Exam 1 Review

The half-life of Carbon-14 is about 5700 years. You have found a fossil that you believe to be about 28,500 years old because it has _____ the normal (modern) expected ratio of Carbon-14

1/32

If the half-life of carbon-14 is about 5,730 years, then a fossil that has 1/16 of the normal proportion of carbon-14 to carbon-12 should be about how many years old?

22,900

You compare homologous nucleotide sequences between several pairs of species with known divergence times. A pair of species that diverged 1 million years ago has two nucleotide differences, a pair that diverged 2 million years ago has four nucleotide differences, and a pair that diverged 3 million years ago has six nucleotide differences. You have DNA sequence data for the same homologous gene in another pair of species where the divergence time is unknown. There are seven nucleotide differences between them. Based on your clock, when would you estimate that their line of ancestry diverged?

3.5 million years ago

Suppose 64% of a remote mountain village have earlobes that are completely attached to the side of head and must, therefore, be homozygotes for the recessive attached earlobe allele. If this population conforms to Hardy-Weinberg equilibrium for this gene, what percentage of the population must be heterozygous for this trait?

32%

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 flowering plants 4.origin of cyanobacteria

4, 1, 2, 3

Suppose 51% of a remote mountain village can taste phenylthiocarbamide (PTC) and must, therefore, have at least one copy of the dominant PTC taster allele. If this population conforms to Hardy-Weinberg equilibrium for this gene, what percentage of the population must be heterozygous for this trait?

42%

Galápagos flightless cormorants diverged from their flying relatives around 2 million years ago. By contrast, penguins diverged from the lineage of albatrosses and petrels (their closest relatives) around 50 million years ago. A team of molecular biologists recently found that there are 3 nucleotide differences in a non-coding region of DNA between flightless cormorants and double-crested cormorants. Based on this information, how many nucleotide differences do you expect in that same region of DNA, between emperor penguins and wandering albatrosses?

75

A paleontologist works at two different sites. At his inland site, he finds fossils of a type of unicellular algae at a density about 3 individuals/m2, within sedimentary rock with some igneous rock that he dates to about 800,000 years old. At the coastal site, in rocks of about the same age, he finds fossils of large predatory snails, also at an average density of 3 individuals/m2. What is the most likely conclusion the can be drawn from this?

800,000 years ago, the algae in the inland environment were likely more abundant than the snails were in the coastal environment

Which of the following is likely to evolve over time through natural selection?

A population of mosquitoes in southeastern Brazil which competes with populations of other species of mosquitoes for access to food

Which of the following is/are the best candidates to evolve by natural selection?

A population of termites of all different shapes and sizes.

According to this phylogenetic tree of hypothetical genera, are Motinus spp. more closely related to Acanthis spp. or Colpophyllium spp.?

Acanthis spp.

The appearance of photosynthetic prokaryotes lead to dramatic increases in oxygen levels on the Earth. This allowed for the evolution of which of the following?

Aerobic respiration, which converts chemical energy from organic molecules into adenosine triphosphate to fuel cellular activity

Assuming that the phylogenetic tree shown here is an accurate representation of evolutionary relationships, fins in both seals and cetaceans (shown here inside the dashed box) are..

An analogous structure that is the result of convergent evolution

Both mammals and the archosaurs (shown here inside the dashed box) have a 4-chambered heart, while the rest of the amniotes have a 3-chambered heart. The 4-chambered heart in the mammals and archosausrs is...

An analogous structure that is the result of convergent evolution

Which of the following phylogenetic trees represents different evolutionary relationships than the rest

B

Which of the following is the correct way to write the scientific name of the Gray wolf?

Canis lupus

Manatees and dolphins are both marine mammals that occur in the Tampa Bay region. Like all mammals, they produce milk to feed their young, and like other placental mammals, their young develop inside the mother's reproductive tract with a complex and long-lived placental connection. Both species also display adaptations that are unique to marine mammals, including a flattened caudaul fin, or fluke, used for propulsion. Based on the most current information, manatees are in the order Sirenia, which is most closely related to the order Proboscidea which includes elephants. On the other hand, dolphins are in the suborder Cetacea which is most closely related to the suborder Artiodactyla which includes hippopotamuses. Cetacea and Artiodactyla are grouped together in the order Cetartiodactyla. Based on this information, you should conclude that:

Flukes evolved independently in the cetaceans and sirenians via convergent evolution.

