Lecture Exam 1

How many chromosomes would be found in an allopolyploid plant if its parents had diploid numbers of 2 and 10, respectively?

Haploid number of 6

How did Dr. Allison test his hypothesis that sickle cell disease was connected to malaria?

He evaluated blood samples for malaria parasites and the presence of sickle cells. He expanded his study area beyond Kenya to the rest of East Africa to see if malaria and sickle disease were connected.

_____ were the dominant vertebrate life form during the Mesozoic era.

Dinosaurs

What prevents speciation from occurring in sympatric populations?

Gene flow

Which discovery supports the hypothesis that evolution of the lactase-persistence trait was driven by the use of milk in pastoralist cultures?

Ancient pots used to hold milk are about the same age as the lactase-persistence mutations.

Prokaryotic cells are found in the domain(s) _____.

Bacteria and Archaea

Suppose that a gene for coat color in mice has two alleles, B and b, where B is completely dominant and encodes a black coat color, and b is recessive and encodes a brown coat color. A mouse that is heterozygous has genotype _____, and its phenotype is _____.

Bb; black

No two species of anoles lizards living in the same geographical location have dewlaps of the same size, shape or color. Why?

Dewlap color is under strong selection. Dewlaps that contrast with a lizard's environment are more effective for communication. Female anole lizards distinguish males of their own species from males of other species by their dewlaps. Male anole lizards use dewlaps to court females. Differences in dewlaps keep different anole species reproductively isolated, even when they live together.

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.

DNA evidence suggests that anole lizard species from the four largest Caribbean islands are related as shown in the figure. Which statement is true?

Different body types evolved repeatedly and independently on each island.

Different finch species have beaks of different shapes and sizes. What do these beak differences tell us?

Different finch beak shapes are evidence that finch species adapted to different environments over many generations.

What is the most important characteristic of anole lizard species that keeps members of one species from mating with members of another species?

Different species living in the same habitat have different dewlaps.

How does Dr. Allison's work provide an example of natural selection in humans?

In areas with malaria, individuals with one sickle cell allele reproduced at higher rates than those with no sickle cell alleles. In areas without malaria, individuals with two sickle cell alleles reproduced at lower rates than those without sickle cell disease.

How does continental drift affect living organisms?

It causes climate change, which puts selective pressure on organisms. It causes changes in habitats, such as when large amounts of shallow marine habitat were lost in the formation of Pangaea. It may cause an increase or decrease in competition among different species. It happens so slowly that it does not affect living organisms. All but one of these are correct.

What did researchers discover about the genetic mutation causing lactase persistence?

It is found in a regulatory region (a "switch") upstream of the lactase gene.

What 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.

How could milk-drinking have provided strong favorable selection for lactase persistence?

Milk was safer to drink than water and reduced exposure to pathogens. Milk is protein and fat-rich and therefore could have been an important, high-quality food source. Milk may have been a critical food source during times of famine.

In the five-kingdom system, prokaryotes are placed in the kingdom _____.

Monera

In 1977, medium ground finches on Daphne Major experienced a severe drought. The figure shows the beak depths of the initial population before the drought (red bars) and of the drought survivors (black bars). What do the data show?

More than one-half of the initial population died during the drought. Finches with larger beaks had a survival advantage in the 1977 drought. The most common beak size of the initial population was 8.8 millimeters. A very small proportion (~5%) of the initial population with this beak size survived.

For 1981, 1987, and 1990, how does the frequency of left-mouthed breeding adults compare to the frequency of left-mouthed individuals in the entire population?

Most of the breeding adults had the opposite phenotype of that which was most common in the population.

When Charles Darwin set sail on the HMS Beagle, what did he and most of his contemporary scientists think about the origin of species?

Most scientists, including Darwin, thought each species was specially created by God in its present form and did not change over time.

Which of the following evolutionary forces could create new genetic information in a population?

Mutation

Small Aristelliger lizards have difficulty defending territories, but large lizards are more likely to be preyed upon by owls. Which kind of selection acts on the adult body size of these lizards?

Stabilizing selection

Women often have complications during labor while giving birth to very large babies, whereas very small babies tend to be underdeveloped. Which kind of selection is most likely at work regarding the birth weight of babies?

Stabilizing selection

Which term is used to describe populations that live close enough to interbreed?

Sympatry

What would be the ploidy of the viable gametes produced by a tetraploid individual if nondisjunction of all chromosomes occurred in meiosis I?

