Upgrade to remove ads
Only $35.99/year

BIOL 2200 Exam 1

Terms in this set (73)

All known organisms transcribe genetic information to protein molecules via the same genetic code. This finding strongly supports the hypothesis that __________
all organisms are descended from a single common ancestor
A population of zooplankton is exposed to a small number of predatory fish that feed on the larger-sized (adult) zooplankton. Which of the following predictions would most likely occur based on the principles of natural selection?
Adult zooplankton will start to reach sexual maturity when they are still relatively small.
The upper forelimbs of humans and bats have fairly similar skeletal structures, whereas the corresponding bones in whales have very different shapes and proportions. However, genetic data suggest that all three kinds of organisms diverged from a common ancestor at about the same time.

Which of the following is the most likely explanation for these data?
Natural selection in an aquatic environment resulted in significant changes to whale forelimb anatomy.
Darwin originally defined evolution as _________
descent with modification
What does it mean to describe evolution as a scientific theory?
Evolution is a broad model that is supported by many observations and much experimental evidence.
In Darwin's view of descent with modification, _______
natural selection can improve the match between an organism and its environment
Even though rodents known as sugar gliders and flying squirrels are members of distinctly different groups of organisms and live on different continents, they possess similar characteristics.

This is an example of _________
convergent evolution
A(n) __________ is the smallest unit that can evolve.
population
Animals that possess homologous structures probably __________.
evolved from the same ancestor
Which of the following is not an observation or inference on which natural selection is based?
Poorly adapted individuals never produce offspring.
How did Hutton and Lyell's ideas influence Charles Darwin's thinking?
Darwin reasoned that the Earth must be very old and that slow, subtle processes could produce substantial biological changes.
How does our understanding of genetics today refute Lamarck's principle of the inheritance of acquired characteristics?
Experiments in genetics show that traits acquired during an individual's lifetime are not inherited in the way proposed by Lamarck.
Which of the following people developed the idea known as the scala naturae, or scale of nature?
Aristotle
The bacteria Staphylococcus aureus has developed resistance to some antibiotic drugs. How did this resistance come about?
Some members of the bacteria populations possessed some sort of genetic variation for antibiotic resistance that was selected for when the bacteria was exposed to the drugs.
Organisms found only in specific places in the world are referred to as __________
endemic
Which of the following is the best example of gene flow?
Wind blows pollen from one population of plants to another and cross-fertilization occurs.
Which of the following would seem to be an example of neutral variation?
Human fingerprints
No two people are genetically identical, except for identical twins. The main source of genetic variation among human individuals is _________
the reshuffling of alleles in sexual reproduction
In a population that is in Hardy-Weinberg equilibrium, 64% of the individuals express the recessive phenotype for a particular gene locus. What is the expected frequency of the recessive allele in this population?
0.8

The expected frequency of the dominant allele is represented by p, while the expected frequency of the recessive allele is represented by q. In this case, individuals expressing the recessive phenotype would possess the homozygous recessive genotype. The genotype frequency, q2, of these individuals is 0.64, so the frequency of the recessive allele q would be the square root of q2, which equals 0.8.
Which of the following can form entirely new alleles?
Mutation
Stabilizing selection __________
favors intermediate variants in a population
Point mutations in noncoding regions of DNA result in __________
neutral variations
Which of the following statements explains why male peacocks with brightly colored feathers are more prevalent than those with plain colors?
Female peacocks choose the showiest males as mates, causing this trait to be more prevalent in the population.
In a certain group of people, 4% are born with sickle-cell disease (homozygous recessive).
If this group is in Hardy-Weinberg equilibrium, what percentage of the group is heterozygous for the sickle hemoglobin allele?
32%

The 4% born with sickle-cell disease are homozygous for the sickle hemoglobin allele, so q2 = 0.04 and q = 0.2. Because p = 1 - q, p = 0.8. The heterozygotes would be equal to 2pq, or 0.32 (32%)
A population of squirrels is preyed on by small hawks. The smaller squirrels can escape into burrows. The larger squirrels can fight off the hawks. After several generations, the squirrels in the area tend to be very small or very large.

What process is responsible for this outcome?
Disruptive selection
Antibiotic resistance in bacteria is an example of which of the following?
Directional selection
Which type of selection maintains stable frequencies of two or more phenotypic forms in a population?
Balancing selection
A hurricane hits a small island, killing all but a few members of a bird population. This is an example of _________
the bottleneck effect
Which of the following sets of conditions is required for Hardy-Weinberg equilibrium?
Random mating, no natural selection, and a large population
Which of the following statements correctly describes a population in Hardy-Weinberg equilibrium?
Allele and genotype frequencies in the population will remain constant from generation to generation.
Which of the following is an example of a postzygotic reproductive barrier?
Two fruit flies of different species produce sterile offspring
The evolution of multiple species of snapping shrimp following the formation of the Isthmus of Panama is an example of __________
Allopatric speciation
A hybrid zone is defined as ________
a region in which members of different species meet and mate, producing at least some offspring of mixed ancestry
A new species of plant is discovered that closely resembles a known species. Upon further examination, it is discovered that the new species has a tetraploid number of 4n = 12, while the known species has a diploid number of 2n = 6.

