approximation. OpenStax Biology 2e (2018), 45.4 Population Dynamics and Regulation — Distinguish density-dependent feedback from density-independent disturbances; carrying capacity can change with conditions.
Materials
- Supplied quadrat and recapture records plus growth-start.
- A paper grid and tokens or accessible virtual equivalents; calculator.
Variables: Location is the sampling dimension; counts per area are responses. Growth parameters and token sampling are separate explicitly modeled inputs.
Control/comparison: Fix quadrat size/boundary rules and sampled habitat frame; hold r/K only for the stated step and keep token marks persistent.
Sampling: Four distinct random quadrats are independent units in the toy model; recounts and unequal-area strata require separate handling.
Procedure and analysis
- Compute densities using summed count/summed area and retain zeros.
- Calculate and compare the two growth steps, then the closed-token recapture estimate.
- Audit field selection and zero recaptures; optionally sketch a non-destructive approved photo-grid observation plan.
Retain sampling map or synthetic label, unit-bearing density, selected-level variation and conditional model predictions.
Uncertainty: Patchiness, detection, limited plots, open-population movement and changing K/r constrain extrapolation.
Evidence to science criteria: Science criterion 3: growth and density-dependence; criterion 5: sampling/variation and model limits. Field technique is not certified by supplied counts.
Human practical/safety review: Before use, the instructor must check the source, arithmetic, accessible format and approved assessment alternative; record the practical/safety review and any observation still required. Default to the paper grid; any optional ground observation must be accessible, non-destructive and preapproved, with no wildlife capture.
U2 · Cell walls, membranes and pressure balance [cell-wall-pressure]
Question: How can a cell wall support a water-potential balance without replacing selective membrane transport?
Prerequisites: Distinguish solute potential from pressure and identify the plasma membrane separately from the wall.
Inputs and calibration: Supplied dataset, level tasks, checked answers and transfer in the existing unit. wall-potentials.
Specific reading: OpenStax Biology 2e (2018), 4.3 Eukaryotic Cells — Read The Cell Wall and the central vacuole discussion. Compare support outside the membrane with selective passage across the membrane. OpenStax Biology 2e (2018), 5.2 Passive Transport — Read osmosis and tonicity in walled and unwalled cells. A rigid wall can resist expansion but does not eliminate an osmotic gradient.
Materials
- Printed potential table and calculator, or an accessible spreadsheet.
- Assigned cell-wall and osmosis reference diagrams; no biological preparation.
Variables: Compare wall/pressure state and bath potential while retaining the supplied cell-solute value for each initial state.
Control/comparison: The equal-total turgid case is the reference balance; no randomized treatment experiment is represented.
Sampling: Three constructed states are examples, not independent measurements of one organism or all cell types.
Procedure and analysis
- Sketch wall, membrane and bath as separate components.
- Calculate totals before predicting initial movement.
- Check the transfer balance and list the missing dynamic variables.
Retain signed sums, movement arrows and a mechanism explanation linking wall support with membrane selectivity.
Uncertainty: The values are exact for classroom arithmetic; real permeability, concentration and mechanical uncertainty are not measured here.
Evidence to science criteria: Science criteria 2 and 5: signed potential calculations, membrane-versus-wall explanation, transfer balance and an explicit model limitation.
Human practical/safety review: Before use, the instructor must check the source, arithmetic, accessible format and approved assessment alternative; record the practical/safety review and any observation still required. Paper calculations assess reasoning only, not microscopy or osmotic-treatment technique.
U2 · Organism water budgets without equalizing the environment [organism-osmoregulation]
Question: Can an organism maintain a stable water volume while its internal osmolarity differs from the surrounding water?
Prerequisites: Read signed flux ledgers and distinguish water movement, osmolarity, and active ion transport.
Inputs and calibration: Supplied dataset, level tasks, checked answers and transfer in the existing unit. fish-gradients; fish-water-budgets.
Specific reading: OpenStax Biology 2e (2018), 41.1 Osmoregulation and Osmotic Balance — Read osmotic balance, electrolyte transport and osmoregulators. Distinguish a maintained internal environment from simply matching external salinity.
Materials
- Supplied gradients and water-budget cards with the common period and organism boundary.
- Calculator and an annotated osmoregulation reference diagram; no animals or water treatments.
Variables: Compare environment and the regulated flux terms while keeping each model ledger boundary and daily units fixed.
