AP Biology Midterm

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During a study session about evolution, one of your fellow students remarks, \”The giraffe stretched its neck while reaching for higher leaves; its offspring inherited longer necks as a result.\” Which statement is most likely to be helpful in correcting this student’s misconception?
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Characteristics acquired during an organism’s life are generally not passed on through genes.
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Charles Darwin was the first person to propose what?
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A mechanism for evolution that was supported by evidence.
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In Darwin’s thinking, the more closely related two different organisms are, that what?
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more recently they shared a common ancestor
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Natural selection is based on all of the following except what?
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individuals adapt to their environments and, thereby evolve.
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Which statement about natural selection is most correct?
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Well-adapted individuals leave more offspring, and thus contribute more to the next generation’s gene pool, than do poorly adapted individuals.
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Given a population that contains genetic variation, what is the sequence of the following events, under the influence of natural selection?
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2. A change occurs in the environment. 4. Poorly adapted individuals have decreased survivorship. 1. Well-adapted individuals leave more offspring than do poorly adapted individuals. 3. Genetic frequencies withing the population change.
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During drought years on the Galapagos, small, easily eaten seeds became rare, leaving mostly large, hard-cased seeds that only birds with large beaks can eat. If a drought persists for several years, what should one expect to result form natural selection?
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More small-beaked birds dying than larger-beaked birds. The offspring produced in subsequent generations have a higher percentage of birds with large beaks.
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Which of the following must exist in a population before natural selection can act upon that population?
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Genetic variation among individuals.
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Which statement best describes the evolution of pesticide resistance in a population of insects?
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Offspring of insects that are genetically resistant to the pesticide become more abundant as the susceptible insects die off.
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DDT was once considered a \”silver bullet\” that would permanently eradicate insect pests. Today, instead, DDT is largely useless against many insects. Which of these would have been required for this pest eradication effort to be successful in the long run?
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None of the individual insects should have possessed genomes that made them resistant to DDT.
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Of the following anatomical structures, which is homologous to the wing of a bird?
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Flipper of a cetacean (dolphin)
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If two modern organisms are distantly related in an evolutionary sense, then one should expect that what?
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They should share fewer homologous structures than two more closely related organisms.
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Structures as different as human arms, bat wings, and dolphin flippers contain many of the same bones, these bones having developed from very similar embryonic tissues. How do biologists interpret these similarities?
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By identifying the bones as being homologous, and By proposing that humans, bats, and dolphins share a common ancestor.
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Logically, which of these should cast the most doubt on the relationships depicted by an evolutionary tree?
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Relationships between DNA sequences among the species did not match relationships between skeletal patterns.
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Which of the following is not an observation or inference on which natural selection is based?
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Poorly adapted individuals never produce offspring.
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Which of the following pairs of structures is least likely to represent homology?
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The wings of a bird and those of an insect
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Which of these is the smallest unit that natural selection can change?
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a population’s gene frequency
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Each of the following has a better chance of influencing gene frequencies in small populations than in large populations, but which one most consistently requires a small population as a precondition for its occurrence?
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genetic drift
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Which is a true statement concerning genetic variation?
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It must be present in a population before natural selection can act upon the population.
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Which describes an African butterfly species that exists in two strikingly different color patterns?
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disruptive selection
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Which describes brightly colored peacocks mating for frequently than drab peacocks?
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sexual selection
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Fossil evidence indicates that horses have gradually increased in size over geologic time. Which of the following terms best describes this?
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directional selection
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A certain species of land snail exists as either a cream color or a solid brown color. Intermediate individuals are relatively rare. Which of the following terms best describes this?
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disruptive selection
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Heterozygote advantage should be most closely linked to which of the following?
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stabilizing selection
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Which of the following statements about species, as defined by the biological species concept, is (are) correct? I. Biological species are defined by reproductive isolation. II. Biological species are the model used for grouping extinct forms of life. III. Tho biological species is the largest unit of population in which successful reproduction is possible.
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I and III
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Males of one species sing only when its predators are absent; males of another species sing only when its predators are present.
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behavioral
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One species lives only in tree holes; another species leaves only in streams.
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habitat
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One species mates at the season when daylight is increasing from 13 hours to 13 hours, 15 minutes; another species mates at the season when daylight is increasing from 14 to 14 hours, 15 minutes.
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temporal
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Males of one species are too small to perform amplexus (an action that stimulates ovulation) with females of all other species.
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mechanical
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Dog breeders maintain the purity of breeds by keeping dogs of different breeds apart when they are fertile. This kind of isolation is most similar to which of the following reproductive isolating mechanisms?
