This site is 100% ad supported. Please add an exception to adblock for this site.

BIO 112 Study Guide 2


undefined, object
copy deck
What does population genetics study?
It studies genetic variation in populations, trying to define microevolution
What is a species?
Interbreeding organisms that produce viable offspring
What is a population?
A group of the same species living together at the same time and same place
When studying populations, what characteristics are focused on?
Quantitative characteristics that can be measured, such as finding the frequency of alleles
What is a gene pool?
It is the total aggregate of genes in a population at any one time
What does "consider the ploidy" mean?
To take into consideration the number of chromosomes that make up an organism in a population, such as diploid or haploid
What is the Hardy-Weinberg theorem?
It defines a non-evolving population by showing a gene pool that remains constant over time
What is the equilibrium formula?
aka the Hardy-Weinberg Theorem: P (squared) +2Pq + q (squared) = 1
List the meanings of the variables in the equilibrium formula.
P is the dominant allele, q is recessive, and 1 means 100% of the population
What is an allele?
An alternate form of a gene
What are loci?
Locations of given genes with specific chromosomes
What are the five assumptions of a non-evolving population?
1) Large sample size to prevent genetic drift ("drifting" of the bell curve). 2) No migration (neither immigration nor emigration). 3) No net mutations (to prevent a massive phenotypic change by evolution). 4) No selection (neither artificial nor natural). 5)Random mating
What is microevolution?
The generation to generation change in a population's allelic frequency
What is genetic drift?
A change (evolution) in a population's allelic frequency due to chance
Why does having a large sample size prevent genetic drift?
The smaller the sample size, the greater the deviation from an ideal result
What is the bottleneck effect?
Genetic drift due to a drastic reduction in population size
What is the founder effect?
Genetic drift due to a small number of individuals colonizing an isolated area or new habitat
What is natural selection?
Differential success in the reproduction of individual phenotypes due to their interactions with environmental factors
What is artificial selection?
Selective breeding to encourage desirable traits in domesticated organisms
What is directional selection as per microevolution?
Change in allelic frequency of a population over time that favors one extreme phenotype
What is diversifying/disruptive selection as per microevolution?
Selection favoring both extreme phenotypes of a population
What is stabilizing selection as per microevolution?
Selection favoring the average phenotype of a population
What is mutation?
The random change(s) in nucleotide sequence in DNA
What is polyploidy?
More than two sets of complete chromosomes
What is balanced polymorphism?
The ability of natural selection to maintain stable frequencies of two + phenotypes
Of mechanisms maintaining variation, what is the heterozygote advantage?
Heterozygotes are favored with greater survivorship, such as malaria resistance in sickle-cell heterozygotes
Of mechanisms maintaining variety, what is the frequency dependent selection?
Survivorship declines if a morph becomes too frequent in the population
Of mechanisms maintaining variation, what is polymorphism?
Two or more distinct morphs are found and well-represented in a population
Is the following an example of frequency dependent selection or polymorphism: In a beetle population there are several black beetles and a couple of orange ones. More black beetles are randomly eaten, but the orange beetles are preferred for mating.
Both; Polymorphism is shown because there is more than one form. Frequency dependent selection is shown because the recessive orange beetles are chosen as mates and more black beetles are eaten.
Of mechanisms maintaining variation, what is geographic variation?
Variation on populations due to small or large scale geographic differences, such as the lizards in different habitats keeping to themselves
What are clines?
Graded change in some trait along a geographic axis
Of mechanisms maintaining variation, how does sex play a role?
Even without non-random mating, the processes that occur in meiosis generate genetic variation
What are limitations on selection regarding evolution, adaptations, mutations, and natural selection?
Limited by historical constraints; Mostly are compromises; Not always adaptive; Can only edit existing variations
What is macroevolution?
Concerning variations in nature, what is allometric growth?
Different growth rates through a lifetime, such as human body proportions
Concerning variations in nature, what is paedomorphosis?
Retention of juvenile characteristics in adult forms, such as salamanders
Concerning variations in nature, what is heterochrony?
Different growth rates for homologous structures in different species, such as human and chimp skulls
What is stabilizing selection as per macroevolution?
Average forms have highest fitness, such as human birth weights
What is directional selection as per macroevolution?
Extreme form of a trait is most adaptive, such as tongue length in anteaters
What is disruptive selection as per macroevolution?
Either extreme form is adaptive, such as light- and dark-shelled limpets
What is sexual selection?
Successful reproduction adds to fitness
How do historical constraints limit selection?
If an organism has not had a structure in its ancestry, it will not develop overnight, such as wings on humans
How do adaptations limit selection?
They are often compromises, such as seals getting around- they're well adapted to a watery environment but klutzy on land
How do mutations limit selection?
Not all genetic changes are adaptive
How does natural selection limit selection?
