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18 Cards in this Set

  • Front
  • Back
biodiversity
variety and variability among all genes, species, and ecosystems - on the planet
phase 1: the formation of small molecules containing carbon and hydrogen
under conditions similar to those on early earth, small organic molecules form, and these molecules have some chemical properties of life
phase 2: the formation of self-replicating information-containing molecules
earliest life on earth, which resembled bacteria, appeared about 3.5 billion years ago, not long after the earth was formed; no one is certain how life arose, but evidence supports the idea that self-replicating molecules - possibly RNAs - may have formed in earth's early environment
RNA world hypothesis
proposes that the world may have been filled with RNA-based life before it became filled with the DNA based life we see today
phase 3: the development of a membrane, enabling metabolism and creating the first cells
self-replicating molecules later acquired or developed membranes, enabling them to replicate and making metabolism possible, the 2 conditions that define life
microspheres
compartmentalization of self-replicating information containing molecules into microspheres may have been an important stage as the first living cells arose
species
biologists use this world to label different kinds of organisms
biological species concept
species are populations of organisms that interbreed or could possibly interbreed with each other under natural conditions and that cannot interbreed with organisms outside their own group
reproductive isolation
the inability of individuals from 2 populations to produce fertile offspring with each other - making it impossible for gene exchnage between the populations to occur
prezygotic barriers
make it impossible for individuals to mate with other or if they can mate, make it impossible for the male's reproductive cell to fertilize the female's reproductive cell
postzygotic barriers
occur after fertilization and generally prevent the production of fertile offspring from individuals of 2 different species - called hybrids
organization of life
-domain (bacteria, archaea, eukarya)
-kingdom (protists, plants, fungi, animals)
-phylum: giraffe (chordata)
-class (mammalia)
-order (artiodactyla)
-family (giraffidae)
-genus (giraffa)
-species (giraffa camelopardalis)
postzygotic barriers
occur after fertilization and generally prevent the production of fertile offspring from individuals of 2 different species - called hybrids
organization of life
-domain (bacteria, archaea, eukarya)
-kingdom (protists, plants, fungi, animals)
-phylum: giraffe (chordata)
-class (mammalia)
-order (artiodactyla)
-family (giraffidae)
-genus (giraffa)
-species (giraffa camelopardalis)
the biological species concept doesn't always work
1-classifying asexual species: asexual reproduction does not involve interbreeding so the concept of reproductive isolation is no longer meaningful
2- classifying fossil species: differences in size and shape of fossil bones cannot reveal whether there was reproductive isolation between the individuals from whom the bones came
3- determining when one species has changed into another: there is rearely a definitive moment making the transition from 1 species to another
biological species concept #2
4- classifying ring species: 2 non-interbreeding populations may be connected to each other by gene flow through another population so there is no exact point where 1 species stops and the other begins
5- classifying hybridzing species: hybridization- the interbreeding of closely related species - sometimes occurs and prouduces fertile offspring, suggesting that the borders between the species are not clear cut
speciation
in which 1 species splits into 2 distinct species, occurs in 2 phases and requires more than just evolutionary change in a population
microbes
the most abundant organisms on earth- don't have skeletal, respiratory, circulatory, digestive or nervous systems because they are too small to need them