Control/comparison: Use each balanced ledger as its own arithmetic reference; changed urine is a thought experiment, not an intervention.
Sampling: Two representative synthetic models do not estimate variation among fish or prove a species-specific response.
Procedure and analysis
- Mark the osmotic direction from the supplied gradients.
- Calculate both net balances and the changed-output case.
- Add the separate ion ledger and explain why water and ion balance differ.
Submit two water balances, the counterfactual and a mechanistic explanation with separate ion and water accounting.
Uncertainty: Real fluxes depend on body mass, temperature, acclimation and species; these are omitted rather than estimated.
Evidence to science criteria: Science criteria 2 and 5: gradient interpretation, daily water/ion balances, energy-dependent transport explanation and qualified survival inference.
Human practical/safety review: Before use, the instructor must check the source, arithmetic, accessible format and approved assessment alternative; record the practical/safety review and any observation still required. Do not expose animals to changed salinity or infer veterinary care from this worksheet.
U3 · Conserved glycolysis as one line of ancestry evidence [conserved-metabolism]
Question: What does conserved biochemical bookkeeping support, and what additional evidence is required for an ancestry inference?
Prerequisites: Distinguish gross and net ATP, carbon bookkeeping, homologous structures and independent observations.
Inputs and calibration: Supplied dataset, level tasks, checked answers and transfer in the existing unit. conserved-glycolysis.
Specific reading: OpenStax Biology 2e (2018), 7.2 Glycolysis — Read glycolysis location, investment and payoff. Compare the conserved pathway with independent sequence/structure evidence rather than deriving ancestry from arithmetic alone. OpenStax Biology 2e (2018), 20.2 Determining Evolutionary Relationships — Read molecular comparisons and homologous characters; shared function is not by itself a complete phylogenetic argument.
Materials
- The four-row reference table and the supplied alternative-pathway ledger.
- Assigned glycolysis and phylogeny sections; pencil or accessible diagram software.
Variables: Compare pathway location and net products across selected representatives without treating the labels as randomized treatments.
Control/comparison: The reference pathway supplies a common accounting convention; the alternative tests whether yield alone discriminates mechanisms.
Sampling: These selected reference examples are not a random sample of biodiversity and are not independent measurements.
Procedure and analysis
- Calculate net ATP and carbon balance.
- Separate reference facts from ancestral inferences.
- Evaluate the alternative and propose independent molecular comparisons.
Retain the ledger and a source-linked claim/evidence/limitation paragraph rather than an invented ancestry probability.
Uncertainty: The reference omits metabolic diversity, evolutionary rates and horizontal transfer; no numerical ancestry certainty is justified.
Evidence to science criteria: Science criteria 3 and 4: energy bookkeeping and a bounded explanation connecting conserved processes with independent evolutionary evidence.
Human practical/safety review: Before use, the instructor must check the source, arithmetic, accessible format and approved assessment alternative; record the practical/safety review and any observation still required. No culture, metabolic assay or ancestral reconstruction experiment is performed.
U7 · From enzyme variation to environment-dependent reproductive output [molecule-fitness]
Question: How can a molecular variant have context-dependent reproductive consequences without being universally beneficial?
Prerequisites: Understand inherited molecular variation, means, founders and relative reproductive output within a defined environment.
Inputs and calibration: Supplied dataset, level tasks, checked answers and transfer in the existing unit. enzyme-fitness.
Specific reading: OpenStax Biology 2e (2018), 19.3 Adaptive Evolution — Read relative fitness and selection on heritable variation. Fitness is reproductive contribution in a context, not a universal measure of strength. OpenStax Biology 2e (2018), 6.5 Enzymes — Connect protein variation and environmental conditions to measured reaction rate; rate alone does not establish whole-organism fitness.
Materials
- Printed paired assay/offspring table and calculator or accessible spreadsheet.
- Selection and enzyme reference sections; no organisms, culture or manipulation.
Variables: Compare variant and temperature while using the supplied founder count and common population interval for normalization.
Control/comparison: The reference variant is compared within each environment; other genetic/expression differences are potential confounders to audit.
Sampling: Three synthetic independent populations per condition illustrate replicate design; no real variance or causal effect has been measured.
Procedure and analysis
- Compare the molecular and reproductive columns separately.
- Compute mean output per founder and within-environment relative values.
- Explain the reversal and design a controlled follow-up on paper.