It acts to edit pre-existing genome
What are the six steps of the natural selection mechanism as per microevolution?
1) Population distribution of alleles. 2) Environmental influences come into play. 3)Certain characteristics allow survival of individuals with those characteristics. 4) Surviving individuals reproduce. 5) Favorable characteristics increase in the population. 6) Original and new populations become less and less alike.
What is punctuated equilibrium as per macroevolution?
Short time frame
What is gradualism as per macroevolution?
Long time frame, such as mollusks or horses progressing from miniature to modern sizes
What are three methods of speciation?
1) Allopatric- speciation in differing geographical location "homeland" (different due to distance). 2) Sympatric- speciation in the same geographical location "homeland" (different due to niche exploitation). 3) Autopolyploidy- Mutants cannot mate with parental phenotypes
What is a zygote?
Diploid + cell resulting from the union of two gametes
What is a pre-zygotic isolating mechanism?
Anything that maintains species integrity before conception and formation of a zygote
What is a post-zygotic isolating mechanism?
Anything that maintains species integrity after conception and formation of a zygote
What is hybrid sterility?
Hybrids fail to produce functional gametes, such as a mule
What is geographic isolation?
Geographical barrier, such as an ocean or mountain range
What is ecological (habitat) isolation?
Differing habitats in the same area, such as that used by African warblers
What is a hybrid?
The result of a cross between unlike parents
What is hybrid breakdown?
The offspring of hybrids have reduced viability, such as cotton
What is temporal isolation?
Time of reproduction acts as a barrier, such as diurnal and nocturnal critters or like eastern and western spotted skunks with different mating times
What is mechanical isolation?
Structural differences in reproductive structures that prevent successful mating, such as pollinators and flowers (coevolution) or internal fertilization of insects
What is hybrid inviability?
Hybrid zygote fails to develop
What is behavioral isolation?
Differences in behaviors that prevent successful mating, such as differing sage grouse species that either "parade" or "thump"
What is gametic isolation?
Male and female gametes fail to attract to each other, such as in some aquatic organisms that use external fertilization
What is co-evolution?
The change of two or more species in close association with each other, such as the orchid and wasp
What is convergent evolution?
The environment supports the same adaptive phenotypes, such as the streamlined fusiform shape of fish, sharks, whales, sea lions, etc
What is divergent evolution?
Environmental pressures cause two or more related species to become dissimilar, such as the Galapagos finches (also an example of adaptive radiation)
What is adaptive radiation?
Many species evolve from a common ancestor, adapting to several niches
What is artificial selection as per macroevolution?
Many breeds evolve from humans purposely selecting them
What are the types of selections?
Natural, artificial, directional, stabilizing, disruptive/diversifying, and sexual
What are the variation maintaining mechanisms?
Heterozygote advantage, frequency dependent selection, polymorphism, geographic variation, and sex
What are the limitations on selection?
Historical constraints, compromises, mutations, and natural selection
What are three variations in nature?
Allometric growth, paedomorphosis, and heterochrony
What is the theory of spontaneous generation?
Living organisms come from both living and non-living sources
Which scientist in the 1600s proved spontaneous generation to be wrong?
F. Redi showed maggots arise from pre-existing maggots
Which scientist in the 1700s proved spontaneous generation to be wrong?
L. Spallanzani showed heated, covered broth didn't produce micro-organisms
Which scientist in the 1800s proved spontaneous generation to be wrong and biogenesis to be right?
L. Pasteur used a bent flask with broth. When heated, the flask was blocked by condensation and no micro-organisms came of it. When the blockage was broken off and the broth cooled, micro-organisms were found.
What is biogenesis?
Living organisms come from other living organisms.
Which book did Charles Darwin publish in 1859?
"On the Origin of Species by Means of Natural Selection"
Which scientist stated that similar species came from common ancestors and when?
Jean Baptist Lamark in the 1800s
What mechanism did J.B. Lamark use?
That a trait was not influenced by genetics but by an organism's behavior and experiences in its lifetime
What was the flaw with J.B. Lamark's mechanism?
A lifetime is too short to pass on traits to offspring and genetics are most certainly involved
Which scientist stated species are modified by natural selection and when?
Charles Darwin in the 1800s
What mechanism did C. Darwin use?
Natural selection
List seven influences on C. Darwin.
Beagle voyage, field notes, bug collections, Galapagos finches, literature review, ability to think holistically, reading material
List two books and their authors that influenced C. Darwin.
"Principles of Geology" by Charles Lyell and "Principle of Populations" by Thomas Malthus
What is uniformitarianism?
Geological structures result from cycles of observable processes that have operated throughout time
What is the principle of population's main theme?
