Biology 8. Evolution & Natural Selection – Flashcards

The appropriate unit for defining and measuring genetic variation is the: a) population. b) species. c) genome. d) mating pair. e) individual.

"Survival of the fittest" is a misleading phrase. Individuals with the greatest __________ ________ are the most fit in any population.

The consistent accumulation of mutations that creates differences in the DNA sequences of two diverging groups of organisms is referred to as: a) directional selection. b) the "hemoglobin regression." c) the founder effect. d) convergent evolution. e) a "molecular clock."

Most mutations: a) are beneficial to the organism in which they occur. b) are random, meaning that they only occur in small populations. c) are random, meaning they are unrelated to how useful or harmful they might be to the organism in which they occur. d) are in response to natural selection. e) migrate from one population to another.

Among the following group of organisms, which of the following would be considered the "fittest" organism? a) A small black spider that hatches 100 spiderlings b) A sterile light-colored rabbit in a light-colored habitat c) An overweight, smoking woman with four adopted children d) A man with low body fat exercises regularly, eats healthy, and is the biological father of a child. e) An older gentleman with a drug addiction but 10 children

Radiometric dating: a) makes it possible to determine the absolute age of fossils. b) measures the radioactive protons present in fossil-containing rocks. c) allows the fossils of organisms to be compared in terms of species types. d) does not make it possible to put the fossil record in order. e) is highly inaccurate.

Which of the following best supports the idea that the frequency of recessive alleles does not decrease over time? a) The dominant allele causes individuals to die off. b) Mutations alter the allele frequencies, making the dominant allele appear less frequently. c) Using Hardy-Weinberg equilibrium, it can be demonstrated that X allele frequencies will always produce the same genotype frequencies, retaining the allele frequencies. d) Genetic drift alters the allele frequencies, making the recessive allele more advantageous. e) There is no random mating in the population.

____________ selection favors organisms that have character values at both extremes of the phenotypic distribution.

Which of the following is a primary line of evidence demonstrating the occurrence of evolution? a) Fossil record b) Biogeography c) Comparative anatomy and embryology d) Molecular biology e) All of the above.

In a large population of randomly breeding foxes, a dominant allele results in a soft, brown pelt, while a recessive allele results in a rough, grey pelt. The dominant allele is found in 80% of the population while the recessive allele is found in 20%. There is no migration, drift, or selection in the population. When human beings enter this habitat, they selectively hunt foxes with brown pelts. After many generations of this activity, how will this population change? a) The total population size of foxes will increase, made up of mostly rough, grey-furred foxes. b) The frequency of the recessive allele will rise above 20%, while the dominant allele will decrease below 80%. c) The frequency of the recessive allele will decrease as the humans trap and kill more foxes. d) The allele frequencies or kinds of foxes in the population will stay the same. e) The dominant allele will disappear from the population within a few generations.

Which of the following types of selection is INCORRECTLY matched with its example? a) Stabilizing selection: Turkeys have been selected based on increased size of their breast muscles. b) Directional selection: Cows with the highest milk production are selected for breeding. c) Disruptive selection: The frequency of small and large fish among the salmon population increases. d) Stabilizing selection: Most babies born are between 7 and 8 pounds. e) Disruptive selection: Among salmon, the very large males and smallest, quickly swimming males mate with the greatest frequency.

Which of the following is incorrectly matched? a) Biogeography: Patterns in geographic distribution of organisms b) Comparative anatomy: Growth, development, and body structures of major groups of organisms c) Fossil record: Physical evidence of organisms from the past d) Laboratory and field studies: Implementation of the scientific method to observe and study evolution e) Molecular biology: Examination of life at the level of atoms and compounds

Which of the following proposed methods is most likely to give rise to a large population of smaller-than-average dogs after 20 generations? a) 1) Start with a large population of dogs of varying sizes. 2) When selecting the dogs to breed in order to generate a new generation, choose dogs in the lowest 20%, with respect to body size. 3) Repeat this for multiple generations. b) 1) Start with a large population of dogs of varying sizes. 2) When selecting the dogs to breed in order to generate a new generation, choose the smallest two dogs, with respect to body size, and have them produce as many litters as possible. 3) Continue mating the offspring of these litters for multiple generations. c) 1) Start with the two smallest dogs that you can obtain. 2) Have them produce as many litters as possible. 3) Repeat this for multiple generations. d) 1) Start with a large population of dogs of varying sizes. 2) When selecting the dogs to breed in order to generate a new generation, select random pairs of dogs. 3) Repeat this for multiple generations. e) None of the proposals above will give rise to a large population of smaller-than-average dogs. Natural selection can only occur in the wild.