Tetraploid

In the United States today, about half of the corn crop is genetically engineered with a protein that is toxic to corn borers, an insect pest of corn. Which of the following conditions would be necessary for evolution of resistance to the toxic protein to occur in the corn borer?

The corn borer must have or generate (by mutation) heritable variation in resistance to the toxic protein. The resistant corn borers must survive better or reproduce more than nonresistant corn borers

Which of the following statements describes the evolution by natural selection of Mycobacterium tuberculosis bacteria in their new environment?

The drug-resistance trait is an adaptation to the environment in which human hosts are medicated with the antibiotic rifampin

What genotype frequencies are expected under Hardy-Weinberg equilibrium for a population with allele frequencies of p = 0.8 and q = 0.2 for a particular gene?

The expected genotype frequencies are 0.64, 0.32, and 0.04 for A1A1, A1A2 , and A2A2 , respectively.

Which of the following observations led to Darwin's major inferences?

The first and fourth answers are correct. (Members of a population vary in their heritable traits / although organisms can produce huge numbers of offspring, many of these offspring do not survive)

Which of the following is an example of the pattern of evolution?

The fossil record of the evolution of modern cetaceans

Which observations led Darwin to establish a relationship between extinct and living animals?

The fossilized remains of giant sloths were found in places where smaller sloths now live. The bony shells of armadillos resembled the shells of ancient Glyptodon fossils

What is the frequency of the A1 allele in a population composed of 20 A1A1 individuals, 80 A1A2 individuals, and 100 A2A2 individuals?

The frequency of the A1 allele is 0.3.

A group of small fish live in a lake with a uniformly light-brown sandy bottom. Most of the fish are light brown, but about 10% are mottled. This fish species is often prey for large birds that live on the shore. A construction company dumps a load of gravel in the bottom of the lake, giving it a mottled appearance. Which of these statements presents the most accurate prediction of what will happen to this fish population?

The proportion of mottled fish will increase over time.

Varieties of Staphylococcus aureus that are resistant to the drug methicillin _____.

The second and fourth answers are correct. (Already existed in the population before methicillin was developed / Were strongly selected for as methicillin became widely used to treat bacterial infections)

Predict what will happen to the frequency of the sickle cell allele in areas where malaria has been eradicated.

The sickle cell allele will decrease in frequency.

In a bell-shaped curve, the x-axis (horizontal direction) of the graph represents which of the following?

The value of a particular characteristic; characteristics of an organism can include such traits as size and color.

As Wallace traveled the Malay Archipelago, he noticed that western islands had placental mammals, like monkeys. Eastern islands had marsupial mammals, like kangaroos. How did Wallace explain this distribution?

The western islands were once connected to Asia and the eastern islands had been connected to Australia. The islands had never been connected to each other.

In the lab, Nachman examined dark mice from two different populations living hundreds of miles apart. The mice looked nearly identical. Their dark color was caused by two different genes. What does this tell you?

There are at least two genes involved in creating dark mouse fur. Two completely different mutations in two separate genes can generate the same phenotype. Dark fur color evolved independently on each lava flow. Under very similar conditions, natural selection can favor very similar adaptations.

Why do dark-colored rock pocket mice on dark lava flows have white bellies?

There is no selection for dark bellies by visual predators.

In the two-kingdom system, why were fungi classified in the kingdom Plantae?

They are sedentary.

Which of the following statements about autopolyploid individuals is true?

They contain more than two haploid sets of chromosomes.

Why did dark-colored rock pocket mice first appear in a population of light-colored rock pocket mice?

They have a genetic mutation that affects their fur color.

How did the Grants test their hypothesis that differences in birds' songs can keep different species of finches from breeding with one another?

They played the songs of medium ground finches and cactus finches through a loudspeaker to see which species responded to each song.

True or false? A flood that separates a population of frogs onto opposite sides of a lake is an example of a vicariance event that may result in allopatric speciation

True

True or false? Convergent evolution is said to have occurred if the mouse species on two islands with similar habitats are found to have similar characteristics even though they originated from different species that did not have these characteristics.

True

True or false? It would be difficult to assess whether the drug-susceptible or drug-resistant phenotype in a population of Mycobacterium tuberculosis was more fit in an environment without antibiotics.

True

True or false? The Hardy-Weinberg model makes the following assumptions: no selection at the gene in question; no genetic drift; no gene flow; no mutation; random mating.

True

Which Anolis lizard ecomorph has long legs?

