Test 1 F21 Flashcards

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Which of the following statements is most consistent with the model of evolutionary relatedness represented in the phylogenetic tree?

Salamanders are a sister group to the group containing lizards, goats, and humans.

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In the phylogenetic trees shown, each number represents a unique species of organisms. Which two species are represented as sister species in Tree 2 but are not represented as sister species in Tree 1?

3 and 4


Which of the following pairs is the best example of homologous structures?

bones in the bat wing and bones in the human forelimb


To apply parsimony to constructing a phylogenetic tree,

choose the tree that represents the fewest evolutionary changes, in either DNADNA sequences or morphology.

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In the figure, the letters A-G represent individual species that all descended from a common ancestor. Which of the following groups of these species forms a monophyletic group?

E, F, and G


Why do researchers use rRNA in investigations of relationships between taxa that diverged hundreds of millions of years ago?

DNA coding for rRNA changes relatively slowly.


The evolution of vascular tissue in plants facilitated which of the following changes?

the ability to grow taller


Which of the following factors most likely helped early plants colonize land?

formation of mutualistic associations with fungi


Which of the following structures is a modified horizontal shoot growing along the soil surface?



Part completeOnions are monocots with certain parts adapted for storage. From which of the following plant parts is the main storage structure formed?

leaf sheaths


Suppose a flower had normal expression of genes AA and CC and expression of gene BB in all four whorls. Based on the ABCABC hypothesis, what would be the structure of that flower, starting at the outermost whorl?



After a drought in 1977, researchers hypothesized that on the Galapagos Island Daphne Major, medium ground finches with large, deep beaks survived better than those with smaller beaks because they could more easily crack and eat the tough Tribulus cistoides fruits. A tourist company sets up reliable feeding stations with a variety of bird seeds (different types and sizes) so that tourists can get a better look at the finches. Which of the following events is now most likely to occur to finch beaks on this island?

increased variation in beak size and shape over time


Which of the following statements best describes evolution?

Populations change genetically from one generation to the next.


Layers of sedimentary rock found on top of other layers of sedimentary rock can be assumed to be...

younger than underlying layers


Darwin argued that a few key observations provided evidence for his mechanism of evolution by natural selection. In which of these scenarios would adaptations fail to develop via natural selection, given Darwin's observations?

A population of squirrels varies in coat color due to exposure to sunlight. Squirrels with brighter coats live just as long and have just as many offspring as those with darker coats.


Lizards on small Caribbean islands can survive strong storm surges from periodic hurricanes. Direct observations of these populations help support the theory of evolution by natural selection because...

lizards that have heritable behaviors to cling to branches are more likely to survive storm surges, and surviving generations immediately after hurricanes demonstrate remarkable clinging behavior and associated phenotypes (such as stronger limbs) compared to pre-hurricane lizards


A good example of convergent evolution would be...

snakes and small mammals both evolving integumentary membranes that allow them to glide from tree to tree to more efficiently forage for food

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Use the diagram to answer the next question.

Which of the following conclusions is most consistent with the information in the evolutionary tree shown above?

Crocodiles are more closely related to hawks than to lizards.


Lamarck proposed that species could evolve through the use and/or disuse of their anatomy, such that giraffes that stretch their necks more can have offspring with longer necks. What is wrong with this argument?

A giraffe stretching its neck within its own lifetime is not necessarily a heritable trait


The theory of evolution through natural selection is considered a scientific theory because __________.

All of the listed answers are correct.


How does homology provide evidence for evolution?

homologous structures are similar in development and underlying anatomy between different species that may even utilize those structures for different purposes, suggesting that the shared similarities result from common ancestry


Which of the following is true of microevolution?

it is the kind of evolution that can change the relative abundance of a particular allele in a gene pool over the course of generations


Two juniper trees (Juniperus scopulorum and J. monosperma) have overlapping geographic ranges. Pollen grains (which contain sperm cells) from one species are unable to germinate and make pollen tubes on female ovules (which contain egg cells) of the other species. Which of the following isolating mechanisms keeps the two species separate?

gametic isolation


A population of dark-eyed junco birds became established near the California coastline, many miles from the junco's normal habitat in the mixed-coniferous temperate forests in the mountains. Juncos have white outer tail feathers that the males display during aggressive interactions and during courtship displays. Males with more white in their tail are more likely to win aggressive interactions, and females prefer to mate with males with more white in their tails.

Population sizes in the coastal areas have been reasonably large, and there are significant differences between the coastal and the mountain habitats. The coastal habitat is more open (making birds more visible) and has a lower junco density (decreasing intraspecific competition) than the mountain forests. Given this information, which of the following evolutionary mechanisms is the most likely cause of the difference between the coastal and mountain populations?

natural selection


Which answer appropriately describes an example of stabilizing selection?

