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Unit 3: Classification. Dichotomous Key. Used to identify organisms based on the structures of that organism Organism: any living thing (plant, animal, fungi, bacteria) Structure: any physical characteristic (2 eyes, legs, feathers, tail). Dichotomous Key (cont.).
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Dichotomous Key Used to identify organisms based on the structures of that organism Organism: any living thing (plant, animal, fungi, bacteria) Structure: any physical characteristic (2 eyes, legs, feathers, tail)
Dichotomous Key (cont.) It’s easier to study things if they are grouped together Aristotle: Greek man who was one of the first people to group organisms into groups. His work is the basis for how we classify organisms today.
Traits Any physical or behavioral characteristic of an organisms - Physical: eyes, wings, mouth, color • Behavioral: nocturnal, ability to fly, mating calls Traits can be affected in one of two ways: selective breeding or natural selection
Natural Selection When organisms that are better suited to their environment, survive and pass on their traits to the next generation - giraffes with long necks survived better then giraffes with short necks - cheetahs that can run fast survived better then cheetahs that ran slower
Natural Selection(cont.) Things that increase survival • Migration (traveling to warmer/cooler weather) • Camouflage (blending in with surroundings) • Bright colors (signal poisonous creatures)
Selective Breeding When humans choose which organisms will breed in order to get an offspring with a certain characteristic • Chickens and pork bred for meat • Cows bred for either meat or milk • Horses bred for speed • Dogs bred for hunting, guard dogs, seeing eye dogs