Chapter 23

According to the theory of sea-floor spreading, oceanic islands, such as the Hawaiian Islands depicted in the figure, form as oceanic crustal plates move over a stationary "hot spot" in the mantle. Currently, the big island of Hawaii is thought to be over a hot spot, which is why it is the only one of the seven islands that has active volcanoes. What should be true of the island of Hawaii? 1. Scientists in search of ongoing speciation events are more likely to find them here than on the other six islands. 2. Its species should be more closely related to those of nearer islands than to those of farther islands. 3. It should have a rich fossil record of terrestrial organisms. 4. There is a good chance of finding endemic species on this island. 5. On average, it should have fewer species per unit surface area than the other six islands.

1, 2, 4, and 5

The first terrestrial organisms probably were considered which of the following? 1. burrowers 2. photosynthetic 3. multicellular 4. prokaryotes 5. eukaryotes 6. plants and their associated fungi

2 and 4

The following question refer to the paragraph below. A sediment core is removed from the floor of an inland sea. The sea has been in existence, off and on, throughout the entire time that terrestrial life has existed. Researchers wish to locate and study the terrestrial organisms fossilized in this core. The core is illustrated as a vertical column, with the top of the column representing the most recent strata and the bottom representing the time when land was first colonized by life. Assuming the existence of fossilized markers for each of the following chemicals, what is the sequence in which they should be found in this sediment core, working from ancient sediments to recent sediments? 1. chitin coupled with protein 2. chlorophyll 3. bone 4. cellulose

2, 4, 1, 3

If the half-life of carbon-14 is about 5,730 years, then a fossil that has one-sixteenth the normal proportion of carbon-14 to carbon-12 should be about how many years old?

22,900

The following question refer to the description and the figure. the figure represents a cross section of the sea floor through a mid-ocean rift valley, with alternating patches of black and white indicating sea floor with reversed magnetic polarities. At the arrow labeled "I" (the rift valley), the igneous rock of the sea floor is so young that it can be accurately dated using carbon-14 dating. At the arrow labeled "III," however, the igneous rock is about 1 million years old, and potassium-40 dating is typically used to date such rocks. Note: The horizontal arrows indicate the direction of sea-floor spreading, away from the rift valley. How many other bands of sea-floor crust in the figure have the same magnetic polarity as the crust that directly straddles the rift valley?

4 bands

The following question refer to the description and the figure. the figure represents a cross section of the sea floor through a mid-ocean rift valley, with alternating patches of black and white indicating sea floor with reversed magnetic polarities. At the arrow labeled "I" (the rift valley), the igneous rock of the sea floor is so young that it can be accurately dated using carbon-14 dating. At the arrow labeled "III," however, the igneous rock is about 1 million years old, and potassium-40 dating is typically used to date such rocks. Note: The horizontal arrows indicate the direction of sea-floor spreading, away from the rift valley. Assuming that the rate of sea-floor spreading was constant during the 1-million-year period depicted in the figure, what should be the approximate age of marine fossils found in undisturbed sedimentary rock immediately overlying the igneous rock at the arrow labeled "II"?

500,000 years

The evolution of mammals from early tetrapods

All of the above statements are true.

The following question refer to the description and the figure. the figure represents a cross section of the sea floor through a mid-ocean rift valley, with alternating patches of black and white indicating sea floor with reversed magnetic polarities. At the arrow labeled "I" (the rift valley), the igneous rock of the sea floor is so young that it can be accurately dated using carbon-14 dating. At the arrow labeled "III," however, the igneous rock is about 1 million years old, and potassium-40 dating is typically used to date such rocks. Note: The horizontal arrows indicate the direction of sea-floor spreading, away from the rift valley. If a particular marine organism is fossilized in the sediments immediately overlying the igneous rock at the arrow labeled "II," at which other location(s), labeled A-E, would a search be most likely to find more fossils of this organism?

C only

What is true of the fossil record of mammalian origins?

It includes transitional forms with progressively specialized teeth.

Upon being formed, oceanic islands, such as the Hawaiian Islands, should feature what characteristic, leading to which phenomenon?

a variety of empty ecological niches, leading to adaptive radiation

Hawaii is the most southeastern of the seven islands and is also closest to the sea-floor spreading center from which the Pacific plate originates, which lies about 5,600 km further to the southeast. Assuming equal sedimentation rates, what should be the location of the thickest sediment layer and, thus, the area with the greatest diversity of fossils above the oceanic crust?

around the base of Kauai, the oldest of the Hawaiian islands

The existence of evolutionary trends, such as increasing body sizes among horse species, is evidence that

in particular environments, similar adaptations can be beneficial in more than one species.

In the 5 to 7 million years that the hominid lineage has been diverging from its common ancestor with the great apes, dozens of hominid species have arisen, often with several species coexisting in time and space. As recently as 30,000 years ago, Homo sapiens coexisted with Homo neanderthalensis. Both species had large brains and advanced intellects. The fact that these traits were common to both species is most easily explained by which of the following?

species selection

Many species of snakes lay eggs. However, in the forests of northern Minnesota where growing seasons are short, only live-bearing snake species are present. This trend toward species that perform live birth in a particular environment is an example of

species selection.

Fossil evidence indicates that several kinds of flightless dinosaurs possessed feathers. If some of these feather-bearing dinosaurs incubated clutches of eggs in carefully constructed nests, this might be evidence supporting the claim that

their feathers originally served as insulation, and only later became flight surfaces.