Grade 9 · printable course

Biology: Systems, Structure, and Change

Grade 9, Volume 2 · 500 pages · 53 lessons · PDF, print at home

A full-year, on-level Biology course for a homeschool learner working one-on-one with a parent through an adaptive learning app. The course moves from the chemistry of life through cell structure and energy transformation, into genetics, evolution, and ecology, closing with human body systems as an applied synthesis. Each unit is built around a real named phenomenon or dataset, uses explicit instruction for first acquisition followed by guided inquiry, and carries prior units forward through cumulative retrieval and spaced assessment rather than treating topics as closed chapters. The adaptive app supplies daily low-stakes retrieval items and mastery-paced practice; the parent delivers explicit instruction, worked examples, and the discussion-based checks that the app cannot score. This volume holds units 6 to 11: Evolution by Natural Selection; Ecosystem Structure: Energy and Matter Flow; Population and Community Ecology; Human Body Systems I: Nutrient Processing and Defense; Human Body Systems II: Coordination and Control; Capstone: Building an Evidence-Based Biological Argument.

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What is inside

Every unit and lesson in this book, in order. The same lessons are taught online at lettersanddevotion.com, so a family can move between paper and screen.

Biology: Systems, Structure, and Change

53 lessons · try a lesson online free

Unit 6: Evolution by Natural Selection8 lessons
  1. 46.The timing of heritable variation relative to a selection pressure
  2. 47.The distinction between allele-frequency change and allele creation
  3. 48.The structural criterion distinguishing homology from analogy
  4. 49.Convergent multi-line evidence for evolutionary relationship (fossil, anatomical, molecular)
  5. 50.The discrimination between natural selection and genetic drift as explanations for allele frequency change
  6. 51.Criteria for a species boundary (reproductive isolation) and sufficiency of evidence for speciation claims
  7. 52.The definitions of genetic drift, bottleneck effect, and founder effect
  8. 53.Argument construction ruling out a named alternative mechanism using dataset-specific evidence
Unit 7: Ecosystem Structure: Energy and Matter Flow8 lessons
  1. 54.The 10% energy transfer rule between trophic levels
  2. 55.The causal link between cellular respiration's energy loss and the ecosystem-level 10% rule
  3. 56.Food chain vs. food web as representational models of energy flow
  4. 57.The carbon cycle as conservation of matter across biosphere, atmosphere, ocean, and geosphere reservoirs
  5. 58.Structural similarities and differences between the carbon and nitrogen biogeochemical cycles
  6. 59.Energy-ceiling math as a constraint on ecosystem-change sustainability
  7. 60.The generality of one-directional energy loss independent of the specific energy source
  8. 61.Predicted redistribution of energy flow following removal of a species from a food web
Unit 8: Population and Community Ecology8 lessons
  1. 62.Exponential vs. logistic population growth curve shapes and the rate-of-change feature that distinguishes them
  2. 63.Carrying capacity and the mechanism by which growth rate declines as population approaches it
  3. 64.Density-dependent versus density-independent limiting factors
  4. 65.Negative feedback structure as a scale-general mechanism, compared across cell/organism and population scale
  5. 66.Exploitative versus interference interspecific competition, inferred from population data rather than observed behavior
  6. 67.Ecological resilience versus lasting community shift, evaluated from a multi-year disturbance dataset
  7. 68.Causal argument for a population inflection point, defended against a genuine alternative explanation
  8. 69.Core population-ecology vocabulary (exponential growth, logistic growth, carrying capacity, density-dependent/independent factor)
Unit 9: Human Body Systems I: Nutrient Processing and Defense10 lessons
  1. 70.Digestive organ structure and the macromolecule class each organ's enzymes target
  2. 71.Sequence of the heart-lung-body circulatory loop and the location of gas exchange
  3. 72.Enzyme-substrate specificity applied to digestive enzymes
  4. 73.Coupling of respiratory/circulatory structure to cellular respiration's oxygen requirement
  5. 74.Self/non-self recognition as the organizing function of the immune system
  6. 75.Antibiotic resistance as natural selection on existing variation
  7. 76.Organ-system malfunction sorted by system and level of organization
  8. 77.Cross-unit diagnostic reasoning applied to a novel clinical scenario
  9. 78.Structural similarity between checkpoint failure and self/non-self recognition failure
  10. 79.Cross-text comparison of clinical/scientific findings on organ-system disorders
Unit 10: Human Body Systems II: Coordination and Control11 lessons
  1. 80.Neuron structure (dendrite, axon, cell body, myelin sheath, axon terminal)
  2. 81.The sequence of ion movements that constitutes an action potential
  3. 82.Ion movement across the neuron membrane producing an action potential
  4. 83.Electrical-to-chemical signal conversion at the synapse
  5. 84.Correspondence between the sensor/control-center/effector labels and the specific textual description of each role
  6. 85.Structural and functional differences between nervous and endocrine signaling
  7. 86.Sensor-control center-effector structure of a negative feedback loop
  8. 87.Fault localization within a novel negative feedback loop
  9. 88.Metabolic (ATP) demand of nerve and muscle tissue
  10. 89.The relationship between apparent output stability and active regulatory cost in a feedback system
  11. 90.Classification of coordination responses as nervous vs. endocrine based on structural features
Unit 11: Capstone: Building an Evidence-Based Biological Argument8 lessons
  1. 91.The four explanatory frames as applied in a worked example case
  2. 92.The four explanatory frames applied to novel, confusable cases
  3. 93.The distinguishing mechanism features between two competing explanatory frames for one case
  4. 94.An unresolved real-world biological case and its connection to specific prior-unit content
  5. 95.A written evidence-based biological argument with a ruled-out alternative
  6. 96.Integration of a previously-uncited prior unit's content into a live defense of a biological argument
  7. 97.The distinction between correlational data and causal mechanism in the chosen case's evidence
  8. 98.Definitions and worked examples of the four explanatory frames

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