Quiz 1 Study Guide

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

Hardy and Weinberg were trying to determine how and whether allele frequencies in a population change from one generation to the next,

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

A lactase-persistent person is lactose tolerant. ; A "lactase-persistent" adult continues to make the enzyme lactase and is able to digest (and tolerate) lactose.

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 mutation

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

Galactose Glucose

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

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

Mutation(Why: mutations, which are changes in a cell's DNA, can introduce new genetic information in a population.)

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 cause no change in the average of the population; extreme phenotypes (in this case, large and small babies) become less common.

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 causes no change in the average of the population; extreme phenotypes (large and small lizards) become less common.

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.(Why: the expected frequency of the A1A1 genotype is p^2=(0.8)(0.8)=0.64; the expected frequency of the A1A2 genotype is 2pq=2(0.8)(0.2)=0.32; the expected frequency of the A2A2 genotype is q^2=(0.2)(0.2)=0.4. To verify your calculations, confirm that the three frequencies add up to one.

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 p = (number of A1 alleles) / (total of all alleles) = [(2 ( 20) + 80] / [(2 × 20) + (2 × 80) + (2 × 100)] = 0.3.

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

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

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; These are the five assumptions of the Hardy-Weinberg model

Genetic Drift

random change in allele frequencies that occurs in small populations

A biologist observes that a particular plant species is found in a forest but not in a nearby meadow. She hypothesizes that the plants could grow in the meadow but are not found there because their seeds have yet to land in the meadow. Which of the following would be the most appropriate way to scientifically evaluate this hypothesis?

scattering seeds in several areas of the meadow and observing whether they start to grow

An adaptation is

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

disruptive selection

form of natural selection in which a single curve splits into two; occurs when individuals at the upper and lower ends of a distribution curve have higher fitness than individuals near the middle

Mircoevolution

generation to generation change in a population's frequencies of alleles

Allele frequencies in a gene pool may shift randomly and by chance. What is this random shift called?

genetic drift ; Genetic drift due to chance events that alter allele frequencies.

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 ; The calculation to determine the frequency of the A1A2 genotype is: 80 A1A2 individuals i(20+80+100) total individuals = 0.4, the frequency of the A1A2 genotype.

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: highIndividual B—Yield: 220 bushels/acre; drought resistance: lowIndividual C—Yield: 185 bushels/acre; drought resistance: mediumIndividual D—Yield: 140 bushels/acre; drought resistance: highIndividual E—Yield: 200 bushels/acre; drought resistance: medium

A and E

mutation

A change in a gene or chromosome.

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

A cow that produces a large quantity of milk.

Sexual reproduction

A reproductive process that involves two parents that combine their genetic material to produce a new organism, which differs from both parents

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

Adaptation

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 causes both extreme phenotypes (large and small beaks) to be favored over the intermediate phenotypes.

Which type of selection tends to increase genetic variation? Stabilizing Selection Direction Selection Disruptive Selection

Disruptive selection eliminates phenotypes near the average and favors the extreme phenotypes, resulting in increased genetic variation in a population.

Which type of selection tends to increase genetic variation?

Disruptive selection(Why: disruptive selection eliminates phenotypes near the average and favors the extreme phenotypes, resulting in increased genetic variation in a population.)

macroevolution

Evolutionary change above the species level.

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; it will result in more genetic variation

Directional Selection

Form of natural selection in which the entire curve moves; occurs when individuals at one end of a distribution curve have higher fitness than individuals in the middle or at the other end of the curve

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

Heritability

Identify the four postulates of natural selection.

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

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

Large hen, large rooster

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

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

Which of the following statements about natural selection is true?

Natural selection favors individuals that reproduce are more likely to be selected for than individuals who don.t survive or cannot reproduce.

stabilizing selection

Natural selection that favors intermediate variants by acting against extreme phenotypes

A group of researchers gathered data on the number of cliff swallow road kills they observed while driving between nest sites in Nebraska. The data cover a period of about 30 years and date back to the time when cliff swallows first started to nest under highway overpasses.As the graph shows, the number of road kills observed declined sharply over time. The data led the researchers to ask themselves this question: What caused this decline?

Researchers came up with numerous hypotheses that could explain why fewer cliff swallows were being killed on roads. Their hypotheses included the following:• Traits that help individuals avoid being hit by cars have evolved through natural selection in the cliff swallow population.• The population size of cliff swallows living near roads has decreased over time.• Scavenger population sizes have increased, and more road-killed swallows get eaten before they can be found.• The number of cars driving on these roads has decreased over time

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

Resistant varieties existed in the population but did not confer any advantage until the environment changed with the introduction of the drug methicillin.

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 and Peter ; both peter and Sarah's blood glucose levels both rose by more than 30 mg/dL, showing that their bodies digested lactose into glucose and galactose.

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

Selection; the only evolutionary force that consistently results in adaptation. Mutation without selection and genetic drift are random processes that may lead to adaptive, maladaptive, or neutral effects on populations

Not part of the Hardy-Weinberg principle?

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

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

A heritable trait is one that

is determined at least in part by genes passed from parents to offspring. ; If you had trouble with this question, review the following material: Transmitted from parents to offspring, genes are the units of inheritance. Thus, for an organism to inherit a characteristic or trait from its parent, that trait must be determined at least in part by genes. "Dominant" does not indicate that a trait is always inherited, but rather describes a version of a gene (allele) that is fully expressed in the phenotype of a heterozygote; an alternate allele whose phenotypic effect is not observed in a heterozygote is said to be recessive.

What do DNA evidence and the fossil record indicate are the ancestors of the living cetaceans, the mammalian group that includes whales, dolphins, and porpoises?

land-dwelling animals

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

microevolution(Why: Generation-to-generation change in the allele frequencies in a population is the definition of microevolution)

rapid reproduction

mutation rates are low in animals (1 in every 100,000 genes per generation) and high in bacteria (higher in viruses) Short generation times allow mutations to accumulate faster

Which of the following are causes of evolutionary change?

mutation, gene flow, natural selection, genetic drift

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

the fossil record of the evolution of modern cetaceans ; the fossil record contains observable data regrading both the morphological development and biogeographical distribution of early cetaceans.

Alternation of gene number or position

the type of life cycle that occurs in those plants and algae in the Archaeplastida and the Heterokontophyta that have distinct haploid sexual and diploid asexual stages. ... The haploid spores germinate and grow into a haploid gametophyte.