Tunas are some of the fastest marine fishes, with speeds of up to 75km/hour. They can achieve this largely because of their stiff, torpedo-shaped body and skinny, crescent shaped tail fin which makes for very efficient swimming. All else being equal, fast swimming speeds are generally advantageous for fishes, as it allows individuals to catch more prey and escape predators more readily. Given this, why has natural selection not led to all fish being torpedo-shaped with a skinny crescent tail?

For some species, the costs of having such a body shape (e.g. being less maneuverable) may outweigh the benefits of it

What is the relationship between genetic variation in populations and natural selection?

Genetic variation must exist in populations before natural selection can occur.

Giraffes have exceptionally long necks among ungulates, and their necks are much longer than their nearest relative, the okapi. The most likely reason that giraffes develop this neck is:

Giraffes have the same number of vertebrae as other ungulates, but in the lineage that gave rise to giraffes there was a genetic mutation which allows for prolonged growth of the cervical vertebrae during embryonic development. Therefore, giraffe embryos look very similar to okapi in early stages of development.

While comparing DNA sequences to build a phylogenetic tree of bacteria, Jennifer finds a confusing piece of data: one population which would otherwise fit nicely into a particular clade seems to contain at least one very long DNA sequence that matches to that of a very distantly related clade. What process is most likely responsible for this mystery?

Horizontal gene transfer

Which tree shows a relationship between basidiomycetes and ascomycetes that is different from the other trees?

I

Hooded seals display sexual dimorphism, meaning that males and females look different. Only the males have a "hood" on their head, and can inflate their nasal septum in courtship displays. The presence of these features in male hooded seals is likely the result of...

Intersexual selection

Slugs evolved from ancestors that had a shell, which can help avoid predation. Given this, why is it that modern slugs do not have shells?

Loss of shell could be due to selection against shells in the lineage that gave rise to slugs, because some shell-less individuals avoided predation through camouflage and did not spend energy building shells

Which is an example of intrasexual selection?

Male elk compete for female mates by interlocking their antlers and pushing each other

You are contacted by a biologist with the Jamaican government, who has access to a large collection of shells that came from marine snails collected on local coral reefs. She asks you to determine how many species are represented in the group. Employing which of the following approaches would be MOST useful for this task?

Morphological species concept

Which is an example of artificial selection?

New breeds of dogs being formed for ideal characteristics

Which of the following list is correctly ordered from broadest to narrowest?

Phylum, Class, Order, Family

Charles Darwin would have been likely to agree with which of the following statements?

Populations can evolve if certain individuals have traits that give them greater survival or reproduction

Which of the following is correct?

RNA can perform enzymatic functions inside cells

The blood of humans still carries evidence of where life on Earth evolved. Which of the following is most likely to be that evidence?

Sodium and chloride from oceans

Which of the following is correct?

Some organelles of eukaryotic cells have DNA that is similar to some modern prokaryotes

You decide to go on to graduate school and study the mating behaviors of armadillos in Southwest Texas. You find that among all the armadillos in the area, some of them only exhibit mating behaviors and fertility in the spring, and the rest exhibit their mating behaviors and fertility in the fall. You make an argument in your thesis that these two sub-groups are likely to become separate species in the future. What is your best argument?

Temporal isolation

In a population of Sisserou parrots on the island of Dominica in the Caribbean, the gene for plumage color has two alleles, CG and CW. Individuals that are homozygotes for CW are white and suffer high mortality from predation. Individuals that are heterozygotes (CWCG) are light green in color and have a lower predation rate than white individuals. Individuals that are homozygotes for CG are dark green in color and blend in best against the dark jungle habitat, but they are also highly susceptible to avian psittacosis, a fatal infection caused by bacteria. In 2010, winds from Hurricane Tomas caused half the population of Sisserou parrots to colonize the nearby island of Martinique, leading to a healthy and large population on each island. Given that the bacterium that causes avian psittacosis is absent in Martinique, what do you expect will happen?

