Test #2 Flashcards
what components are required for scientific graphs?
Descriptive title, Axes titles & units, scaled numbers or labels on both axes, determine what type of graph you should construct, and graphs should be neat.
How do you construct appropriate scales for graphs?
Both axes begin at the origin (0,0), Each square on a given axis must represent the same amount, Calculate the difference between the smallest and largest values of the variable and divide the difference by the number of data points, Round up to the nearest convenient value (interval), and end the scale above the highest value.
How does the changing of the axes of a graph influence how data can be interpreted?
if the intervals on a graph are too far apart or too close together, there will be too much of a change or no change at all, making results seem like less or more than they really are.
What actions do scientists take to identify patterns in data?
Identify the independent and dependent variables, Identify if there is a key, Look where there a greater value (like a higher quantitative number) or where is there a lower value (like a lower quantitative value), identify changes, differences, or trends in the figure, and interpret by asking and answering, “What is the story this graph is telling?”
What examples of patterns did biologists see when investigating sexual selection trends?
Biologists saw that certain traits give males more reproductive success during mating, or they have intersexual relations.
Describe the nebular theory for the formation of our solar system
suggests that 4.6 billion years ago our solar system formed from the gravitational collapse of a giant interstellar gas cloud
What are the two general hypotheses about the way life-supporting molecules?
Miller-Urey and the Meteorite
Miller-Urey experiment
Miller and Urey built a model to show that organic compounds could be made by heating and passing electrical current, to stimulate lightning, through a mixture of gasses.
Meteorite analysis
Amino acids could have arrived on earth through meteorite or asteroid impact.
The two hypotheses for the formation of cell membranes
Iron-sulfide and lipid membrane
Iron-sulfide hypotheses
biological molecules combined in the compartments of chimneys made of warm sodium sulfide into a cool iron-rich solution on the ocean floor. The compartments acted as the first cell membranes.
Lipid membrane
lipid membranes spontaneously gave rise to liposomes giving rise to the first cells.
What evidence led scientists to propose that RNA, rather than DNA, was the first genetic material on early Earth?
Because RNA is a simpler form of DNA that does not need enzymes to replicate itself. It instead uses ribozymes to replicate.
What are the characteristics of life that we learned about in Unit 1?
orderly structure, reproduction, growth and development, metabolism, homeostasis, response to environment, and evolutionary adaptation.
How do the characteristics of life we learned in Unit 1 relate to Unit 2 and what we learned about early life on earth?
cells = lipid membrane hypotheses, reproduction implies that we need genetics to be passed on (DNA & RNA), and evolutionary adaptation
What are the domains of life? Which domains are single-celled and which contain multicellular organisms?
Archaea, Bacteria, and Eukarya. Eukarya is multicellular.
What organisms were the first photosynthetic organisms that added oxygen to the atmosphere?
cyanobacteria
What provides evidence that prokaryotes existed before eukaryotic organisms?
eukaryotes have both a nucleus, membrane bound organelles, and are multicellular, making them too complex to come before prokaryotes.
Describe the endosymbiont theory
suggests that mitochondria and chloroplasts were once simple prokaryotic cells that were engulfed by larger prokaryotes.
endosymbiosis
a relationship in which one organism lives within the body of another-with both organisms benefiting
Describe the autogenous theory
eukaryotic organelles evolved from infoldings of the plasma membrane, creating pockets that eventually pinched off.
Describe how the evolution of sexual reproduction led to increased diversity and variation
sexual reproduction allowed new combinations of genes to come together, increasing genetic variation
variation
the difference in the physical traits of an individual from those of other individuals in the group to which it belongs
Explain how there is evidence for evolution in the fossil record
the layers of rock fossils were found in proved rock layers each held their own types of fossils, also supporting the concept of decent with modification
evolution
the process of biological change by which descendants come to differ from their ancestors
Explain how there is evidence for evolution in biogeography
island species most closely resemble species on the nearest mainland
biogeography
migration between island and mainland species
Developmental homologous structures
similar features in the embryos of different organisms result from common ancestry.
Anatomical homologous structures
similarities in physical structures in the bodies of organisms imply common ancestry
Molecular homologies
similarities in DNA and cellular structures imply a common ancestor
Analogous structures are not evidence for evolution. Why not?
They are not evidence for evolution because they did not derive from the same original structure.
analogous structures
structures that perform a similar function but are not similar in origin
vestigial structures
remnants of organs or structures found in an early ancestor that no longer serve a useful function or may now serve a different function.
what information do vestigial structures provide for how evolution works?
They provide evidence of common ancestry between organisms that have the same structures, even if they are no longer in use/functional.
Fitness
a measure of the ability to survive and produce more offspring relative to other members of the population in a given environment
Heritability
the ability of a trait to be passed down from one generation to the next
population
all the individuals of a species that live in an area
gene pool
the combined alleles of all the individuals in a population
What observations contributed to Darwin’s proposed mechanism for natural selection?
