Life in the Universe Full Test Bank Chapter.18

Chapter 18: Life in the Universe

LEARNING OBJECTIVES

18.1 Life on Earth Began Early and Evolved Over Time

18.1a Describe life.

18.1b Compare and contrast the three major theories presented in this text of how life originated on Earth.

18.1c Explain why the earliest forms of life on Earth must have been extremophiles.

18.1d Describe the timeline for the rise and extinction of the dinosaurs.

18.1e Establish why mutation and heredity lead to evolution.

18.1f Describe the process of natural selection.

18.1g Summarize the evolution of life from its first origins on Earth until today.

18.2 Life beyond Earth Is Possible

18.2a Explain why carbon is favored as, but is not the only, chemical basis of life.

18.2b Assess whether we expect to find life outside of Earth.

18.2c Describe how the habitable zone changes for stars of different masses.

18.2d Describe a galactic habitable zone.

18.3 Scientists Search for Signs of Intelligent Life

18.3a Summarize the current state of our attempts to find life beyond Earth.

18.3b Assess why it is unlikely that we will communicate with extraterrestrial beings.

18.4 The Fate of Life on Earth

18.4a Explain why life on Earth is ultimately doomed.

Working It Out 18.1

Working It Out 18.1a Compute how a population changes with time based on exponential growth.

Chapter 18: Life in the Universe

MULTIPLE CHOICE

1. In 1952, chemists Harold Urey and Stanley Miller mixed ammonia, methane, and hydrogen in a closed container, zapped it with electrical sparks, and found that

a. they could induce cold fusion to occur.

b. they could not induce any amino acids to form.

c. single-celled microorganisms had been spontaneously created.

d. they had created about half the amino acids that form proteins.

2. What was produced in the experiment depicted here?

a. helium from hydrogen c. single-celled microorganisms

b. amino acids d. RNA

3. Where do we think life first formed on Earth?

a. in the air

b. in the oceans

c. on land

d. on asteroids that carried microorganisms to Earth

4. Complex microorganisms that have complex DNA enclosed in a cell nucleus are called

a. algae. c. eukaryotes.

b. bacteria. d. prokaryotes.

5. What is true about the seeding hypothesis for the origins of life on Earth?

a. Microbes were brought by comets.

b. Microbes were brought by meteorites.

c. There is no current evidence to support it.

d. All choices are valid.

6. What is the problem with the seeding hypothesis for the origins of life on Earth?

a. The delivery mechanisms are not feasible.

b. There is no evidence of the seed carriers.

c. It does not explain life’s origin elsewhere in the Solar System or beyond.

d. There are no problems; it likely occurred.

7. Where might life have first formed according to the major theories?

a. tidal pools c. elsewhere in the Solar System or beyond

b. ocean depths d. All are valid choices.

8. In which environment did lightning and ultraviole tradiation provide the energy needed to create the highly organized molecules to form life on Earth?

a. tidal pools c. elsewhere in the Solar System or beyond

b. ocean depths d. All are valid choices.

9. In which environment did volcanic vents provide the hydrothermal energy needed to create the highly organized molecules to form life on Earth?

a. tidal pools c. elsewhere in the Solar System or beyond

b. ocean depths d. All are valid choices.

10. What is true about the molecular model depicted here?

a. It is a model of a DNA molecule. c. The shape is known as a double helix.

b. It is the molecular basis for heredity. d. All choices are valid.

11. What occurred approximately 500 million years ago?

a. extinction of the dinosaurs c. rise of mammals

b. Cambrian explosion d. birth of the first humans

12. The phylogenetic tree of life was established using

a. bacteria. c. fossils.

b. DNA sequencing. d. fungi.

13. All terrestrial life is __________ based.

a. carbon c. nitrogen

b. hydrogen d. oxygen

14. Which of the following appeared most recently in Earth’s evolutionary timeline?

a. dinosaurs c. humans

b. forests d. insects

15. If we model the history of Earth as a single day, at what time would the first primitive forms of microorganisms appear?

a. 5:00 A.M. c. 12:00 noon

b. 9:00 A.M. d. 3:00 P.M.

16. If we model the history of Earth as a single day, at what time would the first human civilizations appear?

a. 0.2 seconds before midnight c. 10:00 P.M.

b. 2 minutes before midnight d. 6:00 P.M.

17. Humans belong to which branch of the phylogenetic tree of life?

a. Archaea c. Eukarya

b. bacteria d. fungi

18. Terrestrial life is carbon based and requires __________ as its solvent.

a. carbon c. hydrogen

b. DNA d. liquid water

19. The early Earth suffered a long period of bombardment. With respect to this period, when did life arise and evolve?

a. after bombardment c. during bombardment

b. before bombardment d. We have no way of determining this.

