Bio questions
In a population of birds, wing feather pigmentation is determined by a single gene with two incompletely dominant alleles, A1 and A2. Suppose genotype A1A1 confers dark brown wings, genotype A1A2 is light brown, and genotype A2A2 is light beige. In a population of 1000 birds, 350 have dark brown wings, 500 have light brown wings, and 150 have light beige wings. What is the A1 allele frequency in this population?
.6
If one human protein contains 400 amino acids, how many nucleotides need to be in the exons of the corresponding gene to properly code for it?
1200
The fruit fly (Drosophila melanogaster) has four pairs of chromosomes. How many chromosomes would you find in an unfertilized egg (female gamete or sex cell) of this species?
4
An addition or deletion of one or two base pairs in a gene sequence results in a __________ mutation.
frameshift
Which statement best describes the phenomenon of "antagonistic pleiotropy" in evolution?
genes that affect more than one characteristic and have a negative effect on fitness in one context, but a positive effect in another
An adaptation refers to a __________.
hereditary trait that makes organisms more fit in their environment and that has arisen as a result of the action of natural selection
Charles Darwin's tree of life metaphor was used to describe
how a common ancestral species has diverged into many species, with the various branches illustrating the relationships among species and groups of species.
In order for traits to evolve by natural selection, individuals must experience differential reproductive success. This means that
individuals with certain traits are more successful than others in the population at surviving and reproducing.
A trait that serves one purpose today but evolved under different selective conditions and previously had a different function
is called an exaptation.
Natural selection requires that variation exists in a population and that the variation
is heritable.
The major genetic effect of inbreeding in a population is to increase the number of__________.
loci at which the average individual is homozygous
The modern theory of evolution, with natural selection as the mechanism for biological change, came from which of the following thinkers?
Charles Darwin and Alfred Russel Wallace
In sickle cell anemia, a point mutation leads to a replacement of one amino acid in a hemoglobin molecule, in a unit responsible for transportation of oxygen. This and any other mutation in a gene that causes a change in the amino acid sequence in a polypeptide chain is known as a __________ mutation.
missense
Variation is generated in a population primarily by
mutation.
In the southern European plains, a species of flower comes in two colors, purple and pink. When pink flowers are most common in a field, bees visit and pollinate the purple flowers more often, and vice versa. This switching of pollinator preference will result in __________.
negative frequency-dependent selection
The formal definition of "fitness" in evolutionary biology
pertains to reproductive success relative to other individuals in the population.
The figure shows the relationship between femur diameter and body mass for a wide range of animals. This figure highlights the surprising finding that there are no organisms with large bodies and thin legs. What type of constraint has caused this?
physical constraint on bone strength
Sometimes the relationships between taxa remain unresolved due to missing or conflicting data. For example, a node in the phylogeny of mammals might have three branches arising from it, leaving the evolutionary history of the placentals, marsupials, and monotremes uncertain. These nodes are represented on a phylogeny by a __________.
polytomy
Natural selection is a process by which the characteristics of a(n) __________ will change over time.
population
The purple flower of the F1 offspring of Gregor Mendel's parental generation crosses indicated that __________.
purple color in flowers is dominant to white color
One example of studying natural selection in the field comes from decades of work on life history strategies in the guppy, Poecilia reticulata. A species' life history strategy refers to the __________.
schedule and manner of investment in survivorship and reproduction over the lifetime of an individual
One constraint on what natural selection can achieve comes from the fact that it lacks foresight. This means that
selection favors changes that are immediately beneficial, not changes that may be useful sometime in the future.
Analogous traits are found in two or more species because
some evolutionary process (usually natural selection) has independently fashioned similar traits in each species.
As opposed to uniformitarianism, the approach known as catastrophism explains that Earth's geological features are a result of
sudden, cataclysmic, and large-scale geological events.
All of the following can help resolve a polytomy in a phylogeny, except more __________.
symplesiomorphies
Early Greek philosophers failed to exploit one of the greatest advantages of methodological naturalism, which is the ability to
test hypotheses through observation and sometimes manipulation.
Natural selection is a process that results in
the characteristics of populations changing over time.
Inbreeding depression is a reduction in the fitness of inbred individuals caused by__________.
the expression of recessive deleterious phenotypes due to increased homozygosity
From the late Middle Ages up to the seventeenth century, the written records of the Bible provided a starting place for mathematically estimating the age of Earth. Scientists began to understand the age of Earth was far greater than calculations based on the Bible. Which of the following scientists had the most influence on Charles Darwin regarding the ancient age of Earth?