Which of the following statements best describes artificial selection? a) Artificial selection results in greater numbers of mutated organisms due to its reliance on forced mutations. b) Artificial selection results after a large catastrophe strikes a region and results in the death of >90% of the individuals in a population. c) Artificial selection does not produce variable offspring. d) Artificial selection is not something seen in everyday life; it is, however, studied in highly sophisticated research labs. e) Artificial selection still exhibits differential reproductive success; however, mating and crossing is directed by humans and not nature.

Which of the following are true about marsupial mammals? a) They fill many niches in Australia that are occupied by placental mammals in other parts of the world. b) They are less fit than placental mammals. c) They have gone extinct as a result of the greater fitness of placental mammals. d) They are more closely related to each other than they are to placental mammals. e) Both the first and fourth answer choices are correct.

Which scientist is incorrectly matched to his scientific/evolutionary contribution? a) Georges Buffon showed that earth is much older than previously believed. b) Georges Cuvier showed through genetic experiments that extinction had occurred. c) Jean-Baptiste-Lamarck suggested that living species might change over time. d) Charles Lyell theorized that geological forces had shaped the earth and continue to do so. e) All of the above are correctly matched.

Which of the following is considered a result of natural selection? a) Adaptation b) New genes c) Artificial selection d) "Perfect" organisms e) Unchanged allele frequencies

Radiometric dating is useful in conjunction with the study of the fossil record because: a) radiometric dating of a species currently living on earth reveals how long the species has existed. b) radioactive fossils break down much more quickly than non-radioactive fossils. c) radioactive fossils break down much more slowly than non-radioactive fossils. d) it allows a determination not only of the relative ages of different fossils, but their absolute ages as well. e) radiometric data makes it possible to analyze the "soft parts" of extinct animals, filling in the gaps in the fossil record.

The chief concern among conservation biologists trying to protect small populations is: a) to preserve genetic diversity. b) that natural selection can only operate in large populations. c) that mutation rates are much higher in small populations. d) to reduce the duration of genetic bottlenecks. e) to maximize rates of allele fixation.

While on the voyage of the HMS Beagle, Darwin: a) studied Malthus's book Essay on the Principle of Population. b) wrote The Origin of Species. c) discovered a love for sea travel. d) nurtured his love of studying nature, exploring plant and animal diversity, and collecting fossils. e) corresponded extensively with Alfred Russel Wallace about their ideas on evolution.

Which of the following is NOT an important reason that natural selection does not lead to perfect organisms? a) Environments change quickly; natural selection may be too slow to adapt an organism in a population to the constantly "moving target" of the environment. b) Variation is created by random processes and natural selection can only "work" with the variations that show up. c) There are often multiple alleles for a trait; each allele may represent an equally fit "solution" to the challenges of the environment. d) All of the above are important reasons that natural selection does not lead to perfect organisms. e) None of the above is an important reason explaining why natural selection does not lead to perfect organisms.

Tiktaalik appears to: a) be a "living fossil" since it resembles many of the earliest fish, yet populations thrive today. b) be an extinct species of fish that was also able to fly due to flaps of skin between its fins. c) be a descendant of the one branch of ancestral horses that survived until today. d) represent a transitional species, somewhere between fish and land animals. e) be an extinct species of giant fish that was subject to strong selection for smaller body size.

Which statement best describes evolution? a) A change in genotypes in a population b) A change in allele frequencies in a population c) A change in phenotypes in a population d) An introduction of new alleles into a species e) A change in the phenotypes or genotypes of individuals

In the early 1800s when Darwin was growing up, it would have been difficult to develop a theory about how populations change over time because: a) almost everyone believed that humans and all other species, once created, could not change. b) no one had ever proposed that the earth was older than 6,000 years, so there was insufficient time for change to have occurred. c) almost everyone believed that organisms existed as groups of populations, not species. d) it was widely accepted that there was insufficient variation within any species to allow for change. e) no one had yet found a fossil having an obvious similarity to a living species.

