BIO SCI 94 Study Guide - Final Guide: Dusky Seaside Sparrow, Phylogenetic Tree, Species Complex
Course CodeBIO SCI 94
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1.5 DOING BIOLOGY
-Biology is a hypothesis-driven, experimental science.
-Propose a hypothesis
-Design and perform an experiment to test the hypothesis
-Analyze your data
-Results: accept or reject hypothesis (null hypothesis)
-If necessary, propose and test a new hypothesis
-Relationship between a hypothesis and a prediction:
-A hypothesis is an explanation of how the world works.
-A prediction is an outcome you should observe if the hypothesis is correct.
-Why experiments are convincing ways to test predictions?
-Because they measure predictions from two opposing hypotheses. Both predicted actions cannot occur, so one
hypothesis will be supported while the other one will not.
25.3 HOW DOES NATURAL SELECTION WORK?
-Different definitions of “fitness” in biology and everyday English?
-Biology: the ability of an individual to produce viable, fertile offspring, relative to that ability in other individuals
in the population.
-Everyday English: a physical attribute that is acquired as a result of practice or exercise.
-Different definition of “adaptation” in biology and everyday English?
-Biology: a trait that leads to higher fitness relative to individuals without the trait.
-Everyday English: suitable requirements or conditions.
-Different definition of “selection” in biology and everyday English?
-Biology: heritable variation leads to differential reproductive success.
-Everyday English: the action or fact of carefully choosing someone or something as being the best or most
26.1 ANALYZING CHANGE IN ALLELE FREQUENCIES: THE HARDY-WEINBERG PRINCIPLE
-Five assumptions of Hardy-Weinberg Model:
-Random mating: individuals were not allowed to choose a mate.
-No natural selection: all members of parental generation survived and contributed equal numbers of gametes to
the gene pool, no matter what their genotype.
-No genetic drift: no random allele frequency changes.
-No gene flow: no new alleles were added by immigration or lost through immigration.
-Allele frequencies: p + q = 1
-Genotype frequencies: p2 + 2pq + q2 = 1
36.3 WHAT THEMES OCCUR IN THE DIVERSIFICATION OF VIRUSES?
-Darwin’s four postulates on natural selection:
-The individual organisms that make up a population vary in the traits they possess (size and shape).
-Some of the trait differences are heritable.
-In each generation, many more offspring are produced than can possibly survive.
-Individuals with certain characteristics produce more offspring than others (natural selection).
-How is it possible for viruses to evolve even thought they are not alive?
-Because most viral polymerases have high error rates and viruses lack error repair enzymes, mutation rates are
extremely high, giving them the potential to evolve rapidly.
27.1 HOW ARE SPECIES DEFINED AND IDENTIFIED?
-prezygotic: prevents individuals of different species from mating.
-temporal, habitat, behavioral, gametic barrier, mechanical isolation.
-postzygotic: offspring of matings between members of different species do not survive or reproduce.
-hybrid viability, hybrid sterility.
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-Why are there so many concepts? some cases are complicated => need more than one concept.
-Dusky Seaside Sparrow:
-Using morphospecies and biological species concepts, researchers had traditionally named six subspecies
-Habitats were threatened due to geographical isolation: no gene flow.
-Dusky Seaside Sparrow: only six individuals, all were males => breed with other subspecies.
-Crossbreed between dusky males from Atlantic Coast and females from Gulf coast.
=> Fail to preserve existing genetic diversity.
28.1 PHYLOGENETIC TREES
-Parsimony: a hypothesis of relationships that requires the smallest number of character changes is most likely to be
-Read phylogenetic trees.
29.1 WHY DO BIOLOGISTS STUDY BACTERIA AND ARCHAEA?
-Difference between a bacteria, an archaea, and a eukaryote:
-Bacteria and archaea are the most abundant organisms on Earth and are found everywhere.
-Bacteria and archaea are very small, prokaryotic cells, and most are unicellular.
-Eukaryotes have a nuclear envelope; bacteria and archaea do not.
-Bacteria have cell walls that contain peptidoglycan, and archaea have phospholipids containing isoprene subunits
in their plasma membranes. Thus, the exteriors of a bacterium and arch eon are radically different.