The CW allele will decrease in frequency in the Martinique population

In a population of geckos in Bali, Indonesia, the gene for eye color has two alleles, RG and RW. Individuals that are homozygous for RW have poor night vision. Individuals that homozygous for the RG allele have great night vision, but are susceptible to a fatal virus that infects lizard eyes. Individuals that are heterozygotes (RWRG) are have good night vision and are not susceptible to the eye virus. A tropical storm causes half the population of Geckos to colonize the nearby island Java, leading to a healthy and large population on each island. If the eye virus is absent in the Java population, what should you expect to happen?

The RW allele will decrease in frequency in the Java population

Machado-Joseph disease (MJD) is a rare inherited neurodegenerative disease in humans that causes progressive lack of muscle control and coordination of the upper and lower extremities. The symptoms are caused by a genetic mutation that results in an expansion of abnormal "CAG" trinucleotide repeats in the ATXN3 gene that results in an abnormal form of the protein ataxin which causes degeneration of cells in the hindbrain. Globally the incidence of MJD is fewer than 2 in 100,000 individuals. However, in some islands in the Azores (North Atlantic, off Portugal) and in Groote Eylandt (island off the north coast of Australia), the disease is much more prevalent, reaching rates of 0.7% and 5%, respectively. What is the most likely explanation for the higher prevalence of MJD in the Azores and Groote Eylandt?

The founder effect: the small number of humans that established the populations on these islands had a greater prevalence of the MJD-causing mutations that the worldwide average, due to chance

In a species of viper, an individual that is homozygous for the recessive skin color allele (cc) turns out yellow. The frequency of the c allele in an isolated population of vipers is determined to be 0.1. What should we predict to happen to the frequency of the c allele if we learn that the yellow color morph makes the individual vipers more sexually attractive than other color morphs?

The frequency of the c allele should become greater than 0.1

In a species of hamlet fish, an individual that is homozygous for the recessive color allele (cc) turns out brown, while those with one or two of the dominant allele C are red. The frequency of the c allele in an isolated population of hamlets is determined to be 0.2. What should we predict to happen to the frequency of the c allele if we learn that the brown color morph makes the individual hamlet less attractive to mates than the dominant red color?

The frequency of the c allele should become less than 0.2

Which of the following is a correct interpretation based on this tree?

The vertical axis represents time; primates and birds diverged from each other more recently than primates and ray-finned fishes, and therefore primates and birds are more closely related than primates and ray-finned fishes

A single gene with two alleles determines whether a ladybug has spots. Homozygous dominant ladybugs possess three spots, heterozygous ladybugs posses one spot, and homozygous recessive ladybugs do not posses any spots. You find that 36% of the ladybugs have three spots, 40% have one spot and 24% have no spots. You therefore conclude that:

This population is not in Hardy-Weinberg equilibrium and is evolving

Given an ancestor species with the DNA sequence TCTT and three decendent species with the sequences ACTT, AGTA, and AGTT, what is true of the different phylogenetic relationships represented below?

Tree 1 is more likely than the others based on this sequence, but a longer or different DNA sequence could change our understanding of which tree is most likely the correct representation

Among five species of plants (A-E), only species B, C and E have spines (shown below with an asterisk). If you know that the common ancestor of all five species did not have spines and you have no other information about theseplants, which of the following trees would you select as the most likely to reflect accurate evolutionary relationships between these species?

Tree 2

Among five species of insects (A-E), only species B, C and E have wings (shown below with an asterisk). If you know that the common ancestor of all five species had wings and you have no other information about these insects, which of the following trees would you select as the most likely to reflect accurate evolutionary relationships between these species?

