Answer the following question given this paragraph: Over much of Earth's past, the climate was warmer than it is today. Picture in your mind dinosaurs roaming the land. They're probably doing it in a pretty warm climate! But ice ages also occurred many times in the past. An ice age is a period when temperatures are cooler than normal. This causes glaciers to spread to lower latitudes. Scientists think that ice ages occurred at least six times over the last billion years alone. How do scientists learn about Earth's past climates?. Q: What do you call a period when temperatures are cooler than normal, causing glaciers to spread? Choices: - polar age - earth age - thermal age - ice age A:
ice age

Answer the following question given this paragraph: Scientists have built machines called particle accelerators. These amazing tools smash particles that are smaller than atoms into each other head-on. This creates new particles. Scientists use particle accelerators to learn about nuclear fusion in stars. They can also learn about how atoms came together in the early universe. Two well-known accelerators are SLAC, in California, and CERN, in Switzerland. Q: What amazing machines smash particles that are smaller than atoms into each other head-on? Choices: - nitrogen accelerators - observant accelerators - absorption accelerators - particle accelerators A:
particle accelerators

Answer the following question given this paragraph: Figure 11.3 Crossover occurs between non-sister chromatids of homologous chromosomes. The result is an exchange of genetic material between homologous chromosomes. Q: Crossover occurs between non-sister chromatids of which chromosomes? Choices: - analogous - identical chromosomes - compound chromosomes - homologous A:
homologous