Charles Lyell
The oldfield mouse study is a textbook example of hypothesis testing among natural selection (adaptation) studies. Which of the following is NOT correct regarding the main findings of this study?
Coat color in the oldfield mouse does not seem to have any adaptive value.
Bats and hummingbirds both have wings and can fly. This is due to__________.
Convergent evolution
Although scientists widely accepted Charles Darwin's theory of evolution and common descent, one of the major problems proposed and discussed was how to account for complex structures and multiple, intricate parts. Why was this seen as a problem?
Critics argued that Darwin's view of natural selection acting in gradual increments could not be responsible for forming complex structures and multiple, intricate parts because they had no value until fully formed.
Sunflower hybrids resulting from crosses between wild sunflowers and their domesticated relatives have high rates of survival. This would seem to suggest that the hybrids have a high fitness. However, before reaching this conclusion, you should next examine __________.
the number of offspring produced by hybrids.
The primary difference(s) between the processes of natural selection and artificial selection is/are
the selective agent and the traits being selected.
Which position in a codon shows the greatest degeneracy? In other words, if a change occurs in this codon position, it is less likely to change the amino acid that is specified relative to the other positions.
third position
All of the following are types of traits that evolutionary biologists might study in regard to natural selection EXCEPT
traits acquired during the lifetime of an organism.
A type of mutation in which a region of one chromosome is moved to a different chromosome is called __________.
translocation
A mutation that results in a replacement of a purine with a pyrimidine is known as a __________ mutation.
transversion
A mouse population contains hybrids between New Zealand Black (NZB) and New Zealand White (NZW) mice. NZW homozygotes are healthy, but NZB homozygotes experience autoimmune disease. NZB/NZW heterozygotes experience even more severe autoimmune disease (so much so that they are used as a model for the human autoimmune disease lupus). This situation is an example of __________.
underdominance
What is the difference between cladograms, phylograms, and chronograms?
what branch lengths represent
The figure shows a phylogeny of snakes and their relatives. Based on the information in this figure about which taxa are known to be venomous, why did Bryan Fry and his colleagues hypothesize that monitor lizards and iguanas would also be venomous?
If venomousness is homologous in snakes and Gila monsters, then others in the monophyletic group that includes these species also may have inherited this trait from their common ancestor.
According to the figure, which of the following statements regarding base substitution mutation rates is FALSE?
In viruses, base substitution mutation rates increase with increasing genome size.
Jean-Baptiste Lamarck was likely the first to propose a process for evolutionary change, and connected that process to environmental fit. However, he is most famous for his process being wrong. What was this process he proposed?
Lamarck proposed that characteristics were acquired during the lifetime of an organism as a result of the organism's habits and these acquired traits were passed down to their offspring.
What was one of the two primary distinctions between a "transformational" process of evolution, as described Jean-Baptiste Lamarck, and the "variational" process of evolution, as described by Charles Darwin?
Lamarck thought change was a result of differences acquired by members of a group and that the changes were acquired during the lifetime of the individual and passed down to their offspring. Darwin thought those differences already existed and were not acquired during the lifetime of the members of the group.
What was the primary difference in how Jean-Baptiste Lamarck and Charles Darwin explained the evolution of new species and the relationship among species?
Lamarck viewed relationships among species as linear chains, with each group independent of the other; Darwin viewed all species as interrelated due to common ancestry and believed that species sharing a more recent common ancestor more closely resemble each other.
How did Charles Lyell explain Earth's geological features?
Lyell said Earth's features were a result of the same processes currently observable, which have occurred over very long periods of time in a slow, gradual manner.
Which of Gregor Mendel's laws contradicts the blending theory of inheritance?
Mendel's first law, the law of segregation
The modern, or evolutionary, synthesis of Charles Darwin's theory is a result of our modern understanding of genetics. During the 1930s and 1940s, which two groups of scientists resolved their differences, ultimately resulting in the modern evolutionary synthesis?
Mendelians and Lamarckians
Consider two populations of fish that live in separate ponds, with no migration between them. How will mutation affect that degree of variation between these populations?
Mutation will increase the variation between populations.
The textbook examines in detail a study of the natural populations of guppies (Poecilia reticulata) in the waterfalls of Trinidad and Tobago. Upstream of such waterfalls, guppies typically face only mild predation pressure from one small species of fish. Downstream of the waterfalls, however, populations of guppies often are under severe predation pressure from voracious predators such as the pike cichlid. What life history strategy would be favored by natural selection in the upstream waterfalls?
