General Biology: Evolution, Ecology, Biogeocenology, Biosphere
What you must understand
Evolution: Lamarck explained change by use and inheritance of acquired traits; Darwin proposed natural selection acting on heritable variation. Modern synthesis adds populations, mutations, genetic drift, isolation and gene flow. Evidence: fossil record, comparative anatomy (homologous and analogous organs, rudiments, atavisms), embryology, molecular data. Speciation requires reproductive isolation; the driving forces are mutation, recombination, selection, drift, and isolation. Direction: aromorphosis (major advance), idioadaptation (particular adaptation), degeneration.
Ecology: an ecosystem has biotic components (producers, consumers, decomposers) and abiotic factors; energy flows one way while matter cycles. A food chain transfers roughly a tenth of energy to the next level, so pyramids taper. A population is described by size, density, age structure and growth.
Biogeocenosis is a self-regulating community plus its environment; biosphere is the global living shell, with the living matter redistributing elements. Human impact includes pollution, habitat loss, and conservation measures such as protected areas.
Traps
- Homologous organs share origin, analogous organs share function only.
- Energy does not cycle; matter does.
- Decomposers are not consumers, though both are heterotrophs.
- Aromorphosis is a major change opening new habitats; idioadaptation is a fine adjustment.
Rule of thumb
For any ecological question, place the organism in a trophic level, then trace energy direction and matter cycling.
Worked example: Grass (producer) → rabbit (primary consumer) → fox (secondary consumer). If grass stores 10 000 units of energy, roughly 1 000 reach rabbits and 100 reach foxes.