Unformatted text preview: Teresa Audesirk Gerald Audesirk Bruce E. Byers Biology: Life on Earth
Chapter 1 An Introduction to Life on Earth What is Science? Study of Natural phenomena Natural Causality Natural events occur as a result of natural cause The Scientific Method: procedure for studying science or Problem Preliminary Information Data/Discussion The Scientific Method
Hypothesis Experiment Control possible explanation / educated guess tests hypothesis in controlled environ. standard of comparison
vs. 1 Experimental Variable correlate this w/observation Must communicate in detail OBSERVATION: Flies swarm around meat left in the open; maggots appear on meat. QUESTION: Where do maggots on meat come from? HYPOTHESIS: Flies produce maggots PREDICTION: IF keep flies away from meat, THEN will prevent
C O N T R O L Experiments of Francesco Redi EXPERIMENT: the appearance of maggots. Obtain identical pieces of meat and two identical jars Place meat in each jar. Leave jar uncovered Experimental Variable: gauze prevents entry of flies Cover jar with gauze E X P T. Leave exposed for several days Controlled Variables: clean jars, Leave covered for several days similar pieces of meat, time, temperature, place Flies swarm around and maggots Flies kept from meat; no maggots Results appear appear CONCLUSION: Spontaneous generation of maggots from meat does not occur;
flies are probably the source of maggots. Scientific Theories
Scientific Theory Explanation of natural phenomena More general & reliable than Hypothesis Survived through challenges Examples Atomic, Gravitation, Cell, Evolution Never permanent or final "truth" Characteristics of Living Things 1: Complex, organized and made of cells 2: Respond to stimuli 3: Homeostasis maintains internal conditions 4: Must get nutrients & energy 5: Growth 6: Reproduce themselves 7: Capacity to evolve Salt; Organized but simple Organized Oceans; Complex but unorganized Complex, Organize d & made of Cells Complex Water flea; Organized and complex Organized and complex Respond to Stimuli
Internal Stimuli External Stimuli Body temp, thirst, Blood sugar levels, hunger Sound, Temp, Pain Taste: avoid bitterness Plants grow toward light Homeostasis
Examples Body "staying the same"
sweat when hot shiver when cold thirst when H2O is low physical repair Maintain pH, salt, sugar, etc. levels So proteins fold normally Preventing disintegration requires energy Acquire Nutrients and Energy
Food Metabolism Nutrients Energy Heterotroph Autotroph extract nutrients and energy (ATP) by metabolism sum total of all chemical reactions needed for life atoms & molecules ability to do work Consumer; eats other organisms Who? Animals, Fungi, most Bacteria Producer; Photosynthesis 6H2O + 6CO2 C6H12O6 + 6O2 Who? Plants, Algae, some Bacteria All energy flows from sun Usable energy decreases by decomposers Reproduction
Perpetuation of parents' genetics
Stored in Chromosomes = DNA + protein Genes = segments of DNA that code for RNA Growth
Homeostasis + Increase in size/mass
Timing, Size, Shape Genetically programmed Descent of modern organisms with modifications from preexisting life forms Result of 3 Natural Processes Populations extremely variable Much variability is inherited via genes Survival is competitive Good" genes (help grow & reproduce) passed on more often = Adaptation (structure, physiology, behavior) Bad" genes passed on less often More time more change Eventually much different Inheritance Evolution Genetic Variation Natural Selection Stable Environment Changing Environment Oceans Shark = "Living Fossil" Species must adapt or go extinct Eg. Dinosaurs, Mayans Evolution Evolution: Unifying Theory of Biology Explains origin & diversity of life Extremophiles The domain Bacteria The domain Archaea (Extremophiles) A protist (domain Eukarya) The kingdom Plantae (domain Eukarya) The kingdom Fungi (domain Eukarya) The kingdom Animalia (domain Eukarya) ...
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