20. Venus and Mars have little free oxygen in their atmospheres. What has allowed Earth to have a large amount of oxygen in its atmosphere?

a. bombardment

b. cyanobacteria and other photosynthesizing organisms

c. volcanism

d. water on Earth’s surface

21. If we model the age of the universe as a single day, at what time would the earliest traces of humanity appear on Earth?

a. 11:00:00 P.M. c. 11:53:10 P.M.

b. 11:35:00 P.M. d. 11:59:25 P.M.

22. When did the extinction of the dinosaurs occur?

a. 10,000 years ago c. 65 million years ago

b. 1 million years ago d. 230 million years ago

23. What event lead to the extinction of the dinosaurs?

a. an asteroid or comet impact c. extreme solar activity

b. a nearby supernova event d. the evolution of humans

24. What directly caused the extinction of 70% percent of all plant and animal life, including the dinosaurs?

a. massive volcanic activity

b. a nearby supernova event

c. extreme solar activity

d. material in the atmosphere dimming the sun for months

25. When did the age of the dinosaurs begin?

a. 10,000 years ago c. 65 million years ago

b. 1 million years ago d. 230 million years ago

26. Fossils such as the one shown here establish that dinosaurs roamed North America about

a. 7,500 years ago. c. 75 million years ago.

b. 7.5 million years ago. d. 7.5 billion years ago.

27. What does it mean if a population demonstrates exponential growth?

a. Population decreases to zero.

b. Population increases by a fixed amount in each given time interval.

c. Population increases by a percentage in each given time interval.

d. There is no such thing as exponential growth.

28. Which of the following is the study of the origin, evolution, distribution, and future of life in the universe?

a. astrobiology c. cosmology

b. biology d. physiology

29. Life in the universe could form

a. after the Big Bang. c. during the Big Bang.

b. before the Big Bang. d. We have no way of determining this.

30. NASA spacecraft have found good evidence that liquid water in large amounts previously existed on the surface of

a. Mars. c. Titan.

b. Mercury. d. Venus.

31. Evidence for lakes of hydrocarbons, such as methane, has been discovered on

a. Mars. c. Titan.

b. Mercury. d. Venus.

32. The habitable zone around a main-sequence star depends most on its

a. mass and age. c. color and distance.

b. radius and distance. d. luminosity and velocity.

33. Why is a very hot star not a good candidate on which to find life?

a. The star is too hot.

b. Hot stars are only found in the disk of the galaxy, which is not conducive to life.

c. Its lifetime is too short for life to evolve.

d. The elements that are around hot stars do not lead to evolution.

34. Why is a cold star not a good candidate on which to find life?

a. The star is too cold.

b. The habitable zone is very narrow.

c. Its lifetime is too long for life to evolve.

d. The elements that are around cold stars do not lead to evolution.

35. Although habitable zones can exist around any star, why do astronomers focus mostly on F, K, G, and M types?

a. Their temperatures are just right.

b. Their habitable zones are wide.

c. Their lifetimes are long enough for life to evolve.

d. They have the right chemical composition.

36. Examine the following image. A habitable zone would roughly be at what distance from a red dwarf star?

a. 0.10 astronomical units (AU) c. 1.00 AU

b. 0.25 AU d. 1.50 AU

37. Which of the following elements is so similar to carbon’s structure that scientists think it may form a basis for life elsewhere?

a. helium c. oxygen

b. nitrogen d. silicon

38. Why does a planet’s size matter when predicting if it can support life?

a. Gravity will determine if a planet can retain an atmosphere.

b. Large worlds are most likely to have life based on our own Solar System.

c. Only very large worlds have atmospheres.

d. Water only exists on very large planets.

39. Carbon forms the backbone of our DNA because

a. it is the most abundant element in the universe after hydrogen and helium.

b. it reacts easily with oxygen.

c. it remains solid even at high temperatures.

d. a carbon atom can bond with up to four atoms at a time.

40. Based on what you know of Earth’s evolution, what percentage of Earth-like planets in a star cluster with an age of 2 billion years has intelligent life?

a. 0 percent c. 30 percent

b. 10 percent d. 50 percent

41. We search for intelligent life in the universe by

a. sending out spacecraft with messages on them.

b. using radio telescopes to search for radio signals.

c. monitoring ultraviolet radiation emitted by stars.

d. all of the above

42. SETI’s Allen Telescope Array is designed to search __________ for signs of intelligent life.

a. more than a thousand stars c. galaxies in the Local Group

b. more than a million stars d. the 100 closest spiral galaxies

43. In 1974, astronomers sent a message toward globular cluster M13. If life exists there, and it returns our signal, why will it take about 50,000 years to receive?

a. It will take that long for the space probe carrying our signal to reach the life forms there.

b. Based on the age of the stars in M13, we anticipate it would take that long for a civilization to evolve enough to interpret and respond to our signal.

c. M13 is far enough away that even light takes a very long time to reach it, be interpreted by an intelligent species, and return it to Earth.

d. It will take that long before our Solar System and M13 are properly aligned again.