-Bacteria play beneficial roles in bioremediation and medicines (antibiotics) but also cause some of the most
dangerous human diseases including plague, syphilis, botulism, cholera, and tuberculosis.
-Archaea and eukaryotes also have similar machinery for processing genetic information.
30.2 HOW DO BIOLOGISTS STUDY PROTISTS?
-Major differences between eukaryotic cells and prokaryotic cells.
-Eukaryotic cells contain many organelles, including a nucleus, endomembrane system, and an extensive
-Most prokaryotic cells contain few or no organelles, and no nucleus or endomembrane system and lack a
-Origin of nucleus:
-Infoldings of plasma membrane surround the chromosomes.
-Nucleus (eukaryotic cell) arises, with infoldings forming nuclear envelope and ER.
-Origin of mitochondria: endosymbiosis
-Archaeal cell surrounds and engulfs the cyanobacterium.
-Bacterium lives within host archaeal cell.
don’t breed and don’t
reproductive isolation =
- not applicable to asexual or fossil species
- difficult to assess if populations do not
- useful when biologists
have no date on gene flow
- applicable to asexual,
sexual and fossil species
- subjective (researchers often disagree
about how much or what kinds of
morphological distinction indicate
- misidentifies polymorphic species.
- misses cryptic species.
on phylogenetic tree
- widely applicable.
- logical because different
species have different
synapomorphies only if
they are isolated from gene
flow and have evolved
- relatively few well-estimated phylogenies
are currently available.
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-Endosymbiosis: host cell supplies bacterium with protection and carbon compounds. Bacterium supplies host cell
with ATP => 2 membranes (1 from the cell and 1 from the bacterium).
-Origin of chloroplasts: secondary endosymbiosis.
-Predatory protist (with a nucleus) engulfs aerobic photosynthetic protist (with a nucleus and a chloroplasts with 2
-Nucleus from the photosynthetic protist is lost, leaving the the chloroplast by itself.
-Organelle has four membranes (2 from chloroplast, 1 from photosynthetic protist, 1 from predatory protist).
32.2 HOW DO BIOLOGIST STUDY FUNGI?
-Why fungal infections are more difficult to treat than bacterial infections?
-Like humans, fungi are composed of eukaryotic cells, so what kill them can also kill the host.
-How about non-fungal organisms that cause human disease?
-Bacteria are prokaryotic and thus have many more unique targets for antibiotics.
31.3 TRANSITION TO LAND OF PLANTS
-Preventing water loss
-Cuticle: waxy layer that prevents water loss from stems and leaves.
-Stomata: have pores that allow gas exchange in photosynthetic tissues.
- Liverworts: have pores but no guard cells.
-Providing protection from UV irradiation:
-Flavonoids: UV-absorbing compounds that protect DNA from damage.
-The importance of upright growth:
-help transporting water from tissues that are in contact with wet soil to tissues that are in contact with dry air,
against the force of gravity.
-help plants becoming rigid enough to avail falling over in response to gravity and wind.
*Tracheids and vessels:
-Tracheids have a lignin-containing secondary cell wall in addition to a cellulose-based primary cell walls; pits in
the sides and ends of the cell where the secondary cell wall is absent, where water can flow efficiently from one
tracheid to the next.
-Vessel elements: found in gnetophytes and angiosperms: ends have gaps through both cell walls.
-Producing gametes in protected structures:
-Gametangia: protect gametes from drying and from mechanical damage.
-Sperm-producing gametangium: antheridium.
-Egg-producing gametangium: archegonium.
-Land plant embryos are nourished by their parent.
-Eggs that formed inside archegonia.
-Sperm swim to the egg, fertilization occurs, then the resulting zygote stays attached to the parent.
34.1 TRANSITION TO LAND OF ANIMALS
-Worms: high surface-area-to-volume-ratio to exchanges gases across body surface.
-Avoid drying out:
-Arthropod: gills/respiratory structure inside the body.
-Insects: waxy layer on the body surface, with openings to respiratory passages that can be closed when dry.
-Insect eggs: thick membrane to keep moisture in.
-Move to moister habitats.
-Hold up their bodies under their own weight
-Great structural supports - limbs, to hold their bodies up and move.
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