Mutational variation in the gene sequence for an important developmental gene that regulates the number of vertebrae in the neck of mammals is not tolerated, with essentially all mutant alleles selected against each generation compared to the predominate allele in the population


Which of the following characteristics is a postzygotic barrier that prevents hybrids between two species from producing offspring?

hybrid breakdownincreased hybrid fertilityhybrid gamete isolationincreased hybrid vulnerability


Which of the following processes best describes the cause of a bottleneck effect?

drastic decrease in the size of the population


A limitation to the biological species concept would be it's failure to apply to

all of these answers are correct


Which of the following correctly pairs pre- or post-zygotic isolating mechanisms with a specific reproductive barrier?

pre-zygotic; behavioral isolation


In the ecological species concept, two populations are considered different species if...

they have distinct ecological roles such that hybrids, while possible, tend not to be as competitive at either ecological niche


Allopatric speciation occurs due to __________ between previously reproductively compatible populations

a physical barrier


Mutations in the DNA related to the development of Alzheimer's Disease in human are estimated to be at Hardy Weinberg Equilibrium in the human population. This most likely suggests that...

the development of Alzheimer's disease at an old age has little impact on reproductive success, which occurs prior to disease development


Which population is most likely to be in Hardy Weinberg Equilibrium?

very large population, external fertilization from spawn broadcasting (gametes randomly meetup in the water column), very isolated from related populations in a deep sea canyon


Males of different species of the fruit fly Drosophila that live in the same parts of the Hawaiian Islands have different elaborate courtship rituals. These rituals involve fighting other males and making stylized movements that attract females. Which type of reproductive isolation maintains these species as separate despite living in sympatry?

behavioral isolation


Which of the following statements is the best definition of a hybrid zone?

an area where mating occurs between members of two closely related species, producing viable offspring


If one organ is an exaptation of another organ, then which of the following statements is most accurate?

The two organs are homologous.


A species of centipede, which normally has dozens of nearly identical body segments with similar appendages adapted into walking legs and a head region in which the appendages form antennae, evolved a series of mutations in its Hox genes, leading to homeotic changes in the phenotype. Which of the following types of phenotypic alterations would be consistent with homeotic evolution?

The posterior most segments that usually have walking legs now have large antennae instead.


Fossilized stromatolites

resemble structures formed by bacterial communities that are found today in some shallow marine bays.


The oxygen revolution changed Earth's environment dramatically. Which of the following took advantage of the presence of free oxygen in the oceans and atmosphere?

the evolution of cellular respiration, which used oxygen to help harvest energy from organic molecules


Why do some scientists believe that RNA, rather than DNA, was the first genetic material?

RNA has both information storage and catalytic properties.


The End Permian mass extinction, also known as the Permo-Triassic extinction event, or, The Great Dying, was the largest mass extinction event in the animal fossil record, with up 96% of all species dissapearing. Which set of circumstances did we discuss as being involved in potentially causing this extinction event?

ocean acidification in association with drastic increases in CO2 in the atmosphere


As we discussed in class, during various geological eras, vertebrate land predators and their prey repeatedly went through evolutionary arms races, so to speak, in which...

predators and prey both became more adapted to running behavior, with predators evolving from primarily ambush styles to pursuit predation


Which of the following statements best describes the fossil record of mammalian origins?

It includes transitional forms with demonstrating that middle ears bones evolved from bones in the jaw.


Part completeWhich of the following methods is the most accurate way to measure the age of a relatively recent fossil?

ratio of carbon-14 to carbon-12


Which of the following observations would provide evidence supporting Lamarck's proposed evolutionary mechanism of "inheritance of acquired characteristics"?

a decrease in tail length in dogs after 20 generations of dogs that had their tails docked (cut off) as puppies


Which of the following statements best describes Darwin's theory of evolution by natural selection?

Darwin's theory emphasized that populations vary and change over time.


Cotton-topped tamarins are small primates with tufts of long white hair on their heads. While studying these creatures, a scientist noticed that males with longer hair get more opportunities to mate and that they father more offspring than males with shorter hair. Which of the following possible studies would be the best design for testing if longer hair is an adaptive trait? Assume that hair length is a trait that is inherited.

unchanged vs. males with shortened hair.


Currently, two of the living elephant species (X and Y) are placed in the genus Loxodonta, and a third surviving species (Z) is placed in the genus Elephas. Assuming this classification reflects evolutionary relatedness, which of the following is the most accurate evolutionary tree?

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Which of the following statements best describes the effect of natural selection on a population?

improved match between a population and its environment


Continental drift (plate tectonics) has moved continents around the globe. Which of the following predictions would be most likely?

The most recently separated continents will have the most closely related species.


Over long periods of time, many cave-dwelling organisms have lost their eyes. Tapeworms have lost their digestive systems. Whales have lost their hind limbs. How can natural selection account for these losses?

Under particular circumstances that persisted for long periods, natural selection reduced each of these structures because they presented greater costs than benefits.


