ASTRONOMY 123 Exam III Answers 1. Amino acids and nucleotide bases are the building blocks of d. life. 2. The 1974 message sent from Arecibo consisted of 1679 bits of information. Why was this number of bits chosen? b. 1679 = 23 x 73, two prime numbers. 3. The nucleus of Helium-4 (the most common form of helium) is composed of c. 2 protons and 2 neutrons. 4. The existence of the cosmic microwave background implies b. the universe had a hot, dense period in the past. 5. The charge of an anti-particle is b. opposite to its corresponding particle. 6. Two-way communication with another civilization at a distance of 100 light years will require at least c. 200 years. 7. Regions of the universe now separated by very large distances appeared with the same temperature in the early universe. This is known as d. the horizon problem. 8. Our civilization has sent potential communication into outer space aboard b. the Pioneer and Voyager spacecraft. 9. From a distant stellar system, life on the Earth would be c. very difficult to detect, appearing much like a "biological rust". 10. The Urey-Miller experiment simulated d. the evolution of complex molecules on the primitive Earth. 11. Scientists usually assume life on other planets would be based primarily on the element a. carbon. 12. A "message from the people on Earth" sent in 1974 from the radio telescope Arecibo toward the globular cluster M13 contained the following e. information about life on Earth and the location of Earth. 13. Extrasolar planets have been detected by a. the wobble of the associated star. 14. Two acronyms related to our study of extraterrestrial intelligence are d. CETI and SETI. 15. The best part of the radio spectrum for searching for extraterrestrial intelligence is called a. the "water hole". 16. A technological civilization would probably "announce" itself to the universe through a. radio & television signals. 17. The fusion processes that convert light elements to heavier ones are called a. nucleosynthesis. 18. During the Big Bang, which of the following elements was formed in the largest quantity? a. helium 19. The flatness problem is solved by a. Inflation. 20. Hot dark matter consists of a. light particles such as neutrinos. 21. What is the Murchison meteorite? d. A meteorite found in Australia in 1969, containing large amounts of amino acids and other organic material. 22. The abundance of which of the following elements is an important confirmation of the Big Bang Theory? d. Helium and Deuterium 23. If the early universe differed slightly from the critical density it would now differ greatly. This is known as c. the flatness problem. 24. When the energy of photons was converted to matter and anti-matter in the very early universe. a. Matter and anti-matter were initially created equally. 25. Carbon Chauvinism refers to a. the assumption that extraterrestrial life is based on carbon. 26. The radiation era ended and the matter era began about ________ after the Big Bang started. c. 50,000 years 27. What is an argument given to justify CETI? a. Extraterrestrials could have very advanced knowledge. 28. The theories that unify the forces of nature are a. GUTs. 29. What was Project Phoenix? b. A search for extraterrestrial intelligence on millions of radio frequencies. 30. Two sources of energy for chemical reactions available on the young Earth were a. lightning and volcanism. 31. The fossil record shows existence of life on Earth dating back a. billions of years. 32. The Drake equation estimates the number of _______ in the Milky Way Galaxy. a. technological civilizations 33. Most of the fusion of the nuclear epoch occurred during the first ____________ of the Big Bang. b. 20 minutes 34. Why are scientists generally very skeptical about claims of UFO sightings? a. Many are explained by optical illusions. b. Many turn out to be fraud. c. There has been no sign of attempts for such visitors to contact world leaders. ---> d. All of the above. 35. The spurt of growth in the size of the universe occurred during c. Inflation. 36. The naturally occurring molecules, present in the young Earth, included a. water. b. carbon dioxide. c. methane. d. ammonia. ---> e. all of the above. 37. Inflation occurred within __________ of the Big Bang. a. 10-35 seconds 38. When matter and anti-matter are brought together c. they annihilate to produce energy in the form of electromagnetic radiation. 39. Cold dark matter consists of c. heavy particles. 40. The horizon problem is solved by a. Inflation. 41. The temperature fluctuations on the microwave background are found to be c. a few parts per 100,000. 42. The first density fluctuations in the universe probably occurred in a. the dark matter. 43. Dark matter is thought to make up about ___ percent of all matter in the universe. d. 80 44. When matter first appeared in the universe, it was produced along with b. anti-matter. 45. The best wavelength of the electromagnetic spectrum for searching for extraterrestrial intelligence is c. near the 21-cm line of hydrogen. 46. Which of the following is not part of the Drake equation? b. Rate of molecular evaporation. 47. Pair production can create which of the following pairs c. an electron and a positron. 48. What evidence do we have that we have entered the dark energy era? c. The expansion of the universe appears to be accelerating. 49. The universe expanded by a factor of about 1050 during b. inflation. 50. The fluctuations in the microwave background were discovered by a. COBE. 51. The search for extrasolar planets is biased toward c. large planets orbiting close to a star. 52. The present-day universe is composed of a. much more matter than anti-matter. 53. The very early universe was c. radiation dominated. 54. The present day universe is now thought to be d. dark energy dominated. 55. So far the search for technological extraterrestrial intelligence has revealed a. a dozen planets with some early intelligence. b. six planets with some early intelligence. c. just two candidate planets with signs of intelligence. ---> d. none of the above. 56. Which of the following is NOT true of the concept of cosmic inflation? c. Inflation solves the Collider Problem 57. What era was the universe in during galaxy formation? a. Matter era 58. Cosmological models predict there should be tiny _____ on the cosmic microwave background c. "ripples" 59. All of the hydrogen of the universe and most of the helium observed today were created by b. primordial nucleosynthesis. 60. Which of the following is favored as the dominant form of matter in the universe? d. Cold dark matter 61. An alternative to carbon-based life seriously considered by astrobiologists but generally considered unlikely is d. silicon-based life. 62. In considering alternatives to carbon-based life, astrobiologists look for b. a chemical basis which forms large molecules. 63. What important molecules were found in the first Urey–Miller experiment? e. amino acids 64. What satellite has discovered the most extrasolar planets? a. Kepler 65. How many extrasolar planets have been confirmed? d. more than 1000 66. When did life first appear on Earth? d. about 3.5 billion years ago 67. In searching for evidence of extraterrestrial life, scientists look for lifeforms which include all the following, except a. react to environment and heal ---> b. form social interactions c. grow by producing energy from food d. reproduce and pass along traits e. evolve from generation to generation and adapt 68. Biological material represents what fraction of the mass of the Earth? e. less than 1/1,000,000,000 or less than 10-9 69. Which of the following expressions most closely resembles the Drake Equation? d. N = R* fp ne fe fi fc L 70. Occam's Razor says among competing hypotheses, the best is d. the simplest that satisfies all the evidence.