Tree 4

True or false: The terms evolution and natural selection are interchangeable

True

A mutation occurs in the coding region of a gene responsible for producing protein channels in cell membranes in a protozoan. Though the mutation occurs in the coding region of the gene, the new mutant codon still codes for the same amino acid, and the mutant protein channel is the same shape as the wildtype. How should we expect this mutation to affect the evolution of this population? This allele should increase the fitness of the protozoan and become more common in the population over time. This allele should decrease the fitness of the protozoan and become less common in the population over time. WRONG- This allele should not be expected to have any impact on the fitness of the protozoan and therefore is equally likely to become more or less common. The likelihood that this mutant allele becomes fixed in the population increases with decreasing population size

Two of the above

Speciation is most commonly caused by what process?

Two populations of one species become separated by a geographic barrier, and over time their gene pools diverge due to natural selection and/or genetic drift and/or mutations

In which of the following examples would speciation most likely occur?

Two populations of urchins begin releasing gametes at different times of the year, one in spring and the other in fall.

Over long periods of time, some animals that live in the deep sea have lost their eyes. How can natural selection account for these losses?

Under particular circumstances that persisted for long periods, eyes presented greater costs than benefits.

The ancestors of cetaceans (dolphins and whales) are mammals with hair. Hair helps insulate the body of mammals and allows many species to keep a warm and stable body temperature even in cold climates. However, modern cetaceans are hairless, even those that live in very cold water. How can natural selection account for this loss?

Under particular circumstances that persisted for long periods, hair presented greater costs than benefits.

Which would be an example of a postzygotic barrier of reproduction?

When a beluga and a narwhal mate, they produce a hybrid (a narluga) that is sterile

In your Biological Diversity course, you learn that animals should be grouped as shown in "tree 1" in the figure below. This is based on morphological data: species A and B have radial symmetry and species C, D and E all have bilateral symmetry. Further, species D and E have a shell, while no other species shown here have one. Your lab partner undertakes an undergraduate research project in which she sequences part of the genome of these species, and finds that species C and D have much more similar DNA sequences than either of them share with species E. Based on that information, she proposes that the phylogenetic tree should be revised as it "tree 2" below. Is this a reasonable suggestion?

Yes, as species that are more closely related have more similar nucleotide sequences. The presence of a shell in species D and E could be the result of convergent evolution, or shells may have evolved in the common ancestor of species C, D and E then subsequently lost in species C.

An archeologist digs into the side of a hill made up of sedimentary rock. She finds fossils of five different species, as shown below. With no other information besides the location of the fossils, which fossil is most likely the oldest?

Z

Three populations of crickets look very similar, but the males have courtship songs that sound different. What function would this difference in song likely serve if the populations came in contact?

a behavioral reproductive isolating mechanism

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

a common squirrel

Eukaryotic cells...

appeared around 1.5 billion years ago, from endosymbiosis of a bacterium inside an Archaea

Evolution...

can happen whenever any of the conditions for Hardy-Weinberg equilibrium are not met

In a very large population, a quantitative trait has the following distribution pattern. If there is no gene flow, the curve shifts to the right, and the population size consequently increases over successive generations, which of the following is most likely occurring?

directional selection

A population of butterflies on the island of Grenada, has many individuals which are generally yellow, with variations in color from very pale (almost white) to much darker (almost orange). In a storm, a few individuals are blown to the nearby island of Carriacou, and these individuals go on to build a new population there. However, the population in Carriacou has low diversity in color, with all individualsl being quite pale. The environment is quite similar on both islands. What most likely accounts for the difference in the Carriacou population compared to the Grenada population?

founder effect and genetic drift

A population of lizards live in a forest; 100 are green, 100 are brown, and 100 are orange. A forest fire occurs and 85% of the lizards die. The remaining lizards are all green and brown. After 25 generations the lizards are still green and brown; orange lizards never appeared in the population again. Which of the following best explains this phenomenon?

genetic drift

Multicellular eukaryotes first appeared...

in oceans, about 1.5 billion years ago

The first living organisms appeared....

in primitive oceans, about 3.8 billion years ago.

