Guided course 08:13Biogeography, Fossil Record, and Radiocarbon DatingJason Amores Sumpter1547views26rank
13:18Plate tectonics: Evidence of plate movement | Cosmology & Astronomy | Khan AcademyKhan Academy370views
Multiple ChoiceWhy is the four-stage hypothesis for the abiotic origin of life useful? 1164views1rank
Multiple ChoiceThe early atmosphere on Earth is thought to have lacked which of the following gases? 699views
Multiple ChoiceCurrently scientists think the early atmosphere probably consisted of __________. 372views
Multiple ChoiceThe Miller and Urey abiotic synthesis experiment (and subsequent, similar experiments) showed that __________. 479views
Multiple ChoiceThe early atmosphere may not have been as reducing as originally postulated by Haldane, Oparin, Miller, and Urey. In light of current thinking about the composition of the early atmosphere, what is regarded as a likely place for the abiotic synthesis of organic molecules to have occurred? 520views
Multiple ChoiceAbiotically produced vesicles display which of the following rudimentary qualities necessary for life? 486views
Multiple ChoiceMany researchers now believe that the first self-replicating molecules were __________. 555views
Multiple ChoiceA radioactive isotope has a half-life of 1.2 billion years. As measured by the presence of the isotope and its stable decay product, a rock originally contained 10 grams of the radioactive isotope and now contains 1.25 grams. Approximately how many years old is the rock? 738views2rank
Multiple ChoiceYou are watching a movie in which one of the characters excitedly claims to have found human remains in Asia dated at 10 million years old. The date was obtained by carbon-14 dating. What is your reaction? 773views
Multiple ChoiceSingle-celled prokaryotes had Earth to themselves for approximately __________. 511views
Multiple ChoiceThe correct order of the geologic eras, from most ancient to most recent, is __________. 474views
Multiple ChoiceAncient cyanobacteria were very important in the history of life because they __________. 487views
Multiple ChoiceWhat prokaryotic adaptation occurred during the oxygen revolution and opened up the possibility for energy-demanding multicellular life-forms? 479views
Multiple ChoiceWhat evidence supports the hypothesis that mitochondria and plastids evolved from prokaryotic endosymbionts? 1208views
Multiple ChoicePrior to the Cambrian explosion, most animals were small and soft-bodied. What development appears to have spurred adaptations such as sharp spines, claws, and body armor (shells)? 631views
Multiple ChoiceWhat evidence most strongly suggests that an impact by an asteroid or meteorite may have caused the extinction of the dinosaurs? 1399views
Multiple ChoiceWhat were the two major "problems" that had to be solved before plants, animals, and fungi could fully move into terrestrial habitats? 318views
Multiple ChoicePlants colonized land in the company of __________; their symbiotic relationships still exist today. 423views
Multiple ChoiceWhich of the following best describes how the breakup of Pangaea affected evolution? 662views
Multiple ChoiceLake Malawi, in the African Rift Valley, is home to more than a hundred species of cichlid fishes, each with slightly different diets and habits. All these species probably evolved from a common ancestor, making them an example of __________. 470views
Multiple ChoiceThe fauna and flora of Australia are very different from those of the rest of the world. Why might this be true? 515views
Multiple ChoiceAlthough they originated around 180 million years ago, mammals underwent an adaptive radiation starting approximately 65 million years ago. Why? 1232views
Multiple ChoiceMutations in what class of genes have probably been responsible for many of the changes leading to the great diversity of life existing today? 354views
Multiple ChoiceIf the feathers of extant flying birds originally arose as thermoregulatory devices in ancestral reptiles, then flight feathers could be accurately described as __________. 313views
Multiple ChoiceIn the species selection model, __________ is to macroevolution as __________ is to microevolution. 411views
Multiple ChoiceWhich of the listed examples is a current hypothesis regarding the Cambrian explosion? 394views
Textbook QuestionHow many different species have been identified by science? How many are estimated to exist?625views
Textbook QuestionAdd labels to the figure that follows, which illustrates the endosymbiotic hypothesis.387views
Textbook QuestionFill in the blanks in the following graph, which illustrates the decay curve of a radioactive element used to date fossil structures. 334views
Textbook QuestionThe process of biological evolution . a. is not supported by scientific evidence; b. results in a change in the features of individuals in a population; c. takes place over the course of generations; d. B and C are correct; e. A, B, and C are correct661views
Textbook QuestionYou set your time machine for 3 billion years ago and push the start button. When the dust clears, you look out the window. Which of the following describes what you would probably see? a. a cloud of gas and dust in space b. green scum in the water c. land and water sterile and devoid of life d. an endless expanse of red-hot molten rock310views
Textbook QuestionLarge-scale, worldwide adaptive radiations have occurred in which of the following situations? (A)when there are no available ecological niches (B)after each of the big five mass extinctions (C)after colonization of an isolated island that contains suit-able habitat and few competitor species (D)whenever an evolutionary innovation was needed for or-ganisms to thrive845views
