Chapter 19 Practice

Chapter 19

Student: ______

1. Some viruses never use DNA to carry out protein synthesis and have only RNA as their genetic material. This would lend evidence to which theory? A. RNA-first hypothesis B. Protein-first hypothesis C. Simultaneous evolution of RNA and proteins

2. Which of the following time periods contains the others? A. Cretaceous B. Triassic C. Jurassic D. Mesozoic

3. The first known multicellular organisms evolved how many years ago? A. 3.5 BYA B. 2.1 BYA C. 1.4 BYA D. 100 MYA

4. Recall the photographs from the U.S. moonwalks. Not only did the astronauts have to supply their own tanks to maintain a breathing atmosphere and body pressure, the color of the "sky" above the horizon was black. What is/are the primary reason(s) that the moon has no atmosphere? A. There were absolutely no atoms of carbon, oxygen, or nitrogen in the primordial mass that became the moon. B. Because it moves closer to the sun half the time, the atmosphere boiled away. C. The smaller size provided too little gravitational force to hold an atmosphere. D. Sunlight was critical, and the moon receives far less sunlight per unit area than the earth. E. All of the choices are correct.

5. Which of the following kinds of molecules is thought to have been absent from the primitive reducing atmosphere? A. water vapor (H2O) B. carbon dioxide (CO2) C. hydrogen (H2) D. oxygen (O2) E. nitrogen (N2)

6. Which of the following forms of energy is NOT one of those thought to have been involved in the production of large organic molecules in the primitive reducing atmosphere? A. radioactivity B. electrical energy C. heat D. radiation from the sun E. sound

7. The term "reducing atmosphere" for the early earth means that the atmosphere A. was much thinner around the surface of the earth than now. B. contained only two or three kinds of gases. C. contained little or no free oxygen. D. contained little or no free nitrogen. E. contained little or no carbon dioxide.

8. The first person who proposed that small organic molecules could have arisen by chemical evolution was A. Stanley Miller. B. Graham Cairns-Smith. C. Thomas Cech. D. Aleksander Oparin. E. Sidney Fox.

9. The person who performed an experiment that proved that amino acids could be produced in the laboratory from a reducing atmosphere and electrical sparks was A. Stanley Miller. B. Graham Cairns-Smith. C. Thomas Cech. D. Aleksander Oparin. E. Sidney Fox.

10. The hypothesis that suggests that clay may have served as the site of polymerization of both nucleic acids and proteins that might have joined to form the first protocells was proposed by A. Stanley Miller. B. Graham Cairns-Smith. C. Thomas Cech. D. Aleksander Oparin. E. Sidney Fox.

11. The Greek terms for "small" and "ball" are the root words for A. proteinoid. B. polymer. C. microsphere. D. coacervate. E. liposome.

12. Which statement is NOT true about the RNA-first hypothesis? A. It is supported by the discovery that RNA can act as a catalyst. B. It is supported by the fact that some viruses have RNA as their genetic material. C. It suggests that there was an "RNA world" about 4 billion years ago. D. It says that first RNA, then DNA, then proteins would have been necessary to interact in the chemical evolution that would have led to the development of the first cells.

13. If the hypothesis that protocells were based on an "RNA world" is correct, what would be necessary to shift to a "DNA world"? A. an enzyme or reaction capable of removing one oxygen from ribose in nucleotides B. enzymes for reverse transcription of RNA into DNA C. new enzymes to replicate the DNA D. new enzymes for transcribing DNA back to RNA E. All would be necessary to switch to a "DNA world."

14. The fact that a nucleic acid is a very complicated molecule suggests that A. the RNA-first hypothesis is impossible. B. the protein-first hypothesis is therefore the only plausible hypothesis. C. sophisticated enzymes were not present or available to synthesize it. D. no natural system could ever generate it. E. RNA could not have arisen on its own by chance, but required enzymes to guide the synthesis of nucleotides and nucleic acids.

15. The Greek terms for "fat" and "body" are the root words for A. proteinoid. B. polymer. C. microsphere. D. coacervate. E. liposome.

16. Biology books earlier in this century assumed that the earliest protocells would have to be autotrophs. This concept appears to be A. correct, since heterotrophs would depend upon eating autotrophs. B. correct, since life is not possible without ATP, which is only available in living systems. C. correct, since glycolysis and fermentation only occur after oxygen is present from photosynthesis. D. incorrect, since the primordial soup could contain many preformed food molecules. E. incorrect, since glycolysis and fermentation require complex enzymes for catalytic reactions.

17. Which of these would have been most likely to develop only after the formation of a true cell? A. autotroph B. heterotroph C. protocell D. microsphere E. proteinoid

18. Which statement is NOT true about a protocell? A. It would have contained DNA as its genetic material. B. It would have been present before the development of a true cell. C. It would have had a lipid and protein membrane surrounding it. D. It would have contained a biochemical pathway for energy metabolism. E. It might have been like a coacervate droplet in which a semipermeable boundary allows some materials to be absorbed from the surrounding environment.