Trunk/ground

The earliest organisms were most likely _____.

prokaryotic

Charles Darwin _____.

proposed natural selection as the mechanism of evolution

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

punctuated equilibrium

According to the Hardy-Weinberg theorem, the frequencies of alleles in a population will remain constant if _____ is the only process that affects the gene pool

sexual reproduction

Fossil evidence indicates that some dinosaurs had feathers. If birds are indeed descended from those feathered dinosaurs, feathers are what kind of character?

shared ancestral character

Sympatric speciation is _____.

the appearance of a new species in the same area as the parent population

According to the phylogenetic species concept, what is a species?

a set of organisms with a unique genetic history

Consider the following mutations to the nucleotide sequence of a gene. Which of these mutations would not alter the reading frame of the gene's genetic message?

a single nucleotide-pair substitution

An adaptation is _____.

a trait that gives an organism a reproductive advantage in the current environment

Animals that possess homologous structures probably _____.

evolved from the same ancestor

Feathers either play a role, or may have played a role, in _____.

flight gliding courtship extended hops all of these

What situation most likely explains the occasional high frequency of certain inherited disorders among human populations established by a small population?

founder effect

A certain species of salamander was split into two populations by a wide, dry valley, and the populations began to diverge from each other. After a period of time, some members of the two populations began to interbreed in a hybrid zone at the southern end of the valley. Only weak reproductive barriers existed by this time, so the two populations could freely interbreed and re-establish gene flow. This outcome in a hybrid zone is known as _____.

fusion

The enzyme lactase breaks the sugar lactose into which compound(s)?

galactose glucose

What process actually increases the number of genes in an organism's genome?

gene duplication

What is the most important factor that holds a gene pool of a species together and prevents speciation?

gene flow

One of the following is NOT a source of genetic variation.

genetic drift

A windstorm transports a few seeds of a plant species from Island A, where the species is abundant, to Island B, where prior to this event the plant species was not found. The environmental conditions on the two islands are very similar, but the islands are located far away from one another. Over time, a small population of this plant becomes established on Island B. A biologist samples plants on both islands and finds that allele frequencies on Island A differ substantially from allele frequencies on Island B at several genetic loci not known to affect survival or reproduction. Based on this information, the observed genetic changes mostly likely resulted from

genetic drift.

Which of the following can promote allopatric speciation but not sympatric speciation?

geographic isolation

Which of the following is the first step in allopatric speciation?

geographic isolation

Which process occurred frequently in the early history of the three domains on Earth, and makes determining phylogenetic relationships of that time difficult?

horizontal gene transfer

The genome of an organism

includes all of the organism's DNA.

Evolution works by _____.

"tinkering" with existing structures

_____ were the dominant vertebrate life form during the Paleozoic era.

Amphibians

What is the frequency of the A1A2 genotype in a population composed of 20 A1A1 individuals, 80 A1A2 individuals, and 100 A2A2 individuals?

0.4

Identify the four postulates of natural selection.

1. Individuals in a population vary in the traits they possess. 2. Some trait differences are heritable. 3. Survival and reproductive success are variable among individuals in a population. 4. Individuals with certain traits are more likely to survive and reproduce.

Suppose a BB female mouse mates with a Bb male mouse. Which of the following represents the probabilities of each genotype occurring among their offspring?

1/2 BB, 1/2 Bb

The Mesozoic era began approximately _____ million years ago.

251

The Precambrian time began at least _____ million years ago.

4,600

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

4.5 billion years ago ... 3.9 billion years ago

The Cenozoic era began approximately _____ million years ago.

65

A farmer wishes to develop a strain of high-yield corn that is also resistant to drought. He has the following individuals from the current year's crop: Individual A—Yield: 179 bushels/acre; drought resistance: high Individual B—Yield: 220 bushels/acre; drought resistance: low Individual C—Yield: 185 bushels/acre; drought resistance: medium Individual D—Yield: 140 bushels/acre; drought resistance: high Individual E—Yield: 200 bushels/acre; drought resistance: medium Which of the following crosses would produce the highest corn yield with the highest resistance to drought?

A and E

What is genetic drift?

A change in allele frequencies caused by random events

Which of the following organisms could be produced by artificial selection?

A cow that produces a large quantity of milk

How does the term "lactase persistent" relate to the term "lactose tolerant"?

A lactase-persistent person is lactose tolerant.

In a species that has two chromosomes, suppose that a male has genotype aa for a gene on chromosome 1 and genotype bb for a gene on chromosome 2. If a female of this species has genotype AA for the gene on chromosome 1 and genotype BB for the gene on chromosome 2, which of the following represents the possible genotypes in a cell of their offspring?