Natural selection should favor females that can produce offspring that are relatively large and grow quickly.
In the guppies (Poecilia reticulata) of Trinidad and Tobago, natural selection may act differently in different locations of the waterfalls. Upstream of such waterfalls, guppies typically face only mild predation pressure from one small species of fish. Downstream of the waterfalls, however, populations of guppies often are under severe predation pressure from voracious predators such as the pike cichlid. What life history strategy would be favored by natural selection in the downstream waterfalls?
Natural selection should favor females that produce as many offspring as possible, rather than producing larger but fewer offspring.
The height of a yarrow plant (Achillea millefolium) depends on its genotype and the altitude at which it is raised. Suppose that one of the genotypes produces plants that are tall at low and high elevations and short at medium elevations. In this case, we would say that the genotype codes for the __________ in the yarrow plant.
Norm of reaction for height
The figure illustrates an evolutionary trade-off in binocular vision in birds. Which of the following is NOT true regarding the trade-off in this case?
Ostriches have better binocular vision than owls because their eyes are set on opposite sides of their head.
Which of the following statements about pedigrees and phylogenies is true?
Pedigrees tell us about the ancestry of individuals; phylogenies tell us about the ancestry of populations.
Natural selection acts on _______ differences in a population.
Phenotypic, not genotypic
At the molecular level, gene duplication often produces novelty in a lineage. This process provides another evolutionary pathway by which a protein can switch functions, without loss of the original function. What analytical approach helped the most to answer the question of evolution in the aldosterone-M receptor pair in the study by Jamie Bridgham and her colleagues?
Phylogenetic study
The phylogeny in the figure shows the relationships of pachyderms (elephants, rhinoceroses, and hippopotamuses) in relationship to other mammals. Based on this phylogeny, pachyderms are
Polyphyletic
Which of the following statements is true based on the phylogeny shown in the figure?
Primates are members of the Eutheria and Mammalia clades.
The Scottish author __________ presented a well-developed and widely influential theory on how new species originate from existing species in his 1845 book, Vestiges of the Natural History of Creation. He also thought about populations evolving rather than individuals.
Robert Chambers
Many mammals prefer mates that differ from themselves at the immune locus MHC. Why might this preference be advantageous for the offspring?
Such mating results in higher heterozygosity at the MHC locus, and therefore greater diversity in immune function.
Charles and Mary Brown found, in more than 30 years of studying cliff swallows (Petrochelidon pyrrhonota), that the number of swallow roadkill had significantly decreased and the average wing length of swallows in the population at large had decreased as well (Brownand Brown 2013). Which of the following scenarios could have resulted in these changes?
Swallows with shorter wings are more likely to survive in the face of oncoming vehicles, resulting in the population evolving shorter wings on average and dying less often as the result of road kill.
Taxonomy has long been an important field of biological science, with the goal of classifying organismal diversity. What has changed over the past 50 years in the way that biologists approach classification?
The Linnaean system of classification has been placed in a modern evolutionary framework by Willi Henning.
Consider two populations of fish that live in separate ponds and differ in the frequency of alleles at a locus. After a flood, the two ponds become connected by a stream and some fish are able to move between the ponds. What will happen to allele frequencies at this locus in the two populations?
The allele frequencies in the two ponds will become more similar to each other.
Richard Lenski and his colleagues have been tracking evolutionary change for more than 60,000 generations in the bacterium Escherichia coli (Le Gac et al. 2012; Wiser et al. 2012). According to the figure, which statement is NOT correct regarding their results?
The cell volume and fitness of the E. coli lines increased over time, but none of the lines experienced natural selection.
Richard Lenski's experimental E. coli populations have been used, among other things, to study constraints on what natural selection can achieve. In one set of experiments, the researchers found that the rate of adaptation was proportional to the supply of new variation available. This result highlights what type of constraint on natural selection?
The cell volume and fitness of the E. coli lines increased over time, but none of the lines experienced natural selection.
Charles Darwin recognized that Thomas Malthus' argument applies to animal and plant populations as well as to human populations. Look at the figure and choose which observation Darwin made from this.
The difference between the growth of a population and its size allowed by the food supply shows the possibility of selection through the struggle for existence.
What were Charles Darwin's two fundamental insights about the process of evolution?
The environment selects on variation in the traits of individual organisms, and all species have descended from one or a few common ancestors.