A population has the potential to grow exponentially but limiting factors/adverse conditions will decrease actual/potential populations (logistics)
What are the four main keys to the book "On the Origin of Species by Means of Natural Selection"?
1) Each organism has the potential to produce many offspring (Malthus' influence). 2) Only a limited number of those born survive (limiting factors). 3) Individuals that survive possess superior attributes that make them more likely to survive in that environment. 4) Those that survive reproduce.
What is descent with modification?
Newer forms appearing in the fossil record are modified descendents of earlier forms
What is homology?
Similarity in characteristics due to similar ancestry
What is fitness?
An individual's genetic contribution to the next generation
What is adaptive advantage?
A favorable trait that gives an individual fitness for a particular environment
What are the six main evidences of natural selection?
Comparative anatomy, molecular evidence, embryonic development, fossil record, vestigial structures, and patterns of species distribution
Who is associated with the fossil record and when?
Robert Hooke; 1668
Who came up with the law of superposition?
Nicolaus Steno
What is the law of superposition?
Successive strata of rock/soil are deposited by wind and water giving two criteria for dating: deepest strata is oldest and fossils found in the same strata are the same age
What is a fossil?
A trace of a long dead organism
Where are fossils typically found?
In sedimentary rock
What exactly is preserved as a fossil?
The hard material such as bones, though soft material has been found rarely
What are the two types of fossils?
Molds- the imprint of an organism, and casts- a mineralized replica of an organism
What are the two ages concering fossils?
Relative- a comparison of fossils in one strata to another, and absolute- estimate based on the amount of sediments above the fossil
Give four examples of mass extinctions found in the fossil record.
Burgess Shale (550 mya) massive loss of biodiversity, Permian (245-290 mya) reptiles, Cretaceous (65 mya) dinosaurs, and Toba (70,000 years ago) supervolcano
Who discovered ribozymes and when?
T. Cech c. 1980
How do ribozymes support evolution?
This is a "step-up" from proteins alone catalyzing
What are ribozymes?
RNA catalysts that can self-replicate
Is there any evidence to support the theory that life came from extraterrestrial origins?
Yes; Meteorites are found to contain organic compounds and water
How did the recreation of life experiment work?
A lab was set up to simulate the primitive atmosphere believed to have existed at the dawn of life. They were able to produce amino acids, ATP, and DNA from materials believed to have existed at that time.
Which scientists "recreated life"?
Miller/Urey c. 1950
Which scientist is responsible for the endosymbiosis theory?
L. Margulis c. 1960
What is the theory of endosymbiosis?
Multi-cellular organisms were created when anaerobic prokayotes were engulfed by aerobic prokaryotes for mutual symbiotic benefit, such as chloroplasts and mitochondria
How does embryonic homology give evidence for evolution? Give some examples.
Adult organisms may appear very different, but at the embryonic stage they appear very similar, such as having a notochord, dorsal hollow nerve cord, pharyngeal gill slits, and a postanal tail
Of patterns of species distribution, how does biogeography fit in to give evidence for evolution?
Recently found fossils compared with living organisms show that new organisms arise where similar forms once existed, such as the armadillo and the glyptodont
How are macromolecules used as evidence?
There are similarities in macromolecules and biochemical processes with differences proportional to ancestral split, such as the number of amino acids differing in the polypeptide chain for hemoglobin
How is the genetic code used as evidence?
It is nearly universal for all known life forms, as shown through genetic engineering that any code added to an organism will have the same effect, such as the luciferase gene
How does molecular homology give evidence for evolution?
There are similar characteristics that can only be seen at this level since distantly related ancestries don't show anatomical homology, such as plants and animals
What are conserved and vestigial structures?
Features that were useful to an ancestor but have been kept throughout evolutionary change though they are no longer functional today, such as the appendix, snake legs, and whale hind legs
What is the difference between homologous and analogous structures?
Similar features are due to shared ancestry; similar features are due to shared function
How does anatomical homology give evidence for evolution?
Descent with modification is evident in anatomical similarities of species in the same taxonomic category when analyzed via comparative anatomy
What does ecosystem ecology study?
All the biotic and abiotic components of a community, including trophic structures, energy flow, biogeochemical cycles, human impacts, and conservation biology
What influences the vegeation in biomes?
Temperature and precipitation
What are CHNOPS, and what percentage of them make up organisms?
Carbon, hydrogen, nitrogen, oxygen, phosphorus, and sulfur; 99.9%
What is a trophic structure?
The food chain of who eats what
Where do autotrophic organisms fit in the trophic structure, and what are they called?
In the first tier; Primary producers
Where do heterotrophic organisms fit in the trophic structure?
In the second tier and up; Primary, secondary, tertiary, quaternary, etc consumers
What eats all in the trophic structure?
What is related to the trophic structure?
Energy flow
What is ecological efficiency?