Retain denominators, environment-specific comparisons and a molecular-to-phenotype-to-fitness explanation.
Uncertainty: Small synthetic groups do not establish a population parameter, long-term evolution or an experimentally validated causal pathway.
Evidence to science criteria: Science criteria 1 and 2: connect heritable molecular variation with conditional reproductive outcomes using computed comparisons, controls and transfer.
Human practical/safety review: Before use, the instructor must check the source, arithmetic, accessible format and approved assessment alternative; record the practical/safety review and any observation still required. The proposed design does not authorize a culture or selection experiment.
U7 · Shared eukaryotic features and the limits of a trait table [eukaryote-evidence]
Question: What shared eukaryotic evidence supports a history hypothesis, and what cannot be concluded from this selected matrix?
Prerequisites: Identify nuclear and organelle features in reference diagrams and distinguish homology from simple resemblance.
Inputs and calibration: Supplied dataset, level tasks, checked answers and transfer in the existing unit. eukaryote-features.
Specific reading: OpenStax Biology 2e (2018), 4.3 Eukaryotic Cells — Compare nuclear organization, internal compartments, mitochondria and chloroplasts in the reference figures. Use cell type and life stage, not universal organelle assumptions. OpenStax Biology 2e (2018), 20.2 Determining Evolutionary Relationships — Read homology and molecular comparisons; distinguish an identification matrix from independently supported ancestry evidence.
Materials
- The source figures and four-row reference matrix.
- Colored pencils or an accessible branching-diagram tool; no slide preparation required.
Variables: Compare defined cellular features across representative types, not an experimental manipulation or a complexity score.
Control/comparison: Keep the same definition of each feature across examples; examine exceptions using the same criteria rather than changing the rule.
Sampling: Four chosen reference examples are not a random sample of species, cells, or independent evolutionary events.
Procedure and analysis
- Annotate shared and differing features.
- Distinguish reference observations from an ancestry inference.
- Apply the specialist-cell transfer and propose an independent molecular comparison.
Retain trait counts and a written argument using branching relationships and evidence limits rather than an ancestry percentage.
Uncertainty: Lineage losses, convergence, endosymbiosis and missing molecular context limit conclusions from a few visible characters.
Evidence to science criteria: Science criteria 2 and 5: source-based shared-feature reasoning, an explicit exception analysis, and a branching-history transfer argument.
Human practical/safety review: Before use, the instructor must check the source, arithmetic, accessible format and approved assessment alternative; record the practical/safety review and any observation still required. Reference interpretation does not certify microscopy or phylogenetic reconstruction skill.
U7 · Normalize speciation opportunities and distinguish trait tempo [speciation-tempo]
Question: How do exposure and fossil sampling alter claims about evolutionary tempo and the frequency of lineage splitting?
Prerequisites: Read elapsed time, rates, uncertainty and branching histories without confusing a taxon label with a measured isolation event.
Inputs and calibration: Supplied dataset, level tasks, checked answers and transfer in the existing unit. speciation-exposure; fossil-tempo.
Specific reading: OpenStax Biology 2e (2018), 18.3 Reconnection and Speciation Rates — Read reconnection and varying rates. Separate a lineage-splitting rate from the speed of a morphological change or gaps in a fossil record.
Materials
- The two supplied simulation/reference tables and calculator.
- Speciation-rate reading and graph paper or an accessible plotting tool.
Variables: Compare event counts per lineage exposure and trait changes per elapsed time as two different response measures.
Control/comparison: Use the same event definition and detection assumptions within the two model groups; they are not randomized real populations.
Sampling: The three-million-year gap is deliberately unsampled; do not add invented intermediate measurements or replicate lineages.
Procedure and analysis
- Normalize event counts by exposure.
- Plot trait length and compute interval slopes.
- Evaluate the burst claim and calculate the new normalized transfer rate.
Submit both rate types with their different units, a graph retaining the gap, and a cautious interpretation of tempo.
Uncertainty: No confidence interval, detection probability or true diversification rate is estimated by these synthetic summaries.
Evidence to science criteria: Science criteria 4 and 5: normalized rate comparison, trait graph, distinction between morphology and lineage splitting, and a source-linked sampling critique.
Human practical/safety review: Before use, the instructor must check the source, arithmetic, accessible format and approved assessment alternative; record the practical/safety review and any observation still required. No fossil collection or claims of newly observed speciation are required.
