chapter 1: biology and the tree of life Flashcards
organsim
a life-form made up of 1+ cells
cells
membrane-bound units that make up organisms
genes
units of hereditary information
five fundamental characterisitcs of life
- cells
- replication
- evolution
- information
- energy
theory
an explanation for a general class of phenomena or observations that are supported by a wide body of evidence (not a speculation or guess)
Robert Hooke
Englishman who discovered compartments (“cells”) in cork by using a microscrope in 1665
Anton van Leeuwenhoek
Dutch scientist who developed more powerful microscopes and discovered single-celled organisms in pond water (“animalcules”)
Rudolf Virchow
German scientist who proposed that all cells arise from cells already in existence (“all-cells-from-cells hypothesis”)
cell theory
all organisms are made of cells, and all cells come from preexisting cells
hypothesis
a testable statement explaining a phenomenon or a set of observations (hypotheses = tightly focused questions; theories = proposed explanations for broad patterns)
Louis Pasteur
French scientist whose experiment (involving two flasks, a straight-necked flask with broth exposed to cells in the air and a swan-necked flask that prevented the broth from coming in contact with cells) provided conclusive evidence for the all-cells-from-cells hypothesis over the spontaneous generation hypothesis
experiment
a test of the effect of a single, well-defined factor on a particular phenomenon
experimental prediction
a measurable or observable result that must be correct if a hypothesis is valid
chemical evolution
the process through which life arose from non-life early in Earth’s history
species
distinct, identifiable types of organisms
Charles Darwin and Alfred Russel Wallace
English scientists who indepedently developed the theory of evolution and proposed the idea of natural selection
evolution
a change in the characteristics of a population over time; occurs when heritable variation leads to differential success in reproduction
population
a group of individuals of the same species living in the same area at the same time
natural selection
the proccess (acting on individuals) by which evolution occurs; when heritable traits leads to increased reproductive success, those traits become more common in the population over time. this explains why species change over time and why they are so well-adapted to their habitats.
heritable characteristics
traits that can be passed on to offspring
speciation
process by which natural selections causes a population of one species to diverge and form a new species
fitness
an individual’s ability to produce surviving offspring