Textbook QuestionAdaptive radiations can be a direct consequence of three of the following four factors. Select the exception. a. vacant ecological niches b. genetic drift c. colonization of an isolated region that contains suitable habitat and few competitor species d. evolutionary innovation678views
Textbook QuestionAncient photosynthetic prokaryotes were very important in the history of life because they a. produced the oxygen in the atmosphere. b. are the oldest-known archaea. c. were the first multicellular organisms. d. showed that life could evolve around deep-sea vents.680views
Textbook QuestionScientists studying the origin of life have accomplished which of the following steps? (A)abiotic synthesis of protocells with self-replicating, catalytic RNA (B)formation of vesicles that use RNA as a template for DNA synthesis (C)formation of protocells that use DNA to direct the polymer-ization of amino acids (D)abiotic synthesis of RNA's bases (A, C, G, U)1421views
Textbook QuestionWhich of the following steps has not yet been accomplished by scientists studying the origin of life? a. synthesis of small RNA polymers by ribozymes b. formation of molecular aggregates with selectively permeable membranes c. formation of protocells that use DNA to direct the polymerization of amino acids d. abiotic synthesis of organic molecules541views
Textbook QuestionThe animals and plants of India are very different from the species in nearby Southeast Asia. Why might this be true? a. India was once covered by oceans and Asia was not. b. India is in the process of separating from the rest of Asia. c. Life in India was wiped out by ancient volcanic eruptions. d. India was a separate continent until about 45 million years ago.409views
Textbook QuestionAdaptive radiations may be promoted by all of the following except one. Which one? a. mass extinctions that result in vacant ecological niches b. colonization of an isolated region with few competitors c. a gradual change in climate d. a novel adaptation641views
Textbook QuestionFossilization continues even today. If you wanted to increase the probability that your deceased favorite pet would become fossilized, what actions would you take? a. Place the corpse in an environment where decomposition is rapid (such as a forest). b. Place the corpse in an environment where decomposition is slow (such as a swamp or bog). c. Place the corpse in an environment where there are plenty of rocks (such as a boulder field). d. Place the corpse in an environment where plenty of oxygen is available (such as in a mountain stream).377views
Textbook QuestionIn the late 1700s, machines that could blast through rock to build roads and railways were invented, exposing deep layers of rocks. How would you expect this development to aid the science of paleontology?335views
Textbook QuestionMajor divisions in the geologic record are marked by a. radioactive dating. b. distinct changes in the types of fossilized life. c. regular time intervals measured in millions of years. d. the appearance, in order, of prokaryotes, eukaryotes, protists, animals, plants, and fungi.336views
Textbook QuestionWrite a paragraph briefly describing the kinds of scientific evidence for evolution.308views
Textbook QuestionIn the early 1800s, French naturalist Jean Baptiste Lamarck suggested that the best explanation for the relationship of fossils to current organisms is that life evolves. He proposed that by using or not using its body parts, an individual may change its traits and then pass those changes on to its offspring. He suggested, for instance, that the ancestors of the giraffe had lengthened their necks by stretching higher and higher into the trees to reach leaves. Evaluate Lamarck's hypotheses from the perspective of present-day scientific knowledge.484views
Textbook QuestionSCIENTIFIC THINKING Cetaceans are fully aquatic mammals that evolved from terrestrial ancestors. Gather information about the respiratory system of cetaceans and describe how it illustrates the statement made in that 'Evolution is limited by historical constraints.'341views
Textbook QuestionAdvocates of 'scientific creationism' and 'intelligent design' lobby school districts for such things as a ban on teaching evolution, equal time in science classes to teach alternative versions of the origin and history of life, or disclaimers in textbooks stating that evolution is 'just a theory.' They argue that it is only fair to let students evaluate both evolution and the idea that all species were created by God as the Bible relates or that, because organisms are so complex and well adapted, they must have been created by an intelligent designer. Do you think that alternative views of evolution should be taught in science courses? Why or why not?299views
Textbook QuestionMeasurements indicate that a fossilized skull you unearthed has a carbon-14: carbon-12 ratio about 1/16th that of the skulls of present-day animals. What is the approximate age of the fossil? (The half-life of carbon-14 is 5,730 years.)569views
Textbook QuestionSCIENTIFIC THINKING When Stanley Miller's experiment was published in 1953, his results made global headlines. The general public thought Miller had answered the question of how life on Earth began by creating life in a test tube. However, scientists understood that Miller's experiment was neither a final answer nor a recipe for life. Rather, it was the first test of a long-standing hypothesis about the origin of life. Write an essay describing how the process of science progresses over time toward understanding how nature works.626views