Astronomy_103_Exam_2_practice_fall2023

ASTRONOMY 103 EXAM 1 – VERSION A Name (Print): Practice exam PID: Honor Pledge: On my honor, I have neither given nor received unauthorized aid on this examination. Signature: Do not open the exam until told to do so. You will have 75 minutes to complete the examination. NO CELL PHONES, INTERNET, TEXT MSG, etc. ALLOWED AT ANY TIME. Before the exam begins: • Print and sign your name, and write your student PID number in the spaces above and on the bubble sheet. During the exam • Mark your answers by filling in the appropriate bubble on the bubble sheet. Only fill in one bubble for each question. • If you are confused by a question, raise your hand. A proctor will try to clarify without giving away the answer. If you are still stuck, move on to the next question and come back to the one that is confusing you later. • You may write on your exam book. However, none of this work will be graded. Only the bubble sheet will be graded. • The last page of the exam has some equations and constants. You are welcome to rip off this last page during the exam. ASTR 103 Practice

Name: Do NOT write outside the box Astronomy 103, Exam 3 – Version A 2 Answer key for Fall 2023 practice exam: 1 d 2 e 3 d 4 e 5 a 6 b 7 d 8 c 9 b 10 e 11 a 12 c 13 a 14 b 15 b 16 e 17 d 18 a 19 a 20 d 21 c 22 a 23 b 24 e 25 c 26 c 27 c 28 d 29 b 30 e 31 b 32 c 33 b 34 b 35 a

Name: Do NOT write outside the box Astronomy 103, Exam 3 – Version A 3 1. Photosynthetic organisms first evolved on Earth around 2 Gyr ago. Which of the following events happened as a result of the appearance of these organisms? a. The amount of carbon dioxide in the atmosphere dropped, reducing Earth’s natural greenhouse effect and causing the “snowball Earth” with ice at or near the Equator. b. Global oxygen levels rose, killing many organisms adapted to live in an oxygen-poor world. c. The “great dying” mass extinction event began at the end of the Permian. d. both choice a and choice b e. all of choices a-c 2. Which of the following are required in order for natural selection to occur? a. Individuals in a population must exhibit variation in one or more traits. b. Traits in which variation occurs must be heritable. c. Inherited traits must affect the ability of an individual to survive and reproduce. d. More than one of the above, but not all of the above, are required for natural selection. e. All of the above are required for natural selection. 3. Which of the follow correctly describes why many astronomers look for alien signals in the radio part of the spectrum? a. Radio light is less likely than other forms of light to be absorbed by a planet’s atmosphere and the gas and dust between stars. b. Radio telescopes, unlike visible-light telescopes, can be used both day and night. c. A planet with a technological civilization could easily put out more radio light than that civilization’s star. d. All of the above are correct. e. None of the above are correct. 4. There have been five major mass extinction events during Earth’s history. Which of these events was likely caused by an asteroid colliding with Earth? a. the event at the end of the Ordovician b. the event in the late Devonian c. the event at the end of the Permian d. the event at the end of the Triassic e. the event at the end of the Cretaceous 5. The Cambrian Explosion occurred 539 Myr ago. For what percentage of its history did the Universe exist prior to the Cambrian Explosion? a. 96% b. 75% c. 25% d. 4% e. less than 1% 6. Imagine that a team of astronomers wants to resolve a continent on a planet orbiting the nearest star to the Sun. From our vantage point on Earth, the continent has an angular size of 4 x 10 -11 radians. The largest telescope available to the astronomers has a diameter of 10 m and they are observing the planet in light of wavelength 1 x 10 -6 m. Will the astronomers succeed?

Name: Do NOT write outside the box Astronomy 103, Exam 3 – Version A 4 a. No, they would need a telescope with a diameter of 3.1 x 10 16 m. b. No, they would need a telescope with a diameter of 30,500 m. c. Yes, they could have resolved the continent with a telescope whose diameter is only 6.1 m. d. Yes, they could have resolved the continent with a telescope whose diameter is only 4.9 x 10 -5 m. e. Yes, they could have resolved the continent with a telescope whose diameter is only 3.1 x 10 -5 m. 7. Imagine an alien civilization is attempting to directly image the inner planets in our Solar System. In what part of the electromagnetic spectrum should they look if they want the planets to be at their maximum brightness compared to the Sun? a. gamma rays b. ultraviolet c. visible d. infrared e. radio 8. You detect a radio signal at a particular frequency. You notice that the signal was modulated up and down around that frequency by 10 Hz. You translate the parts that were modulated up by 10 Hz into ones and the parts that were modulated down by 10 Hz into zeros. Doing so gives you the following string of 21 numbers: 0 0 0 0 1 0 1 1 1 0 1 0 1 0 1 1 0 1 0 0 0 21 is a semiprime number (i.e., it is what you get when you multiply together the prime numbers 3 and 7). Using this information, what does the signal represent? a. It is the word “HI.” b. It is the word “IT.” c. It is a (rough) picture of a human. d. It is a picture of a pyramid. Questions 9 and 10 refer to the timeline of the Universe shown below. 9. Which letter (a-d) most accurately marks the time when our Solar System formed? Choose “e” if you think we need an arrow even closer to the “Now” line than it is possible to show on this scale. 10. Which letter (a-d) most accurately marks the time when our species (Homo sapiens) first appeared on Earth. Choose “e” if you think we need an arrow even closer to the “Now” line than it is possible to show on this scale. The Big Bang 13.8 Gyr ago Now a b c d