Aa on chromosome 1, Bb on chromosome 2

Which term describes a trait that increases an individual's ability to survive in a particular environment?

Adaptation

_____ is rapid speciation under conditions in which there is little competition.

Adaptive radiation

Which of the following statements about adaptive radiation is correct?

Adaptive radiation occurs within a single lineage.

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

All of the above are correct: it is broad enough in scope to explain many observations it is supported by a massive body of evidence from many disciplines it is general enough to provide many testable hypotheses

Which of the following statements about descent with modification is false?

All similarities between organisms result from descent from a common ancestor.

After his journey on the HMS Beagle, Darwin made this now-famous sketch in his notebook. Which ideas does it represent?

All species are linked to one another by common ancestry All species are connected to one another in a "family tree." Species descend from other species just as naturally as children come from parents.

Darwin and Wallace independently arrived at the same conclusion that species change over time. Which observations supported their conclusions?

Bird families clustered geographically: cockatoos in the Malay Archipelago and Australia, macaws and hummingbirds in the Americas. The fossilized remains of giant sloths were similar to the smaller, living sloths Darwin encountered. Tortoises from different Galapagos islands have distinct shells. Mockingbirds from different Galapagos islands had subtle, consistent differences. Birdwing butterflies were found throughout the Malay archipelago, but species differed slightly from island to island. The bony shells of armadillos resembled fossilized shells from the extinct Glyptodon.

The Grants witnessed strong selection during droughts in 1977 and 1985. Compare the two droughts.

Both droughts resulted in changes to food sources that favored the survival of some medium ground finches over others. Both droughts events provided strong natural selection on medium ground finch populations.

Darwin and Wallace made independent observations in different parts of the world. Which statements are true?

Both witnessed nature up close and realized it was a battlefield with massive casualties. Both observed slightly different species on nearby islands and concluded that species could change over time. Both collected huge numbers of specimens and realized that individuals vary within species.

We are living during the _____era.

Cenozoic

Long necks make it easier for giraffes to reach leaves high on trees, while also making them better fighters in "neck wrestling" contests. In both cases, which kind of selection appears to have made giraffes the long-necked creatures they are today?

Directional selection

Black-bellied seedcrackers have either small beaks (better for eating soft seeds) or large beaks (better for hard seeds). There are no seeds of intermediate hardness; therefore, which kind of selection acts on beak size in seedcrackers?

Disruptive selection

Which type of selection tends to increase genetic variation?

Disruptive selection

A human is classified in domain _____ and kingdom _____.

Eukarya ... Animalia

A rose bush is classified in domain _____ and kingdom _____.

Eukarya ... Plantae

True or false? A mating between a tetraploid individual and a diploid individual produces biologically fit offspring.

False

True or false? Heterozygote advantage refers to the tendency for heterozygous individuals to have better fitness than homozygous individuals. This higher fitness results in less genetic variation in the population.

False

True or false? The evolution of different ecomorphs on the Caribbean islands is an example of stabilizing selection.

False

True or false? The last ice age produced many different species mainly because populations dispersed and colonized new habitats.

False

The wing of a bat is homologous to the _____ of a whale.

Flipper

Which of the following are basic components of the Hardy-Weinberg model?

Frequencies of two alleles in a gene pool before and after many random matings

In 1949, Dr. Tony Allison observed a high frequency of Kenyans carrying the sickle cell allele in coastal areas and near Lake Victoria, but a lower frequency in the highlands. What did he hypothesize?

He hypothesized that there was a connection between malaria and sickle cell disease.

Which term describes the ability of a trait to be passed on to offspring?

Heritability

Which of the following statements is an accurate combination of postulates 1 and 2 of natural selection?

Heritable variation exists for traits among individuals in a population

When dark-colored fur gives mice a 1% competitive advantage and 1% of the population begins with dark fur, in about 1000 years, 95% of the population will have dark fur. Which of the following statements is true?

If dark-colored rock pocket mice had a competitive advantage of 0.1%, it would take longer for 95% of the population to have dark fur.

A population of birds colonizes an area in which the insects upon which they feed live inside trees. Which of the following events accounts for an observed increase in average beak size in the bird population over time?

Increased fitness of large-beaked birds, leading to natural selection

Which of the following statements is an accurate combination of postulates 3 and 4 of natural selection?

Individuals experience differential success in their ability to survive or reproduce due to differences in certain traits

The film defines species as populations whose members don't interbreed. What keeps different Galápagos finch species from mating?