At the edge of two populations of snails, some individuals mate with each other to produce hybrids. This hybrid zone...

increases gene flow between the populations

A population of butterfly has two alleles for color: blue (b) and red (r). bb individuals are blue; rr individuals are red; heterozygotes are purple. Which of the following mechanisms could lead to appearance of a new allele in this population (e.g. y for yellow)?

mutation

A population of roses has two alleles for color: yellow (y) and red (r). yy individuals are yellow; rr individuals are red; heterozygotes are orange. Which of the following mechanisms could lead to appearance of a new allele in this population (e.g. b for blue)?

mutation

In 1983, a population of dark-eyed junco birds became established on the campus of the University of California, San Diego (UCSD), which is located 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. Females have less white in their tails than do males, and display it less often. (Pamela J. Yeh. 2004. Rapid evolution of a sexually selected trait following population establishment in a novel habitat. Evolution 58[1]:166-74.)The UCSD campus male junco population tails are about 36% white, whereas the tails of males from nearby mountain populations are about 40-45% white. The founding stock of UCSD birds was likely from the nearby mountain populations because some of those birds overwinter on the UCSD campus each year. Population sizes on the UCSD campus have been reasonably large, and there are significant habitat differences between the UCSD campus and the mountain coniferous forests; UCSD campus has a more open environment (making birds more visible) and a lower junco density (decreasing intraspecific competition) than the mountain forests. Given this information, which of the following evolutionary mechanisms do you think is most likely responsible for the difference between the UCSD and mountain populations?

natural selection

A population of fish is exposed to a carcinogen dumped in the lake where they live. Most fish are completely unaffected by the chemical, while a small subset of individuals develop mutations, resulting in large morphological changes. Moreover, these fish with mutations are now infertile and have no offspring. Is this carcinogen leak likely to be a driving force for evolutionary changes in this population?

no

Researchers studying a small butterfly population note that some butterflies produce a toxin and other butterflies do not. They identify the gene responsible for toxin production. The dominant allele (T) codes for an enzyme that makes the toxin, and the recessive allele (t) codes for a nonfunctional enzyme that cannot produce the toxin. Heterozygotes produce an intermediate amount of toxin. The genotypes of all individuals in the population are determined (see below) and used to determine the actual allele frequencies in the population. Is this population in Hardy-Weinberg equilibrium? TT: 0.14 Tt:: 0.23 tt: 0.63

no

This phylogenetic tree represents relationships among the animals (the Metazoa). Vertebrates, the animals with a backbone, are a subphylum within the phylum Chordata. Based on that information, you should conclude that the group "invertebrates", the animals without a backbone, is...

paraphyletic

A group that includes homeothermic animals (shown here in the dashed box) is....

polyphyletic, and therefore not an appropriate taxonomic group

How can reproductive barriers form in sympatric populations while their members remain in the same geographic area?

polyploidy

Which of the following is required in order for two new species to evolve from a single species?

reproductive isolation

The first genetic material on Earth was probably ________.

self-replicating RNA molecules

A population of yellow peacock cichlid fish in lake Victoria utilizes elaborate courtship rituals, which involve males fighting other males and making specific swimming patterns that attract females. One season, a mutation causes some of the males in this population to change their courtship rituals, which now only attracts a certain genotype of female to mate. If this situation persisted indefinitely, what is the most likely long-term outcome?

sympatric speciation

Very early in development, snake embryos start developing limb buds, but development of limbs is quickly arrested and the limb buds disappear, leading to limbless adult snakes. Which of the following best explains how these limb buds disappeared?

the cells inside the limbs expressed genes that led to cell death

A storm separates a small number of butterflies in a migrating population. These butterflies end up at a destination different from where they usually migrate and establish a new population in this new area. The new population has a different gene pool and a lower genetic variation than the original population it came from. This is an example of __________.

the founder effect

Two species of dogfish belonging to the same genus occasionally mate, but the resulting embryo fails to develop and hatch. What is the mechanism for keeping the two dogfish species separate?

the postzygotic barrier called hybrid inviability

The biological species concepts defines a species as a group of individuals that can breed to create viable, fertile offspring. In which of the following cases can be it most readily applied to, to determine if two groups of organisms should be considered different species?

two groups of salmon that spawn in the same river in British Columbia

Darwin...

was the first, along with Wallace, to recognize that traits that confer higher survival and reproductive success become more abundant over time in a population