Exam 4: Multiple Choice Questions – Flashcards

Which of the following is a fitness trade-off (compromise)? a. Hummingbirds are the best pollinators of certain flowers, but bees are the best pollinators for orchids. b. The strong, thick beak of a woodpecker helps it find insects in trees. c. In some hornbill species, the male helps seal the female in a tree with her nest until the young are ready to fledge. d. Turtle shells provide protection but are heavy and burdensome when moving.

A spontaneous mutation usually originates as an error in A) DNA replication. B) transcription. C) translation. D) protein degradation.

A mutation always causes a mutant phenotype. A) true B) false C) cannot be determined

Sexual reproduction is the main source of new alleles that natural selection acts upon A) true B) false

Lateral (or horizontal) gene transfer is the movement of genetic material between parent and offspring. A) true B) false

Every bacterial gene allele must be directly inherited from the parent bacterial cell via DNA replication. A) true B) false

Chromosome-level mutations can: A) duplicate an existing allele B) lead to deletion and loss of an allele C) guarantee that duplicated alleles are going to be different from each other D) A & B E) A, B & C

Mutations increase fitness A) always B) often C) rarely D) never

Which of the following is NOT a condition that must be met for Hardy-Weinberg equilibrium from generation to generation? (1 pt) A. Large population size B. No mutations C. No immigration or emigration D. Dominant alleles more frequent than recessive alleles E. No natural selection

If the frequency of two alleles in a gene pool is 90% A and 10% a, what is the frequency of individuals with genotype Aa in a population in Hardy-Weinberg equilibrium? (1 pt) A. 0.81 B. 0.09 C. 0.18 D. 0.01 E. 0.198

Name the 5 assumptions required for Hardy-Weinberg equilibrium in a population.

Which of the following describes the mechanism of gene flow? (1 pt) A. random mating B. migration C. genetic drift D. selection

If natural selection is NOT acting on a monogenic trait, then allele frequencies of the gene encoding for the trait remain constant. T/F

Gene flow always increases genetic variation. T/F

Random changes to allele frequencies due to events that do not depend on fitness do not lead to evolution. T/F

Genetic drift always occurs, but its effect on allele frequencies in very large populations is much less pronounced than in small populations. T/F

Evolution in a population of island iguanas can be caused by the following agent(s): a. Natural selection b. Gene flow c. Genetic drift d. All of the above e. Both natural selection and genetic drift.

For a biologist studying a small fish population in the lab, which Hardy-Weinberg condition is easiest to meet? a. no genetic drift b. no mutation c. random mating d. no selection e. no gene flow

In the Hardy-Weinberg equation, 2pq equals the percentage of _____. a. frequency of dominant allele b. expected frequency of homozygous dominant genotypes c. expected frequency of homozygous recessive genotypes d. frequency of recessive allele e. expected frequency of heterozygous genotypes

For biologists studying a large flatworm population in the lab, which Hardy-Weinberg condition is most difficult to meet? a. no genetic drift b. random mating c. no gene flow d. no mutation e. no selection

In 1986, a nuclear power accident in Chernobyl, USSR (now Ukraine), led to high radiation levels for miles surrounding the plant. The high levels of radiation caused elevated mutation rates in the surviving organisms, and evolutionary biologists have been studying rodent populations in the Chernobyl area ever since. Based on your understanding of evolutionary mechanisms, which of the following most likely occurred in the rodent populations following the accident? a. Mutation caused genetic drift and decreased fitness. b. Mutation caused the fixation of new alleles. c. Mutations caused major changes in rodent physiology over time. d. Mutation led to increased genetic variation.

Natural selection _____. a. can favor beneficial mutations b. does not affect harmful mutations c. is a random process d. creates beneficial mutations

A researcher wants to know if gene flow is contributing to evolution of drought tolerance of pitcher plants in a specific bog. As a control, she should a. Estimate the frequency of alleles relevant genes for drought tolerance. b. None of these. Gene flow does not contribute to evolution. c. All of the above. d. Determine if the population is in Hardy-Weinberg equilibrium. e. Transplant pitcher plants from other populations into the bog.

Mutation is the only evolutionary mechanism that _____. a. is more important in eukaryotes than in prokaryotes b. decreases fitness c. happens in all populations d. does little to change allele frequencies e. has no effect on genetic variation

Cystic fibrosis is a genetic disorder in homozygous recessives that causes death during the teenage years. If 9 in 10,000 newborn babies have the disease, what are the expected frequencies of the dominant (A1) and recessive (A2) alleles according to the Hardy-Weinberg model? a. f(A1) = 0.9700, f(A2) = 0.0300 b. f(A1) = 0.9997, f(A2) = 0.0003 c. f(A1) = 0.9600, f(A2) = 0.0400 d. f(A1) = 0.9800, f(A2) = 0.0200 e. f(A1) = 0.9604, f(A2) = 0.0392

Swine are vulnerable to infection by bird flu virus and human flu virus, which can both be present in an individual pig at the same time. When this occurs, it is possible for genes from bird flu virus and human flu virus to be combined. If the human flu virus contributes a gene for Tamiflu resistance (Tamiflu is an antiviral drug) to the new virus, and if the new virus is introduced to an environment lacking Tamiflu, then what is most likely to occur? a. The Tamiflu-resistance gene will undergo mutations that convert it into a gene that has a useful function in this environment. b. If the Tamiflu-resistance gene involves a cost, it will experience directional selection leading to reduction in its frequency. c. If the Tamiflu-resistance gene confers no benefit in the current environment, and has no cost, the virus will increase in frequency. d. The new virus will maintain its Tamiflu-resistance gene, in case of future exposure to Tamiflu.