Individuals recognize and only respond to songs of their own species. Geographic isolation and different environments led to changes in traits that affected mating. Males only court females that have a similar beak and similar size.

In some populations, 1 in 500 people have sickle cell disease. What reason does the film give for why a potentially deadly, inherited disease is found at such high frequencies?

Individuals with one sickle cell allele are protected from malaria and do not have sickle cell disease, thus keeping the allele in the population.

How does diploidy help to preserve genetic variation?

It allows recessive alleles that may not be favored in the current environment to be preserved in the gene pool by propagation in heterozygotes.

Which pair of chickens should a farmer breed to produce larger chickens?

Large hen, large rooster

What do these comparisons suggest about when natural selection favored left-mouthed individuals over right-mouthed individuals?

Left-mouthed individuals were selected for when right-mouthed individuals were more common, and vice versa.

Which organisms are not examples of an adaptive radiation?

Mammals and reptiles in the post-dinosaur age

What did Wallace conclude from observing that the bones in manatee flippers look similar to the bones in a human arm and hand?

Manatees' arm and finger bones are evidence that manatees share a common ancestor with land mammals.

Genetic evidence supports which of the following explanations for the presence of 13 different finch species on the Galápagos islands?

Many years ago, a small population of a single finch species migrated to the islands and evolved into the current 13 species.

Which of the following statements about meiosis is correct?

Meiosis produces cells that differ genetically from the parent cell.

Dinosaurs went extinct during the _____.

Mesozoic

Flowering plants first appeared during the _____.

Mesozoic

Jonathan Losos and colleagues conducted experiments on small, hurricane-swept islands as "natural laboratories." Which of the following statements is true?

Natural selection can lead to rapid changes. The average leg length of lizard populations decreased within a few generations. Islands scrubbed by hurricanes allow researchers to introduce new lizard populations and observe their evolution. There are many small islands with similar environments, meaning that researchers can repeat their experiments and observations in several locations.

Why are the large finches now living on the Galápagos Islands different from the original source population from a nearby island?

Natural selection favored individuals that were more fit in the new environment. The separation of habitats reduced gene flow between the populations. Genetic drift occurred in the two populations. All three answers are correct.

Which of the following statements about natural selection is true?

Natural selection favors individuals that reproduce more than others

What does Dr. Carroll mean when he says, "while mutation is random, natural selection is not"?

Natural selection favors some mutations. Mutations for advantageous traits are more likely to be passed on to the next generation. Natural selection acts on traits.

Does the ability of a Mycobacterium tuberculosis cell to infect a new host depend on its drug-resistant phenotype?

No drug-susceptible cells and drug-resistant cells are equally likely to infect a new host

How can an allopolyploid plant become a biologically fit new species?

Nondisjunction event during mitosis

Which of these is an example of temporal isolation?

One species is nocturnal, and the other species is not.

Bony fish first evolved during the _____ .

Paleozoic

Most modern animal phyla evolved during the _____ era.

Paleozoic

Reptiles first appeared during the _____ era.

Paleozoic

Seed plants first appeared during the _____.

Paleozoic

Animals first appeared during the _____.

Precambrian

Life arose during the _____.

Precambrian

The first prokaryotic cells appeared during the _____.

Precambrian

In the five-kingdom system, which kingdom consists primarily of unicellular eukaryotes?

Protista

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

RNA has both information storage and catalytic properties.

Which of the following statements about reinforcement is true?

Reinforcement is a type of natural selection.

Four individuals measured their baseline blood glucose, then drank a litre of milk. They then measured their blood glucose levels at regular 15 minute intervals for 60 minutes. The results are shown in the graph below. Which individuals are lactase-persistent?

Sarah Peter

Which of the following evolutionary forces consistently results in adaptive changes in allele frequencies?

Selection

Compare sickle cell disease and malaria.

Sickle cell disease and malaria are both potentially lethal diseases.

What was the main selective pressure behind the evolution of different Anolis lizard species in the Caribbean?

Specific ecological niches

Which of the following statements is not a part of the Hardy-Weinberg principle?

The genotype frequencies in the offspring generation must add up to two.

Which of the following is(are) homologous to the bones in this image?

The image of the cat paw

Which observation supports the position of eukaryotes at the convergence of the "ring of life"?

The nuclear genome of eukaryotes contains genes from archaeans and from bacteria.

The top figure shows beak sizes of the 1976 finch population before the drought of 1977 (red bars) and after the drought (black bars). The lower figure shows the beak sizes of the offspring of the drought survivors in 1978. What do these figures tell us?

