Mastering Biology HW 2
Which of these lists contains the four postulates of natural selection?
Variation in population, heritable variation, selection, differential survival or reproduction This list contains all four of the postulates of natural selection.
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. Darwin and Wallace observed similar fact patterns in nature and came to the same explanation about the origin of species.
Which term describes the ability of a trait to be passed on to offspring?
Heritability Heritability is the ability of a trait to be passed on to offspring.
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. This is an accurate statement of the first two steps in the sequence of natural selection.
Which pair of chickens should a farmer breed to produce larger chickens?
Large hen, large rooster Large parents should be bred to produce larger offspring.
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. For Wallace, the unnecessary arm and finger bones in manatee flippers show that they descended from an ancestor with arms. These vestigial structures are evidence that every species is a modified form of an older species.
Which of the following observations led to Darwin's major inferences?
Members of a population vary in their heritable traits. Although organisms can produce huge numbers of offspring, many of these offspring do not survive.
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. Special creation was the prevailing idea of the time. Darwin, like most other scientists, began his journey believing species were unchanging and specially created by God.
Which of the following statements about natural selection is true?
Natural selection favors individuals that reproduce more than others. Individuals who are better able to survive and reproduce are more likely to be selected for than individuals who don't survive or cannot reproduce.
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. A cell's drug susceptibility or resistance does not affect its ability to infect another host, although a cell's drug resistance would increase that cell's chances to spread in an environment containing antibiotics due to increased survival.
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. If all these conditions are true, then the corn borer might evolve resistance to the toxic protein.
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. Bacterial cells have higher fitness when they are drug resistant in the new environment in which people have been medicated with antibiotics.
True or false? In an environment without antibiotics, natural selection between drug-susceptible or drug-resistant phenotypes of Mycobacterium tuberculosis would not occur.
True In an environment without antibiotics, individual cells probably would not differ in their reproductive rates or their survival. Without the application of the drug (antibiotic), it would be very difficult to analyze any differences—one wouldn't even be able to sort the cells!
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 This cross would result in an average corn yield of 189.5 bushels/acre and have a medium-high drought resistance, which is the best you can get for both traits.
Which of the following organisms could be produced by artificial selection?
A cow that produces a large quantity of milk. A cow's ability to produce milk is a heritable trait that can be manipulated by artificial selection.
Which term describes a trait that increases an individual's ability to survive in a particular environment?
Adaptation An adaptation is a trait that increases an individual's ability to survive in a particular environment.
What happened in the soapberry bug population in central Florida when the bugs began to feed on smaller goldenrain tree fruits?
Bugs with shorter beaks had more access to food, allowing them to produce more offspring. Bugs that happened to have short beaks were better able to feed on the small fruits. Their increased access to food allowed them to produce more offspring, which also had small beaks. However, bugs with small beaks did not arise in order to feed on the small fruits. Evolutionary change comes about as the proportion of individuals in the population displaying a particular trait increases from generation to generation. The trait does not change gradually in all members of the population.
What is the meaning of Darwin's expression "descent with modification"?
Descent with modification refers to evolutionary change over time. Darwin used this term to describe change in organisms over time, or evolutionary change.
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. Variation in fitness is required for selection to change the characteristics of a population over time. Remember that selection also requires that the variation in fitness be related to a heritable trait.
Darwin and Wallace independently arrived at the same conclusion that species change over time. Which observations supported their conclusions?
Select all that apply. Bird families clustered geographically: cockatoos in the Malay Archipelago and Australia, macaws and hummingbirds in the Americas. Mockingbirds from different Galapagos islands had subtle, consistent differences. The bony shells of armadillos resembled fossilized shells from the extinct Glyptodon. Birdwing butterflies were found throughout the Malay archipelago, but species differed slightly from island to island. Tortoises from different Galapagos islands have distinct shells. The fossilized remains of giant sloths were similar to the smaller, living sloths Darwin encountered. The resemblance between species and the variations among distant species led both Darwin and Wallace to conclude that species change over time.
Soapberry bugs use needlelike "beaks" to feed on seeds within the fruits of various plants. Bugs feed most successfully when their beak length matches the size of the fruit on which they are feeding. For 25 years, populations of soapberry bugs in central Florida have been feeding on small goldenrain tree fruits that were introduced to the area, rather than on the larger native balloon vine fruits that serve as food for other soapberry bug populations. Beak lengths of soapberry bugs are variable, but the average beak length is shorter in soapberry bug populations that feed on goldenrain tree fruits than in populations that feed on balloon vine fruits, as shown in the graph. How does natural selection act on beak length in soapberry bug populations?
The action of natural selection on beak length in soapberry bug populations varies with the environment. Traits favored by natural selection may change as the environment in which a population lives changes. Selection and adaptation must always be discussed in the context of a particular environment. Soapberry bugs feed most effectively when their beak length closely matches the size of the seed-containing fruit. In central Florida, where soapberry bugs feed on small goldenrain tree fruits, natural selection has reduced average beak length in the population of bugs. However, in Louisiana, where soapberry bugs feed on larger fruits, natural selection has increased average beak length in the population of bugs.
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. Darwin puzzled over why he found fossils of extinct animals in places where he found similar, living animals. Eventually, these observations supported his idea that today's species descend from older, extinct species.
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. The mottled fish will tend to escape predation because they are camouflaged against the mottled lake bottom. The mottled fish will most likely produce more offspring.
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. Different kinds of animals were restricted to different regions because species come from pre-existing, nearby species. Because the western islands were once all connected, they would have the same species, which are also found in the mainland in Asia. The eastern islands were once also all connects and had the same species, which are also found in Australia.
From his observations of organisms in the Galapagos islands, Darwin reasoned that _____.
organisms had adapted to new environments, giving rise to new species Darwin reasoned that natural selection had increased the match between the organisms and their environment.