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habitat isolation
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Rank the following from most general to specific: 1. gametic isolation 2. reproductive isolating mechanism 3. pollen-stigma incompatibility 4. prezygotic isolating mechanism
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2, 4, 1, 3
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Two species of frogs belonging to the same genus occasionally mate, but the offspring fail to develop and hatch. What is the mechanism for keeping the two frog species separate?
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the postzygotic barrier called hybrid inviability
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The biological species concept is inadequate for grouping what?
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asexual organisms
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Which example below will most likely guarantee that two closely related species will persist only as distinct biological species?
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reproductive isolation from one another
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A rapid method of speciation that has been important in the history of flowering plants is what?
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polyploidy
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Beetle pollinators of a particular plant are attracted to its flowers’ bright orange color. The beetles not only pollinate the flowers, but they mate while inside of the flowers. A mutant version of the plant with red flowers become more common with the passage of time. A particular variant of the beetle prefers the red flowers to the orange flowers. Over time, these two beetle variants diverge from each other to such an extent that interbreeding is no longer possible. What kind of speciation has occured in this example, and what has driven it?
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sympatric speciation, habitat differentiation
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A hybrid zone is properly defined as what?
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an area where mating occurs between members of two closely related species, producing viable offspring
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The most likely explanation for the high rate of sympatric speciation that apparently existed among the cichlids of Lake Victoria in the past is what?
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sexual selection
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According to the concept of punctuated equilibrium, the \”sudden\” appearance of a new species in the fossil record means what?
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speciation occurred rapidly in geologic time
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Which gas was least abundant in Earth’s early atmosphere, prior to 2 billion years ago?
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oxygen
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Which of the following is the correct sequence of these events in the origin of life? I. formation of protobionts II. synthesis of organic monomers III. synthesis of organic polymers IV. formation of DNA-based genetic systems
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II, III, I, IV
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Which is a defining charateristic that all protobionts had in common?
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a surrounding membrane or membrane-like structure
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RNA molecules can both carry genetic information and be catalytic. This supports the proposal that what?
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RNA was the first hereditary information.
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An early consequence of the release of oxygen gas by plant and bacterial photosynthesis was to what?
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cause iron in ocean water and terrestrial rocks to rust (oxidize)
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Which free-living cells were the earliest contributors to the formation of Earth’s oxidizing atmosphere?
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cyanobacteria
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Which of the following statements provides the strongest evidence that prokaryotes evolved before eukaryotes?
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The oldest fossilized cells resemble prokaryotes.
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What is thought to be the correct sequence of these events, from earliest to most recent, in the evolution of life on Earth? 1. origin of mitochondria 2. origin of multicellular eukaryotes 3. origin of chloroplasts 4. origin of cyanobacteria 5. origin of fungal-plant symbioses
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4, 1, 3, 2, 5
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Which of these observations fails to support the endosymbiotic theory for the origin of eukaryotic cells?
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the existence of structural and molecular differences between the plasma membranes of prokaryotes and the internal membranes of mitochondria and chloroplasts
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The scientific discipline concerned with classifying organisms and determining their evolutionary relationships
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systematics
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Which of these illustrates the correct representation of the binomal scientific name for the African lion?
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Panthera leo (italicized)
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A phylogenetic tree that is \”rooted\” is one
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at whose base is located the common ancestor of all taxa depicted on that tree
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Which of the following pairs are the best examples of homologous structures?
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bat wing and human hand
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Some molecular data place the giant panda in the bear family but place the lesser panda in the raccoon family. Consequently, the morphological similarities of these two species are probably due to what?
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possession of analogous structures
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A taxon, all of whose members have the same common ancestor, is what?
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monophyletic
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When using a cladistic approach to systematics, which of the following is considered most important for classification?
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shared derived characters
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What probably explains the inclusion of rabbits in this research?
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They are the outgroup.
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outgroup
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A species or group of species that is closely related to the group of species being studied, but clearly not as closely related as any study-group members are to each other.
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Which statement represents the best explanation for the observation that the nuclear DNA of wolves and domestic dogs has a very high degree of homology?
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Dogs and wolves shared a common ancestor very recently.
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In a comparison of birds with mammals, having four appendages is what?
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a shared ancestral character
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Which of these is the most common compound in the cell walls of gram-positive bacteria?
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peptidoglycan
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Penicillin is an antibiotic that inhibits enzymes form catalyzing the synthesis of peptidoglycan, so which prokaryotes should be most vulnerable to inhibition by peptidoglycan?
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gram-positive bacteria
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gram-positive bacteria
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Bacteria that have a thick peptido glycan cell wall, and no outer membrane. They stain very darkly (purple) in Gram stain.
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gram-negative bacteria
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Bacteria that have a thin peptidoglycan cell wall covered by an outer plasma membrane. They stain very lightly (pink) in Gram stain. Gram-negative bacteria are typically more resistant to antibiotics than Gram-positive bacteria.
