Biology - Evolution Flashcards
what is evolution?
change of genetic makeup over time
what are fossils?
remains of an extinct ancestor
where are fossils found?
sedimentary rock
what are examples of actual remains?
teeth, bones, etc.
what is petrification?
process in which minerals replace the cells of an organism
what are imprints?
impressions left by an organism (footprint)
what are molds?
form in hollow spaces of rocks as the organism decays
what are casts?
formed by minerals deposited in molds
what are homologous structures?
similar structures and evolutionary origin
examples of homologous structures:
wing of bat, flippers of whale, forelegs of horse, arms of human
what are analogous structures?
similar functions and different origins
examples of analogous structures:
wings of a fly and wings of a bat
what is the two-layer gastrula stage similar to?
the hydra (cnidarian)
what is the three-layer gastrula stage similar to?
the flatworm
what make the human embryo similar to fish?
gill slits
all organisms must contain some DNA sequences because of…..
the similarity of the enzymes involved in processes
what are vestigial structures?
appear to be useless by had an ancestral function
examples of vestigial structures?
the appendix (in herbivores it digests cellulose); the tail in humans is the coccyx; splints on the legs of horse are the remains of the side toes; python has legs that are reduced to useless bones; whales have hind-limb bones
what purpose does migration serve?
lessens intraspecific competition
what is systematics?
field of study that constructs and studies evolutionary relationships
what is cladistics?
classify organisms based on their phylogenetic relationship
what is a clade?
members have some derived characteristic that is unique to them
what is parsimony?
least complex explanation
what is the idea behind Lamarckian evolution?
acquired traits….use or disuse of an organ was passed on to offspring
What disproved Lamarckian’s theory?
that only changes in the DNA of sex cells can be inherited
why do chance variations occur?
mutation and recombination
survival of the fittest leads to an increase of….
the favorable genes in the gene pool
what is a gene pool?
sum total of all the alleles for any given trait in the population
what is gene frequency?
the relative frequency of a particular allele
for a given gene locus, p+q=1
the frequencies of the dominant and recessive allele of the gene locus add to equal 1
when does gene frequency not change? (5 things)
large population; no mutations; mating is random; no net migration; genes are all equally successful at reproducing
what is the hardy-weinberg equation:
p2 + 2pq + 2q = 1
p2 + 2pq + 2q = 1….what does this mean?
p2 = frequency of TT ; 2pq = frequency of Tt; q2 = frequency of tt
why can’t populations represent the H-W equation in real life?
real populations have unstable gene pools and migration
5 things that deviate from H-W equation?
natural selection, mutation, assertive mating, genetic drift and gene flow
what is a deme?
small local population of interbreeding organisms of the same species
t or f: gene flow is impossible between two species.
true
what is adaptive radiation?
emergence of a number of lineages from a single ancestor
what is convergent evolution?
groups on different branches develop in similar ways in similar environments
what is divergent evolution?
any difference arising from mutations or gene combinations will be maintained in an isolated population