19. The Greek terms for "different" and "food" are the root words for A. autotroph. B. heterotroph. C. microsphere. D. coacervate. E. liposome.

20. Because of its widespread use in all living organisms, ______is thought to have been one of the earliest metabolic pathways developed by life. A. glycolysis B. fermentation C. the Krebs cycle D. photosynthesis

21. Biological evolution differs from chemical evolution in that it would have been possible only after the development of A. true cells. B. nucleic acids. C. enzymes. D. a metabolic pathway.

22. The molecule needed to allow a cell to transfer genetic information from RNA to DNA is A. DNA polymerase. B. RNA polymerase. C. reverse transcriptase. D. chlorophyll.

23. The synthesis of DNA or RNA from the organic soup would have been guided by the actions of enzymes in the A. protein-first hypothesis. B. RNA-first hypothesis. C. clay-catalyst hypothesis. D. chloroplast.

24. The dilemma of whether proteins or nucleic acids directed the first synthesis of the other is avoided by the A. protein-first hypothesis. B. RNA-first hypothesis. C. clay-catalyst hypothesis.

25. The Latin term for "dug up" is the root word for A. protocell. B. polymer. C. microsphere. D. paleontology. E. fossil.

26. The modern term derived from the Greek root words meaning "ancient," "having existed," and "study of" is A. anthropology. B. biogeography. C. museology. D. paleontology. E. sedimentology.

27. Prokaryotic cells are represented by fossils that are dated back as far as _____ billion years ago. A. 1.5 B. 2.8 C. 3.8 D. 4.8

28. The oxidizing atmosphere probably developed about _____ billion years ago. A. 1.5 B. 2.5 C. 3.5 D. 4.5

29. The first autotrophs probably were _____ and produced ______. A. photosynthetic, oxygen. B. photosynthetic, no oxygen. C. eukaryotic, oxygen. D. eukaryotic, no oxygen. 30. The first eukaryotic cells probably arose about _____ billion years ago. A. 2.1 B. 2.5 C. 3.5 D. 4.5

31. Which pairing of occurrence and date is NOT correct? A. origin of multicellular organisms—650 million years ago B. origin of life—4.8 billion years ago C. origin of eukaryotic cells—2.1 billion years ago D. All the choices are incorrect.

32. Which of the following is correct regarding the dating of fossils with radioisotope decay? A. Decay is uniform, and there is no limit to the measurement technique aside from the quantity of sample taken. B. There is always an upper limit to how far back the decay can be measured, and the closer to the present, the more accurate we can be. C. There is always a lower limit to how far back the decay can be measured, and the further from the present, the more accurate we can be. D. For short-life isotopes, there is an upper limit when the amount of radioactive isotope is too small to measure; with long-life isotopes, there is a limit on how near the recent they are since too little decay has occurred. E. For long-life isotopes, there is an upper limit when the amount of radioactive isotope is too small to measure; with short-life isotopes, there is a limit on how near the recent they are since too little decay has occurred.

33. The Greek term for "molten" or "able to flow" is the root word for A. subduction. B. transform. C. tectonics. D. sedimentation. E. fossil.

34. Africa, Asia, South America, and Antarctica share some patterns of primitive (fossil) plants and early reptiles, but do not have similar mammal populations. This, therefore, A. casts serious doubts upon the theory of continental drift and fused land masses. B. is an unsolved puzzle probably due to the random nature of biological evolution. C. suggests that a pattern of land bridges existed at different times in geological history. D. suggests that the earlier plants and reptiles evolved while continents were joined, but mammals radiated into diverse groups after separation. E. suggests that the mammals evolved earlier while continents were joined, but plants and reptiles radiated into diverse groups after separation.

35. Consider that the rock outcrops at the surface of the land in your neighborhood are Permian. What would be true if you dig downward? A. You may find dinosaur fossils below. B. You may find fossils of first flowers. C. All five of the other Paleozoic layers will be present underneath. D. A roadcut in your area would reveal exactly the same species of fossils as a roadcut through a Permian layer in Asia. E. None of the choices is true. 36. The primitive Earth's atmosphere contained gases produced by A. outgassing by the Earth's interior. B. gravitational energy. C. radioactivity. D. All of the choices are true.

37. In the evolution of the first cells on the developing planet Earth, polymers had to evolve. The following support this path toward cell development EXCEPT for A. amino acid exposure to amino acids were shown to abiotically polymerize by Fox B. clay was helpful in the polymerization of proteins and nucleic acids as shown by Cairns-Smith C. Chech and Altman's RNA first hypothesis D. adaptive radiation

38. In the history of life development on Earth one must A. trace events that compose macroevolution. B. examine the fossil record. C. examine biogeographical evidence. D. all of the choices must be considered.