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In a bacterium that possesses antibiotic resistance and the potential to persist through very adverse conditions, such as freezing, drying, or high temperatures, DNA should be located within, or be part of, which structures? 1. nucleoid region 2. flagellum 3. endospore 4. fimbriae 5. plasmids
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1, 3, and 5
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Which two structures play direct roles in permitting bacteria to adhere to each other, or to other surfaces? 1. capsules 2. endospores 3. fimbriae 4. plasmids 5. flagella
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1 and 3
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Which statement about the genomes of prokaryotes is correct?
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The prokaryotic chromosome is not contained within a nucleus but, rather, is found at the nucleoid region.
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Which of the following gram-positive prokaryotic cell structure is composed almost entirely of peptidoglycan?
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cell wall
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Which of the following gram-positive prokaryotic cell structures requires ATP to function, and permits some species to respond to taxes?
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flagellum
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Not present in all bacteria, this cell covering enables cells that possess it to resist the defenses of host organisms. What is it?
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capsule
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Which of the following is a structure that permits conjugation to occur?
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sex pilus
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Which of the following is an important source of endotoxin in gram-negative species?
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sex pilus
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Which of the following contains a copy of the chromosome, along with a small amount of dehydrated cytoplasm, within a tough wall?
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endospore
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Regrading prokaryotic reproduction, which statement is correct?
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Mutation is a primary source of variation in prokaryote populations.
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If new genetic variation in the experimental populations arose solely by spontaneous mutations, then the most effective process for subsequently increasing the prevalence of the beneficial mutations in the population over the course of generations is what?
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binary fission
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An organism that obtains its energy from chemicals
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chemotroph
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A prokaryote that obtains both energy and carbon as it decomposes dead organisms
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heterotroph and chemotroph
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An organism that relies on photons to excite electrons within its membranes
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phototroph
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Which of the following traits do archaeans and bacteria share? 1. composition of the cell wall 2. presence of plasma membrane 3. lack of a nuclear envelope 4. identical rRNA sequences
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2 and 3
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Charles and Francis Darwin concluded from their experiments on phototropism by grass seedlings that the part of the seedling that detects the direction of light is the what?
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tip of the coleoptile
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Plants growing in a partially dark environment will grow toward light in a response called phototropism. Choose the incorrect statement regarding phototropism.
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Auxin causes a decrease in growth on the side of the stem exposed to light.
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A plant seedling bends toward sunlight because why?
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Auxin is found in greatest abundance on the dark side of the stem.
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The apical bud of a pine tree inhibits the growth of lateral buds through the production of what?
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auxin
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The ripening of fruit and the dropping of leaves and fruit are principally controlled by what?
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ethylene
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Which one of the following is not a direct function of either auxin or gibberellin?
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inducing semescence and ripening
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Which of the following statements about plant hormones is false?
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Abscisic acid generally promotes growth.
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The plant hormone involved in aging and ripening of fruit it what?
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ethylene
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Plant growth regulators can be characterized by all of the following except that they what?
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Function independently of other hormones
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Buds and sprouts often form on tree stumps. Which of the following hormones would you expect to stimulate their formation?
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cytokinins
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Plant hormones can have different effects at different concentrations. This explains how what?
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auxin can stimulate cell elongation in apical meristems, yet will inhibit the growth axillary buds.
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Auxins (IAA) in plants are known to affect all of the following phenomena except what?
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maintenance of dormancy
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How does indoleacetic acid affect fruit development?
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promoting rapid growth of the ovary
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Which plant hormones might be used to enhance stem elongation and fruit growth?
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auxins and gibberellins
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According to the acid growth hypothesis, how does auxin work?
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By increasing wall plasticity and allowing the affected cell walls to elongate.
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Which plant hormone(s) is (are) most closely associated with cell division?
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cytokinin
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The heavy line in figure 39.1 illustrates the relationship between auxin concentration and cell growth in stem tissues. If the same range of concentrations were applied to lateral buds, what curve would probably be produced?
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Curve I
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If you were shipping green bananas to a surpermarket thousands of miles away, which of the following chemicals would you want to eliminate from the plants’ environment?
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ethylene
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Incandescent light bulbs, which have high output of red light, are least effective in promoting what?
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phototropism
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Both red and blue light are involved in what?
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stem elongation
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Seed packets give a recommended planting depth for the enclosed seeds. The most likely reason some seeds are to be covered with only 1/4 inch of soil is what?
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The seeds require light to germinate.
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A short-day plant will flower only when what?
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nights are longer than a certain critical value
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A flash of red light followed by a flash of far-red light given during the middle of the night to a short-day plant will likely do what?
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have no effect on flowering
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Most plants close their stomata at night. What color of light would be most effective in promoting stomatal opening in the middle of the night?
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blue

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