Fossil observations, Variations among populations, Some variations appeared more helpful than others, and adaptations allow a species to better survive and reproduce in its environment, and variation in domesticated plants and animals pointed to artificial selection as a process where humans are selecting for traits
variation (natural selection)
heritable differences that exist in every population (the basis for natural selection)
overproduction (natural selection)
producing too many offspring, so only the fittest survive
adaptation (natural selection)
certain variations can cause certain individuals to survive better than others in its environment, especially if there is a quick change
Descent with modification (natural selection)
overtime, natural selection will produce species with adaptations that are well suited for survival and reproduction, meaning eventually the population will all share this beneficial trait.
It’s not survival of the fittest. It’s survival of the ____ _________. Explain what this means, giving an example
fit enough; the best option that survived in a population. EX: Ben in the giraffe video.
Natural selection may not produce a “perfectly-engineered” trait. Why not?
lack of necessary genetic variation, constraints due to natural history, and Trade offs.
directional selection
directional selection favors phenotypes at one extreme, causing rare phenotypes to become more common (graph is the same, but more towards one end usually).
Stabilizing selection
Stabilizing selection favors the “mean” phenotype and rids of variation (graph is more pushed into the average, looking taller).
Diversifying selection
Diversifying selection favors both extreme phenotypes, increasing variation (graph looks like an m, with a dip in the intermediate center).
How is antibiotic resistance inside Addie an example of natural selection?
Addie has directional selection, because the resistant bacteria inside her will become more common, making the extreme become the mean.
natural selection
the process by which individuals that are better adapted to their environment survive and reproduce more successfully than less-well-adapted individuals do. This causes these adaptations to become more frequent in the gene pool of a population. The environment is what is applying selective pressure.
Intrasexual selection
competition between males for the female
Intersexual selection
specific traits that attract/lure the females
Explain gene flow and give a specific example
the movement of alleles from one population to another. Animals moving between populations due to interbreeding
Explain genetic drift and give a specific example
The random change in allele frequency in a population (like a natural disaster happening).
bottleneck effect
genetic drift that occurs after an event greatly reduces the size of a population
founder’s effect
genetic drift that occurs after a small number of individuals colonize a new area
What are variations in traits?
referring to the variety of phenotypes we can see in a population
Key idea of the giraffe videos
genetic variation is what allows the mechanisms of evolution to work.
What are sources for genetic variation?
Sexual recombination (which provides new gene combinations) and mutations (which provide new genes through changes in DNA) are the sources of variation.
Do individuals adapt to their environment, or do populations adapt to their environment? How do you know?
Only populations evolve and adapt over time and generations. Individuals do not evolve or adapt because they cannot change the DNA that they inherited.
species
a group of organisms that are closely related and can mate to reproduce fertile offspring
speciation
the rise of two or more species from one existing species
Describe how reproductive isolation leads to speciation
when reproductive isolation happens, that means a species is no longer considered a species, creating speciation. It is the final step of speciation.
Behavioral isolation
isolation caused by differences in courtship or mating behaviors (bird dances, chemical scents, etc.)
Geographic isolation
involves physical barriers that divide a population into two or more groups (rivers, mountains, etc).
Temporal isolation
exists when timing prevents reproduction between populations (reproductive periods only happening during a certain time of year or day).
What is a phylogenetic tree and/or cladogram and how is it used?
They show the hypothesized evolutionary relationships between taxa
How are cladograms constructed?
Cladogram made by lowest scoring taxon first, and highest scoring trait first.
Carolus Linnaeus
creator of the Linnaean classification system that classified organisms based on similarities.
Georges-Louis Leclerc de Buffon
proposed that species shared ancestors instead of arising separately
Erasmus Darwin
proposed that all living things were descended from a common ancestor and that more complex life forms arose from less complex life forms.
Jean-Baptiste Lamarck
proposed that all organisms evolved toward perfection and complexity.
Charles Lyell
extended the theory of gradualism to uniformitarianism
Charles Darwin
proposed a theory of how evolution works that we still mostly use today
Compare and contrast the ideas of Lamarck and Darwin
Lamarck believed that if an organism changes in its lifetime to better fit its environment, that change is passed to its offspring. He said change is motivated by what organisms need or want, and things we dont need will eventually go away. Darwin believed that the desires of animals have nothing to do with how they evolve and adapt, and the genetically benefited animals will give their good genes to their offspring.
Artificial selection
the practice of breeding animals or plants that have certain desired characteristics/traits. In this case, the allele frequency within the gene pool of a population changes over time, but not necessarily increasing fitness, so there is not adaption happening. Humans are what is applying selective pressure.
Sexual selection
a form of natural selection that also causes certain traits to increase or decrease in frequency in the gene pool of a population, but in this case, individuals in the population are applying the selective pressure based on their preferences. The traits that increase in frequency are those that increase the ability of individuals to attract or acquire mates.
Cuvier
created the theory for extinction called catastrophism that uses fossils as evidence
Grant, Peter & Rosemary
observed natural selection in action in a population of finches, confirming the ideas of Charles Darwin
Hutton
proposed the principle of gradualism
Wallace
came up with ideas similar to Darwin based on observations of tropical organisms and geology
