Bio Exam 3 Study Guide

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Bio Exam 3 Study Guide

A Flash Card Set For My Third Exam In My College Biology 101 Class

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    • Fossils in the deepest layers of rock are usually the
most primitive in a particular lineage.
  • Darwin’s visit to the Galapagos Islands was the ‘laboratory model’ of his concept of
  • Darwin’s view was that natural selection acts on the
variations found in populations.
  • Adaptations are
any traits that make individuals more successful in a particular environment.
  • Unique traits, like the hemoglobin of llamas and camels may show relationship, not
unique adaptation to harsh, but different environments.
Populations evolve; individuals...
do not.
  • Mutation produces alleles as
new genetic variation.
  • Variation can be introduced into populations by
migrants, crossing over, and sexual reproduction.
  • Neutral mutations ____ ____ ____ ____ an organism.
neither harm nor help
  • Directional selection causes one extreme phenotype
to have greater success.
  • Stabilizing selection causes extreme phenotypes
to be at a disadvantage.
  • Stabilizing selection produces what in the reproduction of humans and some bird species?
an optimum, average birthweight in humans of about 7 pounds and a modal clutch size in some bird species of  6 eggs.
  • In a stable, unchanging environment, selection may be
absent or undetectable.
  • Disruptive or diversifying selection favors
extreme phenotypes.
  • When males compete for mating opportunities, sexual selection often produces
males that are twice as large as females.
  • The HbS allele is more frequent in African populations than in the U.S. because
heterozygotes (HbA/HbS) have a reproductive advantage in an environment including malaria.
  • The ‘founder effect’ is produced by
introducing a small group onto an island.
  • The ‘bottleneck effect’ occurs when
an epidemic drastically reduces the breeding population.
  •  ‘Genetic drift’ of allele frequencies is more likely when
population numbers shrink.
  • _____ are random, heritable, and potentially useful, but unpredictable by location.
  • Natural selection does not always favor the big and strong;
adaptations must match the environmental requirements.
  • Artificial selection is a strictly _____ endeavor.
  • The fossil record is incomplete for many reasons;
fossilization was/is a rare event.
  • Fossils could include
tracks, burrows, teeth, skeletons, or casts.
  • Radioisotope dating of fossils uses
the ratio of isotope to daughter product in volcanic rocks.
  • Major changes and trends within and between lineages are described by
  • Life on earth probably originated prior to ___ BYA during the _____ eon.
3.5 BYA during the Archean eon.
  • Convergence to a similar body shape by sharks and penguins is caused by
similar selection.
  • Wings of bird and butterfly are analogous, not homologous, and show
convergence of form.
  • Earlier life forms, such as fossil reptiles, would have ____ primitive limbs than living vertebrates.
  • Genes for embryonic development are ‘conservative’ (change little) because
they act early.
  • Phylogenetic relatedness would not be indicated by mere
similarities of ecology.
  • Neutral mutations occur at a constant rate and their accumulation is useful as a
‘molecular clock.’
  • Natural selection may never act on mutations which
are neutral.
 The different ‘kinds’ of organisms are also known as different
  • The common quality of all separate species is their ______ ______ from other such kinds.
‘reproductive isolation’
  • Members of the same species can, at least potentially, mate and produce
fertile progeny.
  • The result of the process of speciation is
complete reproductive isolation.
  • Migration or ‘gene flow’ would not promote
evolutionary change.
species which use external fertilization are less likely to develop
reproductive isolation.
  • Stable gene frequencies (genetic equilibrium) is not an
‘isolating mechanism.’
  • Genetic divergence by drift or barriers and accumulated mutations can lead to
  • Isolating mechanisms happening before fertilization are
  • If the hybrid is inviable, the mechanism is a
‘postzygotic’ or acting after the zygote has formed.
  • The usual mode of ‘allopatric speciation’ requires
physical separation or geographic isolation.
  • Plants may undergo ‘sympatric speciation’ by forming
‘polyploids’ in a population.
  • Divergence from common ancestors (phylogeny) is usually represented by a
‘phylogenetic tree.’
  • Phylogeny also refers specifically to the _____ _____ among individuals.
‘evolutionary relationships’
  • Evolutionary innovations are acquired during rapid divergences called
‘adaptive radiations.’