U7 · Compare origin-of-life evidence without turning ingredients into organisms [origin-evidence]
Question: Which origin-of-life claims are supported by these source records, and which require evidence not supplied here?
Prerequisites: Distinguish molecules from living systems, a hypothesis from a reconstruction, and ages before present from elapsed intervals.
Inputs and calibration: Supplied dataset, level tasks, checked answers and transfer in the existing unit. origin-evidence-records; origin-time-anchors.
Specific reading: NASA (2025): Asteroid Bennu Sample Reveals Mix of Life’s Ingredients — Read the opening finding and the distinction between organic ingredients and evidence of life. Identify the sample-return and contamination-control context. NobelPrize.org: Chemistry 1989 press release on catalytic RNA — Read the 1989 press-release summary. Explain why RNA catalysis is relevant to an RNA-world hypothesis but is not a complete recreation of the first life. USGS: Age of the Earth — Read why radiometric ages and meteorites constrain Earth history. Distinguish an age bound from the duration or mechanism of an origin process.
Materials
- The three source evidence cards and the explicitly supplied chronology scenario.
- NASA, Nobel and USGS assigned sections; calculator and comparison organizer.
Variables: Compare evidence type and question addressed, not a single experimental variable or a ranking of scientific institutions.
Control/comparison: Check every claim against what the named source actually reports; keep an explicit unsupported-claim column.
Sampling: The three selected records are unlike evidence types, not biological replicates or an exhaustive survey of origin research.
Procedure and analysis
- Identify observation, model and inference on each card.
- Compute the scenario interval and explain its limited meaning.
- Evaluate a new dated record and name missing evidence for a full mechanism.
Produce a source-linked comparison and interval calculation while keeping precursor chemistry, catalytic capability and dating distinct.
Uncertainty: Preservation, contamination, dating error and competing interpretations would need separate evaluation; exact classroom values do not remove those issues.
Evidence to science criteria: Science criteria 2 and 5: evidence classification, conditional chronology, comparison of hypotheses and a defensible statement of what remains unknown.
Human practical/safety review: Before use, the instructor must check the source, arithmetic, accessible format and approved assessment alternative; record the practical/safety review and any observation still required. This activity uses source records only; no prebiotic chemistry, radiation or culture experiment is authorized.
U8 · Geological and meteorological disruptions with comparison limits [physical-disturbance]
Question: How can volcanic and climate-related disturbances alter biological systems, and what does the supplied comparison fail to isolate?
Prerequisites: Distinguish percentage-point change from relative percent change, and a nonrandom comparison from a controlled experiment.
Inputs and calibration: Supplied dataset, level tasks, checked answers and transfer in the existing unit. ash-cover; upwelling-response.
Specific reading: USGS: Ecological and geological responses to the 1980 Mount St. Helens eruption — Read the USGS abstract on disturbance zones, survivor legacies and recovery after Mount St. Helens. It reports a complex history, not uniform destruction of all life. NOAA: What are El Niño and La Niña? — Read how weakened upwelling changes nutrients and marine food webs during El Niño; distinguish the mechanism from a particular two-row classroom record.
Materials
- The fictional equal-area plot and matched-context ocean tables.
- Assigned USGS/NOAA readings and calculator or spreadsheet; no visit to a hazard site.
Variables: Compare cover through time across ash/reference plots and environmental/production indices across two modeled ocean states.
Control/comparison: Reference plots supply a background comparison, not proof that all other conditions were identical or that allocation was random.
Sampling: Three distinct synthetic plots per group and two aggregate ocean states cannot establish a general field effect or all recovery trajectories.
Procedure and analysis
- Record each within-plot difference and its units.
- Calculate the group/adjusted changes and the separate ocean percentage.
- Connect mechanisms to sources and design a non-hazardous further-data comparison.
Retain a difference table, transparent denominators, a source-based mechanism and alternative explanations.
Uncertainty: No sampling error, spatial independence or causal effect has been measured; synthetic inputs demonstrate analysis only.
Evidence to science criteria: Science criteria 4 and 5: disturbance mechanisms, checked comparisons with correct units, reference limits and a qualified recovery prediction.
Human practical/safety review: Before use, the instructor must check the source, arithmetic, accessible format and approved assessment alternative; record the practical/safety review and any observation still required. No eruption, storm, ash-sampling, ocean excursion or wildlife manipulation is part of this task.