39. In the geological time scale, which of the following eras is miss-matched with the organisms? A. Precambrian -- protists evolve B. Mesozoic -- appearance and spread of flowering plants C. Paleozoic -- forests of cycads D. Cenozoic -- humans

40. The appearance of photosynthetic cyanobacteria and aerobic bacteria A. led to the development of an oxidizing atmosphere on Earth. B. led to the formation of the ozone shield. C. The amount of UV light reaching the Earth was reduced and chemical evolution slowed. D. All of the choices are correct.

41. The theory of continental drift indicates all of the following EXCEPT A. explains why the coastlines of several continents mirrors those of each other B. shows why the same geological structures are also found in areas where the continents touched C. continental drift has ceased D. why the unique patterns of fossils occur in the fossil record.

42. Mass extinctions A. have occurred at least 5 times throughout Earth's history. B. may have been due to climatic changes after a metorite collision. C. may have followed continental drift. D. All of the choices are correct.

43. Human evolution began with the first hominids during the Jurassic period. True False

44. Organisms today are living in the Pleistocene epoch of the Cenozoic era. True False

45. The term "organic soup" refers to the ancient oceans before life formed, in which organic molecules such as amino acids accumulated. True False 46. Microspheres are structures made up of lipid and protein membranes with many of the properties of a cell, such as metabolic pathways. True False

47. A ribozyme is a molecule of RNA that has catalytic properties. True False

48. Natural selection would have selected for those protocells and cells that were more able to use the energy available in their environment to allow growth and replication. True False

49. The protein-first hypothesis is based on the research of Thomas Cech and Sidney Altman, who found that protein can act as both a substrate and an enzyme. True False

50. The central dogma of genetics probably developed as a series of steps through evolution, so that the flow of information now generally proceeds DNA —> RNA —> protein. True False

51. The earliest known fossils, stromatolites, are communities of microorganisms that have been extinct for over 2 billion years. True False

52. Organisms first became able to live on the land after the development of the ozone layer, because it protected them from the harmful effects of sunlight. True False

53. Multicellular organisms probably arose first about 1 billion years ago, resulting in a burst of diversification of organisms and their movement onto land. True False

54. That the ancient Earth's atmosphere lacked oxygen was beneficial because oxygen combines with organic molecules to prevent them from forming polymers. True False

55. The event that initiated biological evolution was the flow of information from DNA to RNA to protein. True False

56. Wegener first presented the idea of continental drift in 1920 and this theory was confirmed in 1960. True False

57. Why would the earliest cells most likely have been heterotrophs, and why would autotrophs have developed later?

58. Why is a reducing atmosphere more likely to allow the buildup of organic molecules from small inorganic molecules than is an oxidizing atmosphere?

59. Explain why the development of an oxidizing atmosphere would have been dependent on living organisms, and how that would have affected the evolution of new species and the availability of habitat sites for life.

60. Describe how eukaryotic cells are thought to have developed, and why their presence would have allowed the development of multicellular organisms.

61. One simple definition of life is a self-replicating molecular assemblage. However, layers of clay mineral form similar templates over time, including copying even the flaws in the layers. Yet these molecular assemblages never go on to exhibit properties of life. (This is not the Cairns-Smith model.) Why does such simple "abiotic" chemistry not have the potential for life that we see in the "prebiotic" chemistry described in this chapter?

62. "Protometabolism" is sometimes the word used for prebiotic synthesis reactions that are only a step or two more complex than the abiotic synthesis demonstrated by Stanley Miller. Why is the evolution of the earliest genuine cell sometimes referred to as a matter of "mastering information"?

63. For a brief time, some people believed that they had discovered fossilized human footprints alongside dinosaur tracks in a creek bed. Further examination revealed that these were the eroded footprints of another dinosaur. If this had proven to be genuine fossil evidence of humans coexisting with dinosaurs, why would this have posed extensive problems for evolutionary biologists and the current understanding of the geological record? While primitive life forms arise early and often continue to exist, there is no evidence of advanced or derived organisms in far earlier strata. Why does this continue to reinforce the theory of evolution?

64. Describe continental drift and how it is important in the evolution of life forms.

65. Once the Alvarez theory on dinosaur extinction gained acceptance, why do we apply it to some but not all of the other major extinctions?

Chapter 19 KEY

1. A 2. D 3. C 4. C 5. D 6. E 7. C 8. D 9. A 10. B 11. C 12. D 13. E 14. E 15. E 16. D 17. A 18. A 19. B 20. A 21. A 22. C 23. A 24. C 25. E 26. D 27. C 28. B 29. B 30. A 31. B 32. D 33. C 34. D 35. E 36. A 37. D 38. D 39. C 40. D 41. C 42. D 43. FALSE 44. FALSE 45. TRUE 46. FALSE 47. TRUE 48. TRUE 49. FALSE 50. TRUE 51. FALSE 52. TRUE 53. FALSE 54. TRUE 55. TRUE 56. TRUE 57. Answers will vary. 58. Answers will vary. 59. Answers will vary. 60. Answers will vary. 61. Answers will vary. 62. Answers will vary. 63. Answers will vary. 64. Answers will vary. 65. Answers will vary.