The phylogeny in this figure shows the evolution of visual opsins in tetrapods. Each colored triangle represents a different opsin. Which of the following accurately describes the opsins in these species?
The green opsin is a synapomorphy in baboons and humans, and the light blue opsin is symplesiomorphy in squamate reptiles and birds.
In the 1850s and 1860s, Gregor Mendel bred pea plants and examined the way that traits were passed down across generations. His conclusions, although not accepted during his lifetime, established the foundation for the field of genetics. Of the choices listed, what is the most relevant summary of Mendel's conclusions?
The hereditary factors responsible for traits such as seed shape and flower color are inherited as discrete units.
Charles Darwin believed that cranial sutures present in modern birds, reptiles, and mammals evolved prior to the evolutionary split between these three groups (see Figure 3.26). What is the best explanation for the evolution of this complex trait?
The original selective advantage of cranial sutures was probably to allow the rigid protective cranium to expand with a growing brain, and this function is retained.
What is the difference between the situations shown in the red and yellow lines?
The red line shows overdominance; the yellow line shows underdominance.
The graph shows the distribution of fitness effects of Bacteriophage f1 mutants. Note that values greater than 1.0 indicate beneficial mutations, whereas values less than 1.0 indicate deleterious mutations. What is the best conclusion from this study?
The vast majority of the mutations had a deleterious effect, but some were beneficial.
In his famous book Principles of Geology, Being an Attempt to Explain the Former Changes of the Earth's Surface, Charles Lyell stated that Earth's geological features were formed by the same currently observable processes taking place. Charles Darwin was greatly influenced by Lyell's work and proposed that the current diversity of life can also be explained by mechanisms that are in operation today, acting over very long periods of time. Why was this a critical understanding for both scientists?
They both understood that if currently observable processes acted in the same manner in the distant past, those processes could then be scientifically tested.
Do the phylogenies in the figure show the same or different relationships between taxa 1 through 4?
They show the same relationships because rotating the nodes in a phylogeny does not change the evolutionary relationships that they represent.
What did David Reznick and his coworkers do to test whether the life history strategies of the guppies (Poecilia reticulata) were indeed adaptations to their selection pressures in the upstream and downstream waterfalls of Trinidad and Tobago?
They transplanted guppies from high-predation sites below a waterfall to low-predation sites above a waterfall to test whether descendants of transplanted individuals evolved adaptations to their new selection.
What are homologous traits?
Traits that are found in two or more species because these species have inherited this trait from their common ancestor.
What is an important difference between transmission genetics and population genetics?
Transmission genetics deals with genotypes of individuals, while population genetics deals with genotype frequencies in a population.
The following tree is a chronogram of five orchid subfamilies, where the relative size of each subfamily's clade is proportional to the number of genera in it. Which of the following can you infer from this tree?
Two subfamilies of orchids underwent rapid diversification about 60 million years ago
Many models of the evolutionary consequences of mutation assume that the rate of back mutation is negligible. When is this a reasonable assumption?
When we are considering a protein where forward mutation leads to a nonfunctional protein and back mutation leads to a functional protein.
A phylogeny is __________.
a figure that shows the branching relationships among populations over evolutionary time
What do interior nodes on a phylogenetic tree represent?
a population that was the common ancestor of two or more descendant taxa
The figure shown is a phylogram—a phylogenic tree in which the branch lengths represent the __________.
amount of evolutionary change along each branch
In the interaction between predators and prey, we frequently observe prey becoming increasingly good at escaping predators, and predators increasingly good at capturing prey. This is an example of __________.
an evolutionary arms race
What is the term for a simultaneous action of natural selection on each side of the host-pathogen interaction?
an evolutionary arms race
Suppose that in wild rose plants, the A locus controls pigmentation of the flower petals. The A allele (for red flower coloration) is completely dominant to the a allele (for pale pink flower coloration). If purebred red-flowered plants were crossed with purebred pink-flowered plants, and their heterozygous offspring (the F1 generation) were grown so that such hybrids might be crossed among themselves, which of the following flower phenotypes might you expect in the F2 generation?
both red and pale pink roses (in a ratio of 3:1, respectively)
Gene expression in eukaryotes is strongly influenced by the local structure of the chromosome. In which of the following regions of a DNA molecule would you expect to find the highest levels of gene expression?
decondensed chromatin
One of the important facts learned from experiments in molecular genetics is that most amino acids can be encoded by more than one nucleotide triplet. For this reason, we say that the genetic code is __________.
degenerate
A mutation resulting in deletion of a protein-coding gene will most likely have a ___________ effect on fitness.
deleterious
What are vestigial traits?