Which of the following is a fitness trade-off (compromise)? a. Hummingbirds are the best pollinators of certain flowers, but bees are the best pollinators for orchids. b. The strong, thick beak of a woodpecker helps it find insects in trees. c. In some hornbill species, the male helps seal the female in a tree with her nest until the young are ready to fledge. d. Turtle shells provide protection but are heavy and burdensome when moving.

Over long periods of time, many cave-dwelling organisms have lost their eyes. Tapeworms have lost their digestive systems. Whales have lost their hind limbs. How can natural selection account for these losses? a. Natural selection cannot account for losses, but accounts only for new structures and functions. b. Natural selection accounts for these losses by the principle of use and disuse. c. Under particular circumstances that persisted for long periods, each of these structures presented greater costs than benefits. d. The ancestors of these organisms experienced harmful mutations that forced them to lose these structures.

Most Swiss starlings produce four to five eggs in each clutch. Starlings producing fewer or more than this have reduced fitness. Which of the following terms best describes this situation? a. stabilizing selection b. disruptive selection c. sexual selection d. directional selection e. artificial selection

Genetic drift occurs in a population. Which of the following statements might be true? a. Genetic drift decreased the population's fitness. b. Genetic drift increased the population's fitness. c. The population was relatively small. d. Any of the statements can be true. e. The population experiences a decrease in genetic variation.

Two frog populations (same species) living in two neighboring lakes sing slightly different courtship songs. Increased irrigation makes the land between the two lakes wetter, allowing frogs to expand their ranges to the area between the lakes. Females in both populations prefer loud frogs to quieter frogs, but do not distinguish between the two slightly different songs. Assuming that courtship song differences have a genetic basis, predict what will likely happen to the songs of the two frog populations. a. You cannot predict a change in the courtship songs at the two lakes. b. Genetic drift will cause the songs to differentiate even more. c. The songs will become more similar to each other. d. Males will become louder. e. Disruptive selection will cause the songs to differentiate even more.

A proficient engineer can easily design skeletal structures that are more functional than those currently found in the forelimbs of such diverse mammals as horses, whales, and bats. The actual forelimbs of these mammals do not seem to be optimally arranged because _____. a. natural selection has not had sufficient time to create the optimal design in each case, but will do so given enough time b. in many cases, phenotype is determined by genotype and the environment c. though we may not consider the fit between the current skeletal arrangements and their functions excellent, we should not doubt that natural selection ultimately produces the best design d. natural selection is generally limited to modifying structures that were present in previous generations and in previous species

Which of the following is the most predictable outcome of increased gene flow between two populations? a. increased genetic drift b. lower average fitness in both populations c. higher average fitness in both populations d. decreased genetic difference between the two populations e. increased genetic difference between the two populations

The Dunkers are a religious group that moved from Germany to Pennsylvania in the mid-1700s. They do not marry with members outside their own immediate community. Today, the Dunkers are genetically unique and differ in gene frequencies, at many loci, from all other populations including those in their original homeland. Which of the following likely explains the genetic uniqueness of this population? a. heterozygote advantage and stabilizing selection b. population bottleneck and Hardy-Weinberg equilibrium c. mutation and natural selection d. founder effect and genetic drift e. sexual selection and inbreeding depression

Which of the following is most likely to produce an African butterfly species in the wild whose populations show two strikingly different color patterns? a. stabilizing selection b. disruptive selection c. sexual selection d. artificial selection e. directional selection

When imbalances occur in the sex ratio of sexual species that have two sexes (that is, other than a 50:50 ratio), the members of the minority sex often receive a greater proportion of care and resources from parents than do the offspring of the majority sex. This is most clearly an example of _____. a. sexual selection b. frequency-dependent selection c. stabilizing selection d. balancing selection e. disruptive selection

Three-spined stickleback fish (Gasterosteus aculeatus) show substantial heritable variation in gill-raker length related to differences in their diets. Longer gill rakers appear to function better for capturing open-water prey, while shorter gill rakers function better for capturing shallow-water prey. Which of the following types of selection is most likely to be found in a large lake (open water in the middle and shallow water around the sides) with a high density of these fish? a. stabilizing selection b. directional selection c. sexual selection d. disruptive selection

Genetic variation _____. a. is created by the direct action of natural selection b. tends to be reduced by when diploid organisms produce gametes c. must be present in a population before natural selection can act upon the population d. arises in response to changes in the environment

Vestigial traits and neutral changes in DNA sequences are good examples of _____. a. nonadaptive traits b. acclimation c. convergent traits d. developmental homology e. adaptation