The percentage of energy transferred from one tropic level to the next, which is usually less than 20%
What is the 10% Law of Energy?
If 10% of energy is transferred from primary producers to primary consumers, and 10% of that energy is transferred to secondary consumers, then only 1% of net primary production is available to secondary consumers (10% of 10%)
What is the pyramid of biomass?
A pyramid in which each tier represents the standing crop (in dry weight) of a trophic level
What is the purpose of the pyramid of biomass?
To show important ecological consequences of low efficiencies in the trophic levels
What is the pyramid of numbers?
A pyramid in which each block represents the number of individual organisms at each of the trophic levels
What is the purpose of the pyramid of numbers?
To show that the limited biomass at the top of an ecological pyramid is concentrated in a relatively small number of large organisms
What is biological magnificiation?
Increasing levels of toxins at higher trophic levels
What are biogeochemical cycles?
Cycling of nonliving components of an ecosystem
Give an example of a biogeochemical cycle.
An example is the cycling of CHNOPS in the community and environment
List three natural sources of carbon in a slow cycle.
Atmosphere (0.03% carbon dioxide), shells (calcium carbonate), and fossils
List a natural source of carbon in a fast cycle form and its equation.
It enters the biotic cycle via photosynthesis and returns to the atmosphere via aerobic respiration; COâ‚‚+ Hâ‚‚O = C(6)H(12)O(6) + Oâ‚‚
What are sources of excess carbon?
Burning of fossil fuels (autos, industry, residential) and deforestation
What is the increase of carbon in parts per million? What is the projected by 2035?
From 315 ppm to 340 ppm; 600 ppm
What is an impact of excess carbon?
Greenhouse effect
Under normal circumstances, what does the ozone layer do?
It warms the environment, like a greenhouse
Under abnormal circumstances, what are the two scenarios concerning the ozone?
Traps heat causing global warming leading to desertification, ice melts, flooding, northern migrations, and altered weather patterns; Sinks heat causing global cooling leading to glaciations and southern migrations
What is another carbon issue causing concern?
Man-made chlorofluorocarbons (CFCs) O(3) + Cl = O + O(3)
What are the sources of CFCs?
Aerosols, industrial, and refrigerants
What is the impact of CFCs?
It reacts with the ozone layer for 30 years, causing its destruction
Why should humans care if there's a hole in the ozone layer?
It blocks ultra violet radiation so a hole in it will increase UV exposure leading to skin cancer
List a natural source of nitrogen in a fast cycle form.
Atmosphere (79% Nâ‚‚gas- not usable by most organisms)
What is nitrogen fixation?
This is the process of converting atmospheric nitrogen (Nâ‚‚) to nitrites (NOâ‚‚-) via monerans
Which specific monerans fix the nitrogen?
Soil bacteria and symbiotic bacteria
What is the formula of nitrogen fixation?
N₂+ 3 H₂= 2 NH₃
Judging from the formula, what is the direct product of nitrogen fixation?
What is nitrification?
This process converts ammonia compounds to nitrite (NO₂-) and then to nitrate (NO₃-)
What factors cause nitrification?
Aerobic bacteria in the soil and lightening
How does denitrification relate to nitrogen cycling?
This process converts nitrate (NO₃-) to nitrogen gas (N₂)
What are natural sources of phosphorus?
Guano and bedrock
How does phosphorus cycle? Is it fast or slow?
It enters biotic systems easily via autotrophs (which use it) and re-enters abiotic cycles through decay; Very slow cycling process
What are excess sources of sulfur?
Industrial exhaust and detergents
How does excess nitrogen and phosphorus enter the cycle?
Detergents and fertilizers
What are the impacts of excess nitrogen/phosphorus?
Eutrophicaton leading to algal blooms, excess growth/decay, oxygen depletion, dead lakes/ponds, and nutrient loss
What fraction of earth's surface does water cover? What percentage of the oceans provides available water?
3/4; 97%
How does water cycle?
Hydrologic cycle of differential evaporation and precipitation
What are causes of contamination?
Dams, thermal pollution, detergents, fertilizers, insectides, trash, and topsoil
What are natural sources of sulfur?
Volcanic gases
What is the impact of excessive sulfur?
Added to the hydrologic cycle, it creates acid rain leading to loss of biodiversity, severe decline in amphibians, and loss of sculpture (like ancient temples, marble statues of the Greeks, and Egyptian monuments)
What is sulfuric acid?
Hâ‚‚SOâ‚„; It has a pH of 2.9, as damaging as hydrochloric acid
List four more factors besides the mentioned that are destructive and their impacts.
Trash, deforestation, nuclear waste, and human population growth leading to topsoil reduction, desertification, habitat destruction, and decline of biodiversity
What is conservation biology?
The branch of science concerned with counteracting the biodiversity crisis

Deck Info