During gene flow, where do the genes flow to? a) The genes flow from a locus on one chromosome to a locus on another chromosome. b) The genes flow from a locus on one chromosome to another locus on the same chromosome. c) The genes flow through cyberspace. d) The genes flow into and out of the population due to migration of individuals from one population to another. e) The genes do not flow at all—flow is a mathematical metaphor that means gene frequencies are unstable and are drifting from one number to another.

It is said that the fossil record is an incomplete record, why is that? a) The soft parts of an organism almost always decay rapidly and completely after death. b) Only a few environments demonstrate reduced forces of decomposition resulting in the preservation of the organism's hard parts (i.e., teeth, bones). c) Scientists know the number of fossils embedded in this earth due to radiometric testing, but they have only been able to locate about 10% of them. d) The fossil record is no longer considered to be incomplete. That is an outdated concept that has since been rejected. e) Both the first and second choices best explain this statement.

Which one of the following is NOT an agent of evolutionary change? a) Natural selection b) Mutation c) Genetic drift d) Migration e) Genetic shift

The origin of all genetic variation is: a) mutation. b) respiration. c) glycolosis. d) digestion. e) mitosis.

Convergent evolution can occur only when two species: a) are separated by a barrier such as a new river. b) live in the same geographic area. c) have a recent common ancestor. d) are both inedible to predators. e) evolve under similar selective forces.

Adaptation: a) occurs for physical traits but not behaviors. b) refers both to the process by which organisms become better matched to their environment and to the features of an organism that make it more fit than other individuals. c) cannot occur in environments influenced by humans. d) is responsible for the fact that porcupines are at unusually high risk of predation. e) is possible only when there is no mutation

Which of the following is not a source of evidence demonstrating the occurrence of evolution? a) molecular biology b) comparative anatomy and embryology c) the fossil record d) biogeography e) everything listed is evidence demonstrating the occurrence of evolution.

_____________ selection favors organisms with phenotypes that are at one extreme relative to the average phenotype. a) Stabilizing b) Disruptive c) Directional d) Intense e) Intermittent

Evolution is defined as: a) survival of the fittest. b) a change in the frequency of a physical trait in a population over time. c) a change in the frequency of alleles in a population over time. d) a change in a physical trait of an individual during its lifetime. e) a progressive "ladder" of changes from most primitive organisms to most advanced organisms.

Natural selection can only act on traits: a) that reduce mortality. b) that confer a reproductive advantage. c) that are acquired in an individual's lifetime. d) that are heritable. e) that are adaptive.

Which of the following statements is NOT important to Darwin's theory of natural selection? a) Some variation found in natural populations is heritable. b) Variation is found in all natural populations. c) All species have the ability to produce more offspring than can live and reproduce. d) Offspring tend to inherit characteristics acquired by their parents during their lifetimes. e) None of the above; all are important to his theory.

Many mosquito populations today are resistant to pesticides that were historically effective. This pesticide resistance arose in these populations because: a) individual mosquitoes built up immunity to the pesticides after exposure. b) the pesticides caused mutations in the DNA of mosquitoes that conferred resistance phenotypes, and were passed on to subsequent generations. c) populations had to develop tolerance in order to survive. d) some individuals were resistant to the pesticides before they were used, and those mosquitoes were more likely to survive and reproduce. e) these populations were outside the range of the original pesticide application.

Which of the following is the best measure of an organism's fitness? a) its size, compared to other members of the same species b) the number of fertile offspring it produces c) the amount of care it receives from its parents d) the number of mutations it acquires in its lifetime e) how long it lives

When a sudden change in the environment, such as a flood or a fire, reduces the size of a population, the survivors' collective gene pool becomes only a limited representation of what was present before the disaster. This phenomenon is called: a) the founder effect. b) the Hardy-Weinberg equilibrium. c) the genetic load. d) the bottleneck effect. e) the culling effect.

Artificial selection was used on corn to produce a single strain of corn with increased growth rates and greater resistance to a fungus. Although farmers have continued to select for these traits, the productivity of this strain is no longer increasing. This suggests that: a) gene migration is a major evolutionary agent in corn. b) all or most of the natural variation for these traits has been eliminated. c) the population size has been decreasing. d) artificial selection is not as strong as natural selection. e) long-term disruptive selection may lead to speciation.