1. What is the K-T boundary? a. The end of the Cretaceous time period and the beginning of the Tertiary b. The bottom of a 65 million-years-ago clay layer when the dinosaurs became extinct c. Both a and b are correct 2. Which of the following statements is true? a. Below the K-T boundary, there is a large diversity of species. b. Above the K-T boundary, there is a large diversity of species. 3. Which of the following statements is true? a. Below the K-T boundary, the foram species are smaller. b. Below the K-T boundary, the foram species are bigger. 4. Which of the following events are possible sources of high levels of iridium in sediments? Choose all that apply. a. An asteroid impact b. Rain c. Fossilized foraminifera d. A supernova 5. Which of the following pieces of evidence prompted researchers to abandon the hypothesis that a supernova caused the high levels of iridium in the K-T layer? Select one response. a. Coarse sediment mixed with uniform Cretaceous mud in Texas b. Differences in foraminifera fossils above and below the K-T boundary layer c. High levels of iridium in the K-T boundary layer d. Lack of an isotope of plutonium in the K-T boundary layer 6. How could an asteroid impact kill off so many different species? Select one response. a. Debris from the impact orbiting around the Earth shields sunlight, halting photosynthesis. b. Tsunamis, landslides, and earthquakes caused by the impact killed organisms near the site of impact. c. The impact was so extreme that life at ground zero was vaporized. d. Both A and C are possible. e. A, B and C are possible. 7. Why do we define the K-T event as a mass extinction event? Choose all that apply. a. Many species of foraminifera went extinct b. A large proportion of species went extinct c. The extinction occurred in many habitats around the world d. Tyrannosaur rex went extinct e. Many life forms near Gubbio, Italy were obliterated