Homologous traits that are functional in some related taxa but lack function in the taxon of interest.
Jean-Baptiste Lamarck hypothesized that changes acquired during the lifetime of an individual organism, as a result of adapting to its environment, are passed on to progeny. Why was this incorrect but still important?
Acquired traits are not heritable, but Lamarck's idea was important because he was the first to propose a process for evolutionary change and he connected it to environmental fit.
The idea of spontaneous generation has existed in human thought ever since the earliest written history. Such thoughts prevailed until the seventeenth century, when an Italian physician, Francesco Redi, tested the question on whether flies spontaneously generate from spoiled meat. Which of the following statements is FALSE regarding this experiment?
After the jars were covered with a mesh net, eggs and maggots were found in the meat
If the idea of natural selection was Charles Darwin's first insight on evolution, which of the following would best describe Darwin's second insight?
All species have descended from one or a few common ancestors; species that share a recent common ancestor tend to resemble one another in many respects.
The figure shows the relationships among vertebrates. Which of the following is true based on this phylogeny?
Amphibians are more closely related to birds than they are to lobe-finned fishes.
What is a scientific hypothesis?
An explanation of a phenomenon based on natural processes
Which of the following groups of taxa form a monophyletic group, according to the figure?
Artiodacyla, Canidae, Felidae
Suppose that you collected genotype frequency data from a natural population. If you found that the expected genotype frequencies differed significantly from your observed genotype frequencies, which of the following could you conclude?
At least one evolutionary process is operating in this population.
In their experiment in 1943 using E. coli, Salvador Luria and Max Delbrück tested two alternative hypotheses. The random mutation hypothesis and the acquired inherited resistance hypothesis make different predictions about the distribution of resistant mutants that will be observed upon exposure to bacteriophage (viruses that can infect and kill E. coli). Which of the following predictions, if proven, would support the acquired inherited resistance hypothesis?
At the time of exposure to the phage, all E. coli cells will be phage-sensitive. The process of exposure to the phage will induce phage resistance in a small fraction of the bacterial cells.
Why did the pre-Mendelian theory of blending inheritance pose a major challenge to Charles Darwin's theory of evolution by natural selection?
Blending inheritance would eliminate variation in a population
Which of the following is TRUE regarding the difference between a DNA molecule and an RNA molecule?
DNA is a double-stranded molecule, whereas RNA is a single-stranded molecule.
What was one of the ideas that separated Charles Darwin's On the Origin of Species as a complete, scientific explanation for evolution when compared to all other previous attempts?
Darwin articulated a mechanistic explanation for change in species over time and the match between organisms and the environment.
To explain how varieties were on the path to becoming new species, Charles Darwin introduced the concept of
Descent with modification
Which of the following examples best illustrates the concept of spontaneous generation?
During flooding, frogs spontaneously arise from mud
Evolution of complex traits, such as the production of milk in mammals and parental care, has been one of the difficult questions, both in theory and experimental studies. Which of the following best explains the evolution of complex traits?
Each intermediate step on the way toward the evolution of a complex trait was itself adaptive.
Charles Darwin's voyage across the Southern Hemisphere gave him an important insight to his theory that came from finding certain species and some fossils of their extinct predecessors in certain geographic regions. Which of the following was Darwin's conclusion that was essential in his theory and came from these biogeography evidences?
Each species arises only a single time in a single place, by descent with modification from a closely related species.
Which of the following statements is FALSE?
Epigenetic information cannot be passed down across generations.
The figure shows the relationships among featherless and feathered dinosaurs and birds. Based on this phylogeny, what can you say about the evolution of feathers?
Feathers are an exaption for flight.
Following an intense drought in 2000 to 2004, descendant populations of Brassica rapa flowered much earlier in the season than those from predrought populations. Researchers agreed that this could be a result of strong selection during these four years. For natural selection to act on flowering time in B. rapa, all of the following must be true, except
Flowering times must differ depending on the environment in which a plant is grown
Both Alfred Russel Wallace and Charles Darwin traveled extensively and were struck by the strong patterns they observed in the geographic distribution of nature's diversity. Which of the following observations did Wallace make?
Geographic features seem to play an important role in the clustering of similar, closely related species, and these similar species clustered together in time and space.