44. Why is it unlikely that we will ever contact extraterrestrial life? Choose the most correct answer.

a. Aliens have already contacted us.

b. Life is unlikely to exist elsewhere in the universe.

c. Our technology does not allow us to pick up signals.

d. Space is very big.

45. What is the goal of SETI?

a. to communicate with alien life c. to discover extraterrestrial civilizations

b. to discover alien life of any form d. to protect Earth from aliens

46. A value of N 0.1 for the Drake equation signifies on average that 1 of every 10

a. solar systems in our galaxy harbors intelligent life.

b. solar systems in our galaxy harbors life of some kind.

c. galaxies in our universe harbors intelligent life.

d. galaxies in our universe harbors life of some kind.

47. The Drake equation is used to predict the number of

a. civilizations in the Milky Way Galaxy.

b. Earth-like planets in the Milky Way Galaxy.

c. planets in the Milky Way Galaxy.

d. planets with life in the Milky Way Galaxy.

48. If the most pessimistic assumptions in the Drake equation were true, we would

a. have to wait for approximately 60 million years to get a message back from the nearest intelligent life.

b. have to wait for approximately 400 years to get a message back from the nearest intelligent life.

c. be the only intelligent life in the universe.

d. need to concentrate on the Andromeda Galaxy when searching for intelligent life.

49. All of the following events will likely occur in the future. Which would require that humanity leaves the Solar System to survive?

a. asteroid or cometary impact on Earth

b. continuation of global climate change on Earth

c. evolution of the Sun into a red giant

d. overuse of natural resources on Earth

50. As the Sun evolves into a red giant, what will happen to the location of the habitable zone in our Solar System?

a. move away from the Sun c. remain in its current position

b. move closer to the Sun d. We have no way of predicting.

51. As the Sun evolves into a red giant, where will we need to move to within our Solar System if humanity still exists?

a. Mars c. our Moon

b. Mercury d. the moons of the outer planets

1. Describe the experiments of Harold Urey and Stanley Miller in understanding the origins of life.

2. Describe the difference between prokaryotes and eukaryotes.

3. Make an argument in support of the following statement: “The earliest forms of life on Earth must have been extremophiles.”

4. What other harsh conditions can extremophiles tolerate besides extreme temperatures?

5. Scientists have shown that ammonia and methane, mixed together with hydrogen, carbon dioxide, or nitrogen, can produce some of the amino acids essential for life. What else is necessary in this process and why?

6. What determines whether or not a specific mutation is passed on to future generations?

7. If the entire history of Earth were scaled to fit into 1 day, what time of day would microorganisms first form, oxygen start becoming a significant component of the atmosphere, and humans split off from their genetic ancestors?

8. Explain the roles of mutations and heredity in biological evolution.

9. What are the four main atoms that make up all living organisms on Earth?

10. Describe what is meant by “galactic habitable zone.”

11. If you wanted to find intelligent life in the universe, what spectral types of stars would you study and why?

12. Explain why an exoplanet in a habitable zone around a low-mass star would be more likely to have intelligent life than one similarly placed around a more massive star?

13. Indicate the areas above and below the Earth in the following image for the expected habitable zones given the different stars.

14. Examine the following image. Which star or stars would likely prevent intelligent life from forming and why?

15. Examine the following image. Where outside the habitable zone might life exist in our Solar System and why?

16. Calculate the maximum likelihood that any technically advanced civilization that arose still exists in our galaxy today.

17. Given the following information, what would be the number of intelligent civilizations in our galaxy? If all stars formed planets; each planet has an 0.1 percent chance of developing life; every time conditions are right, life develops; and only 0.001 percent of the time, intelligent life develops surviving indefinitely.

18. Why would the 21-cm line be a good place to search for signals from intelligent life in the universe?

19. What is the SETI@home project?

20. List three most likely reasons why we have not yet detected signals from intelligent life beyond Earth.

21. What is SETI, what is its main objective, and how does it plan to achieve its objective?

22. Name three main dangers (one human and two astrophysical) that threaten the continued existence of human life on Earth.