Which of the following statements provides a reasonable explanation for the evolution of this new species of plant?
An error in cell division occurred in the known species, leading to the development of an autopolyploid tetraploid offspring that evolved into the new species.
Three species of sea stars all mate near the same reef by secreting their gametes into the water, but none of the gametes from the different species fertilize each other. This is an example of a __________ barrier called _________
prezygotic; gametic isolation
The behavior of a male blue-footed boobie during the courtship ritual elicits no response from the masked boobie. The reproductive barrier between them is an example of __________
behavioral isolation
When gene flow between two populations ceases, the potential for __________ exists
speciation
At which point in the adaptation of a population is it clear that speciation has occurred?
Gene pool changes establish reproductive barriers between two populations.
According to the punctuated equilibrium model of evolution, _________
the tempo of evolution consists of abrupt episodes of speciation among long periods of equilibrium
A horse and a donkey can reproduce successfully, producing a mule. However, the mule is sterile. This is an example of a __________ barrier called _________
postzygotic; reduced hybrid fertility
When gene flow between two populations ceases, the potential for __________ exists.
speciation
There are two groups of pine trees that appear to be very similar phenotypically and genotypically. However, one releases pollen in January, when the female structures of that group are receptive, and one in March.

What kind of reproductive barrier is this?
temporal isolation
In the case of the Lake Victoria cichlids, sympatric speciation has been shown to be driven by _________
sexual selection
Which of the following evolutionary mechanisms does not contribute to the process of allopatric speciation?
gene flow
The morphological species concept distinguishes species by _________
body shape and other structural features
Two different species of frogs mate successfully and produce fertile hybrid offspring. However, the offspring of the hybrids do not develop completely to adulthood. This is an example of which type of reproductive barrier?
hybrid breakdown
Which of the following reproductive barriers actually prevents individuals of closely related species from copulating successfully?
mechanical isolation
In which of the following groups has sympatric speciation been most important?
plants
According to the __________, a species is a group of populations whose members have the potential to interbreed in nature and produce viable, fertile offspring—but do not produce viable, fertile offspring with members of other such groups.
biological species concept
Imagine that part of a population of South American finches is blown by a storm onto an island far offshore and manages to survive and reproduce there for a period of 10,000 years. After that period, a climate change results in lower sea levels and the reconnection of the island with the mainland. Members of the formerly isolated island finch population can now interact freely with members of the original mainland population.

Which of the following observations would, by itself, lead you to conclude unequivocally that the island finch population had evolved into a distinct species, according to the biological species concept?
Individuals from the different populations sometimes mate with each other, but all of the resulting eggs are sterile
A new species of plant arises as an allopolyploid from two other plants, one with a diploid number of 14 and one with a diploid number of 18. What would the diploid number of the new species most likely be?
32
What evidence supports the hypothesis that mitochondria and plastids evolved from prokaryotic endosymbionts?
They have a single circular chromosome similar to bacterial chromosomes; their ribosomes are more like prokaryotic ribosomes than eukaryotic ribosomes
Single-celled prokaryotes had the Earth to themselves for approximately _________
1.5 billion years
Which of the following is a true statement concerning the history of Earth's biological diversity?
The majority of species that ever lived are now extinct.
The fossil record is _________
biased in favor of species that existed for a long time
Prior to the Cambrian explosion, all large animals had what characteristic in common?
They were all soft-bodied.
Which of the following is a true statement about the current status of Earth's biodiversity?
The current rate of extinctions is as high as 1,000 times the typical rate seen in the fossil record.
The original atmosphere of Earth had little oxygen. What was the likely first source of oxygen that led to an oxygen atmosphere?
cyanobacteria
Fossilized stromatolites _________
resemble structures formed by bacterial communities that are found today in some warm, shallow, salty bays
A genetic change that caused a certain Hox gene to be expressed along the tip of a vertebrate limb bud instead of farther back helped make possible the evolution of the tetrapod limb.

This type of change is illustrative of _________
a change in a developmental gene or in its regulation that altered the spatial organization of body parts
The principle of maximum parsimony is applied to the process of constructing a phylogenetic tree in what way?
The tree that requires the fewest evolutionary events, as measured by the origin of shared derived characters, is selected.
Sister taxa on a phylogenetic tree are defined as groups that _________
share an immediate common ancestor and are each other's closest relatives
Which of the following would be the least useful in determining the relationships among various species?
analogous structures
Which of the following best summarizes the neutral theory?
Darwinian selection does not influence a lot of evolutionary change in genes and proteins because many of these changes do not affect fitness.
What is the basis for the use of a molecular clock to determine the absolute time of evolutionary change?
Nucleotide substitutions in a gene occur at a relatively constant rate.
The separate lineages leading to dolphins and sharks both evolved streamlined bodies, dorsal fins, and broad tail fins as adaptations to efficient locomotion in a marine environment. In this comparison, the bodies and fins of dolphins and sharks are what type of structures?
analogous
Two genes are recognized as orthologous if __________
they are homologous genes found in different species, and their divergence traces back to speciation events that produced the species
The term polytomy refers to a situation in which __________
there is a branch point on a phylogeny from which more than two descendent groups emerge
In cladistics, biologists attempt to place species into groups that each include an ancestral species and all of its descendants. A group that is paraphyletic fails to accomplish this goal in what way?
It consists of an ancestral species and some, but not all, of its descendants.
A bald eagle and a black bear both have four limbs with digits because they are both tetrapods, descendants of a four-limbed ancestor. In this comparison, the limbs of the eagle and the bear are what type of structure?
homologous
A taxon ______
is a formal grouping at any given level
What is a primary reason why a three-domain taxonomic scheme has been adopted over the previous five-kingdom taxonomic scheme?
Phylogenies based on genetic data revealed that some prokaryotes (kingdom Monera) differ as much from each other as they differ from eukaryotes.
Researchers can use molecular homologies to _________
reveal the number of mutations in a particular sequence that has occurred in each species since they diverged from a common ancestor
Students also viewed