Chapter 1: Exploring Life

Note: My bio notes are in an ultra-condensed format. It may be impossible to understand the strange acronyms I use here. That being said, it may serve as a good review.


Page xxxviii-1

  • Snowy owl: orange eyes, 5-ft wingsp; adapt 2 tundra (insulate, nest f/m, senses, talon)
  • Adapt 2 daylight: eyelids shield, overlap FOVs → depth, eyes no move but 270° head
  • Camouflage: brown owls w/ trees, snowy w/ winter (Harry Potter), exp on effect l8r
  • Evolution: early life → array of organisms today ⇒ led 2 snowy owl

Themes in the Study of Biology

1.1 All forms of life share common properties

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  • What is life?: bio – study of life, hard 2 def so recognize by what they do, props of life:
    • order/org, reproduce, grow/dev w/ DNA, NRG (food → chemical reactions, physical act.), regulate int env (homeostasis), resp 2 stim, evo. adapt
  • Themes: org wide field of bio – emergence, structure ⇔ function, matter/NRG exg, evo

1.2 In life’s hierarchy of organization, new properties emerge at each level

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  • Scale: biosphere (all of Earth) → ecosystem (partic area, inc physical components)
  • Community: organisms in ecosystem (e.g. animals, plants, microorganisms)
  • Population: partic species in community, **organism: **indv. Living thing (e.g. alligator)
  • Organ system: group of organs do specific function (e.g. circulatory, nervous)
  • Organ: several diff **tissues: **group of cells perform specific function
    • Cell: fundamental unit of life, organelle: membrane, specific function
  • Molecule: cluster of atoms, held by chemical bonds (e.g. DNA)
  • Emergent properties: at each level, more props arise (e.g. life @ cell), “whole > sum”

1.3 Cells are the structural and functional units of life

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  • Cell: lowest level of life, regulate int env, NRG, resp to env, build/maintain org, repro
  • All organisms composed of cells: unicell (amoebas/bacteria), sub multicell, human tril
  • Types: all w/ membrane, prokaryotic: first, sole for 1.5b yr, eukaryotic: 1.8b yr ago
  • Differences: pro simple/small (e.g. bac), eu subdivide into organelles (inc. nucleus)
  • Emergence: properties of life from interactions of structures, form complx org – system
  • Systems bio: props complex so study by analyzing interactions in systems of diff size
  • Form fit func: struct ⇔ function (e.g. scrwdrv/hammer, nerve ext), analyze struc → func
  • Everything based on cells, inc. muscle movements, photosynth, respiration

1.4 Organisms interact with their environment, exchanging matter and energy

  • Interactions: Tree get water/mine/CO2, photosynt, give O2, roots break rocks/form soil
  • Consumer: eat other oisms (moose eat grass/shoots/leaves), O2 → CO2 2 use food
  • Decomposers: decompose waste/dead, recycle complex → simple chems 4 plants
  • Recycling of chemicals: 1/2 major processss, CO2/O2/H2O/ec cycle air/soil/pl/an/de
  • Energy flow: plants convert sun → sugar/etc, thru con/dec, NRG lost as heat @ ea lvl
  • Cumulative summary: several themes – emergent properties, cells, exc; next: evolution

Evolution, the Core Theme of Biology

1.5 The unity of life is based on DNA and a common genetic code

  • genes: DNA, all cells have, units that send info prnt → offspr, group into chromosomes
    • carries info for specific trait (e.g. keratin, melanin,) ctrl cell act, some turn on/off in diff cells
  • DNA: two strands in double helix, strands made up of four nucleotides – colors/letters
  • replication: when cell divides, helix unzip, new strands assembled, inher complet DNA
  • encoding: analogus arrange alphabet, nucltides as alphabet, gene usu 100/100s ltters
  • proteins: serve as tools that carry out activities, all life use code 2 DNA → protein, cells can produce other organism proteins
    • suggests we share common ancestors
  • diversity of life: arise from diff in DNA, different genes but same “languge”
  • genome: entire set of genes, typical human: 2 sets, 3b pairs ea, scientists sequence acc recent, genomics: @ molec lvl, study sets of genes, compare across species

1.6 The diversity of life can be arranged into three domains

  • bio scale dimensions: vert – mole-biosphere, horiz – diversity of organisms
  • stats: large diversity, 1.8m species so far, 10–100m total estimated
  • taxonomy: branch that names/classifies species, (subsp)/species/genus/fam/order/class/phylum/kingd/
    • example of phylum: Chordata (vertebrates)
  • domains: historically 5 kingdoms, ongoing reeval bound of kingds, 3 higher levels: Bacteria/Archaea/Eukarya
  • Bacteria/Archaea: prokaryotes, bacteria most diverse/widespread, arc live in extreme env, usu 1 cell
  • Eukarya: all eukaryotes, protists (mult. kingds): diverse usu 1-cell organisms, current assess how 2 group
  • Plantae: kingdom in Eukarya, plants, make food w/ photosynth
  • Fungi: diverse, mostly decomposers that absorb nutrients into cells
  • animals: food by eating other orgs
  • connections: sloth use trees food/shelter, tree use sloth feces nutrients, bacteria get sunlight by living on sloth back