The overall beak depths of the 1978 offspring population are larger the original 1976 population.

If a person has two normal copies of the hemoglobin allele, which statements are true?

The person is susceptible to malaria. The person is homozygous at the hemoglobin locus.

Which of the following statements about the evolution of Anolis lizards in the Caribbean islands is true?

The phylogeny of ecomorphs on a given island reveals that adaptive radiation has taken place.

A subset of a population of birds leaves its habitat on the mainland and colonizes a nearby island. The birds, after a period of time, become reproductively isolated. The island sinks and the population of birds that lived on the island returns to its original habitat. Which of the following statements about these bird populations is true?

The populations will not be able to interbreed because they are different species.

Which one of the following researchers developed a theory of evolution that was very similar to Charles Darwin's?

Wallace

What observations and evidence have Jonathan Losos and his colleagues gathered to support the theory of natural selection?

When Losos and colleagues transplanted tree-dwelling anoles to small, hurricane-scrubbed islands without trees, the lizards evolved to have shorter legs after only a few generations. DNA evidence suggests that the different lizard body types (twig, grass, etc.) evolved independently on each of the four large Caribbean islands. On each of the four large Caribbean islands, Losos observed the same distribution of anole lizard body types.

Mutations are always __________.

a change in an individual's DNA

Suppose that a mutation for lactase-persistence occurred in each of the populations described below. In which populations would the mutation be more likely to increase in frequency over time because of natural selection?

a population that raises wheat and sheep

Mass extinctions create conditions that promote _____.

adaptive radiation

The appearance of an evolutionary novelty promotes _____.

adaptive radiation

The different finch species found on the Galápagos Islands probably arose as a result of _____.

adaptive radiation

Radiometric dating _____.

allows us to indirectly date fossils up to billions of years old based on minerals in surrounding volcanic strata

Suppose that two distantly related species live in similar environments and share a distinctive characteristic that facilitates survival in their environment but is not found in their immediate ancestors. Based on this information, this distinctive feature most likely represents

an analogous character.

The oldest fossils usually _____.

are found in the deepest strata

Which of the following has been shown to cause speciation most rapidly?

autopolyploidy

Systematists have used a wide variety of traits to reconstruct the phylogenies of particular groups of organisms. Which one of the following traits produces a good estimate of phylogeny? See Concept 26.3

biochemical traits gross morphological traits molecular traits behavioral traits (all of the above traits combined)

Two animals are considered members of different species if they _____.

cannot mate and produce viable, fertile offspring

Which of the following taxonomic categories contains all the others listed here?

class

In evolutionary terms, an organism's fitness is measured by its _____.

contribution to the gene pool of the next generation

Blue poppies native to China were grown at a plant-breeding center in California. The plants with the thickest leaves were most likely to survive and reproduce in the drier climate. After several generations, the percentage of thick-leaved plants had increased by 42%. This adaptation of the poppies to their new environment is due to _____.

directional selection

A challenge to traditional (pre-1860) ideas about species came from embryology, when it was discovered that _____.

embryos of dissimilar organisms, such as sharks and humans, resemble each other

Which of the following is an example of an adaptation in anole lizards?

long legs in the anole lizards that live primarily on the ground and tree trunks

Which of the following is found in eukaryotic cells but not in prokaryotic cells?

membrane-enclosed organelles

Evolution of shorter legs in anole lizards placed on small, hurricane-scrubbed islands is an example of which type of evolution?

microevolution

Generation-to-generation change in the allele frequencies in a population is _____.

microevolution

By definition a clade is _____.

monophyletic

The original source of all genetic variation is _____.

mutation

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

natural selection

Which of the following are causes of evolutionary change?

natural selection genetic drift gene flow mutation

Molecular clocks are based on the idea that _____.

on average neutral mutations arise at a constant rate

There is(are) _____ eukaryotic domain(s).

one

From his observations of organisms in the Galapagos islands, Darwin reasoned that _____.

organisms had adapted to new environments, giving rise to new species

Hybrid zones provide an opportunity to investigate _____.

the evolution of reproductive isolation

The evolutionary effects of genetic drift are greatest when _____.

the population size is small

Hox genes are thought to play an important role in the development of different morphologies because _____.

they provide positional information in the embryo

Miller and Urey's experiments that attempted to recreate conditions on early Earth were significant because _____.

they showed that organic molecules such as amino acids could be produced from inorganic molecules

The atmosphere of early Earth probably contained no O2 until the emergence of organisms that _____.

used water as an electron source for photosynthesis