Structures as different as human arms, bat wings, and dolphin flippers contain many of the same bones, which develop from similar embryonic tissues. These structural similarities are an example of ________.



Which of the following statements is most accurate in comparing scientific theories and scientific hypotheses?

Scientific theories are supported by, and make sense of, many observations, whereas scientific hypotheses are narrow, testable ideas.


The evolution of analogous structures across different species of organism, that is, the evolution of structures that are similar strucurally and/or functionally in distant relatives that would not have existed in the common ancestor of those organisms, describes this process:

convergent evolution


Which of the following situations leads to microevolution?

Alleles move between populations that differ in allele frequencies.


Natural selection changes allele frequencies because some _______ survive and reproduce better than others.



Which of the following statements is accurate with regard to a population in Hardy-Weinberg equilibrium?

Allele frequencies should not change from one generation to the next.


Which one of the following conditions would most likely cause allele frequencies to change by chance?

small populations


A researcher has maintained a small population of fruit flies in the laboratory by transferring the flies to a new culture bottle after each generation. After several generations, the viability of the flies decreased greatly. Recognizing that small population size is likely to be linked to decreased viability, which of the following approaches would be the best way to reverse this trend of decreased viability?

cross the flies with flies from another lab


Which of the following results is the most likely outcome of increased gene flow between two populations?

decreased genetic difference between the two populations


An earthquake decimates a ground-squirrel population, killing 98% of the squirrels. The surviving population has broader stripes, on average, than the initial population. If broadness of stripes is genetically determined, which of the following processes most likely caused the change?

a bottleneck effect


What is the only evolutionary mechanism that consistently leads to adaptive evolution?

natural selection


Which of the following factors is the primary criterion for determining species boundaries when applying the biological species concept?

gene flow


Two species of frogs belonging to the same genus occasionally mate, but the embryos stop developing after a day and then die. Which of the following mechanisms keep the species separate?

reduced hybrid viability


Recently, a museum scientist discovered a case of preserved grasshoppers that do not resemble any named species. No information about when and where the specimens were collected is available. Which of the following species concepts would be most appropriate to use in identifying and naming the new specimens?



Which of the following provides an example of a mechanical isolation as a prezygotic barrier?

two snails have shells that spiral in different directions


In the oceans on either side of the Isthmus of Panama are 30 species of snapping shrimp, 15 species on the Pacific side and 15 different species on the Atlantic side. Species live at different water depths. Morphological and genetic data show that Atlantic and Pacific species that live at similar depths are sister species. Geological evidence indicates that the Isthmus of Panama started rising about 10 million years ago and the oceans were completely separated by the isthmus about 3 million years ago. Which of the following statements would best explain why the shallow-water sister species are more similar to each other than are the deeper-water species?

The shallow-water sister species have been geographically isolated from each other for a shorter time than the deep-water sister species have been.


Plant species A has a diploid chromosome number of 12. Plant species B has a diploid number of 16. A new species, C, arises as an allopolyploid from A and B. The diploid number for species C would probably be



In the western United States, pronghorn antelopes and domestic cattle often associate with one another in the same open rangeland. In a hypothetical situation, a certain species of flea originally fed only on pronghorn antelopes. Some of these fleas developed a strong preference for cattle blood and mated only with other fleas that also preferred cattle blood. The host mammal can be considered as the fleas' habitat. Which of the following processes most likely occurred if the situation persisted and a new species evolved?

sympatric speciation and habitat isolation


Which of the following outcomes is most likely in hybrid zones where reinforcement of isolating mechanisms is occurring?



According to the __________ model, morphological change occurs in spurts; species evolve relatively rapidly then remain unchanged for long periods.

punctuated equilibrium


Which of the following statements supports the hypothesis of “an RNA world” on early Earth?

Some RNA molecules are important catalysts in modern cells.


Which of the following molecules was most likely the first genetic material on Earth?

Which of the following molecules was most likely the first genetic material on Earth?


Earth probably formed __________ years ago, and the first life evolved as early as __________ years ago.

4.6 billion, 3.9 billion


Which of the following organisms would be most likely to form a fossil?

a common turtle


The earliest organisms were most likely __________.


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What was the “oxygen revolution,” which took place 2.3 billion years ago?

The “oxygen revolution” was the rapid increase in atmospheric oxygen that took place 2.3 billion years ago, dooming many prokaryotic groups.

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The figure shows eyes found among living molluscs, ranging from a patch of pigmented cells in a limpet to a complex, image-forming eye in a squid. Is it possible that a structure as complex as an image-forming eye evolved by natural selection?

s, if the photoreceptor cells and simple eyes that preceded it were useful to the animals in which they arose.


Which of the following statements best explains the existence of evolutionary trends, such as increasing body sizes among horse species?

In similar environments, similar adaptations can be beneficial to more than one species.