1.7 Evolution explains the unity and diversity of life

  • evolution: process of change of life – early → diversity (e.g. mammoth 2 elephant, split from common ancestors/separate lineage,) accounts 4 kinship & diversity
  • Charles Darwin: 1859 publish On the Origin of Species by Means of Natural Selection
  • Darwin obs: 5-yr worldwide voyage: doc plants/animals, struck by adaptations 2 env, spent 2 decades continue
  • point 1 in On the Origin: species today from ancestors, “descent w/ modification,” unity + diversity of life (e.g. birds w/ diff beaks)
  • natural selection: point 2, mechanism for evolution, idea that nat env cause favorable adapt 2 survive/reproduce, 2 observations → 2 infer
    • obs: individual variation in populations, overreproduce → compete, many fail
    • infer: ≠ reprod suc (most adapt likely to rep,) acc favorable traits over time
  • how works: varied pop → eliminate certain, others reproduce → favorable traits ↑ freq (e.g. beetles)
  • major alt of species: gradual small changes acc (e.g. one species isolated, diverge)
  • fossil record: help sci trace evo history (e.g. elephants share ancestor w/ mammoths)

The Process of Science

1.8 In studying nature, scientists make observations and form and test hypotheses

Pages 10–11

  • science: way of know/understand nat world, from curious about ourselves/world, heart is inquiry (obs, hypot, test)
    • all needed is curiosity, question est. world/look for explain
  • 2 types of reasoning: inductive (identify patterns, specific -> broad), deductive (logic, broad -> specific)
  • observations: direct/indirect (trough instruments,) most sci data is recorded obs, qualitative (e.g. snowy owl,) quantitative
    • e.g. Why do leaves change color?
  • generalizations: aft collect/analyze large num of obs, use inductive reasoning (e.g. “All organisms are made of cells”)
  • hypothesis: aft obs, proposed explain for set of obs, good hypot ⇒ predictions that can be tested, may need revise
    • format: It is hypothesized that if-then…
    • can only be “supported”/“not supported,” not right/wrong
  • deductive reasoning: use 2 cre8 tests 4 hypot (e.g. orgs made of cells, humans are orgs \(\to\) humans should made of cells)
  • example: flashlight dead ⇒ dead-battery hypot or bulb burned out hypot, lead to testable predict
  • lack of proof: can’t prove hypot, can only gather evidence 2 inc confidence (e.g. old bulb could be loose, not burnt)
  • theory: broader scope than hypot, backed by large/growing evid, (usu) no contradict (e.g. theory of evolution)
    • differs from lay def, theory is NOT an idea/guess
  • repetition: obs sometimes call for reject/revise hypot, luck + planning
  • science as social act: scientist teams (inc. students,) share info (peer review pub, seminar, communic,) build/conf on another
    • nothing if don’t share
  • Scientific Thinking Module: in ea chapter, discussions encompass areas of science

1.9 Hypotheses can be tested using controlled field studies

Page 11 – Scientific Thinking

  • camoflauge obs: obs that many ani blend w/ env, consider experiment
  • hypot: beach vs. inland mouse, biologist Hoekstra (Harvard): camo protec mice ⇒ mismatch more likely to be preyed on
  • expi: 250 plastic painted mice, control group vs. non-native, record signs of predation (llky fox, coyote, owl, heron, hawk)
  • result: mismatched higher percentage of predation attacks
  • controlled experiment: designed to compare expi w/ ctrl group, ideally test one var, ex of field study (out in nature)
  • control groups: points of compare, -: not having thing, +: what should happen, exp. group fall in between
  • vars: controlled: keep same across all groups, ind: only 1: input, dep: output
graph LR
    participants --> group1(experiment group)
    participants --> group2(experiment group)
    participants --> control(control group)

Biology and Everyday life

1.10 Evolution is connected to our everyday lives

Page 12 – Evolution Connection

  • Evolution Connection Module: in ea chapter, connect evolution 2 everyday life
  • artificial selection: humans thru select breed (e.g. crop, pets) 4 millen, biotech adv (GMO, drght/fld tol, improv growth)
  • unintentional evolution: habitat loss/climate change, 100–1000x typical extinction rate, antibiotic/pesticide resist
  • evo theo help: develop conserve strat, prompt jud use of antibio/pest, drugs by tracking disease evo/genes, med plant trace

1.11 Biology, technology, and society are connected in important ways

Page 12 – Connection

  • sci vs. tech: sci – understand nat, tech – apply 4 purpose, “discover” vs. “invent,” interdep (sci use tech, tech use sci)
  • combine: e.g. Watson/Crick discover DNA 60 ya, lead to tech of DNA manip, transform medicine/agriculture/forensics
  • many issues face society – relate 2 bio (e.g. antibio,) often revolve arnd tech
  • impact: tech improve QoL but consq (climate change,) sci help identify/fix problems but need pol/econ/culture sci literacy

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