C. Natural Systems
C.3 Living Systems (Biology)
Course description
- Cell theory. Start from Robert Hooke's 1665 Micrographia, where he coined "cell" while looking at cork, and Antonie van Leeuwenhoek's discovery of microorganisms in the 1670s. Schleiden and Schwann's cell theory (1838–39) held that all organisms are made of cells; the further claim that cells arise only from other cells is Robert Remak's, published in 1852 and popularized, without full credit to Remak, by Rudolf Virchow in 1855. OpenStax Biology 2e or Campbell Biology cover cell structure and basic physiology; look at onion skin or pond water under a microscope if you can.
- Genetics and evolution. Gregor Mendel's pea-plant experiments (1866) revealed particulate inheritance before anyone had the word "gene." Darwin and, independently, Alfred Russel Wallace proposed natural selection in joint papers read to the Linnean Society in 1858, entering a debate over the transmutation of species that Lamarck and Robert Chambers's anonymously published Vestiges of the Natural History of Creation (1844) had already opened; Darwin's On the Origin of Species (1859) is worth reading at least in its introduction and conclusion. R. A. Fisher's 1936 statistical analysis argued that Mendel's published pea-count data fit the predicted ratios suspiciously well, a dispute over how to read the data that is still argued and connects directly to B.2. The modern synthesis later fused Mendelian genetics with Darwinian selection, and Watson and Crick's structure for DNA gave it a physical basis; extracting DNA from strawberries is a simple, tangible lab exercise.
- Physiology. Study how organisms maintain themselves: circulation, nerve impulses, hormone regulation. MIT OpenCourseWare's HST.542J, Quantitative Physiology: Organ Transport Systems, works as a course, though it is engineering-flavored and assumes calculus; OpenStax's anatomy and physiology material is a gentler alternative. Read Claude Bernard on the milieu intérieur, the internal environment an organism regulates, and then Walter Cannon, who coined the word "homeostasis" for the idea in 1926, decades after Bernard. Track your own heart rate under different conditions if you want a concrete dataset.
- Ecology. Zoom out to organisms interacting with each other and their environment: food chains, biogeochemical cycles, population and community dynamics. Charles Elton's Animal Ecology (1927) made food chains and the pyramid of numbers central to the field, and Rachel Carson's Silent Spring (1962) showed pesticides concentrating as they move up those chains. OpenStax Biology 2e's ecology chapters or Ricklefs's The Economy of Nature cover the material; for fieldwork, catalogue the species in a local park across one season.
Checkpoints
Each checkpoint is tagged with the stage of the cycle it tests.| Stage | Checkpoint | Attempts |
|---|---|---|
skepticism | Explain natural selection without teleological language such as "in order to," and state what evidence made the idea of fixed, unchanging species untenable. | Post the first attempt |
formalism | Solve Mendelian genetic crosses and run a chi-square test on Mendel's published pea counts. | Post the first attempt |
formalism | Simulate genetic drift in a small population in code and show how population size changes the time to fixation. | Post the first attempt |
abstraction | Explain homeostasis as negative feedback and map it onto a thermostat controller, linking to E.1. | Post the first attempt |
intuition | Read the last paragraph of Watson and Crick's 1953 paper and explain what copying mechanism the structure suggested, and why. | Post the first attempt |