*Question*
Answer the following question given this paragraph: It's easy to get lost in the discussion of dinosaurs and theories about why they went extinct 65 million years ago. Was it due to a meteor slamming into Earth near the coast of modern-day Mexico, or was it from some long-term weather cycle that is not yet understood? One hypothesis that will never be proposed is that humans had something to do with it. Mammals were small, insignificant creatures of the forest 65 million years ago, and no humans existed. Woolly mammoths, however, began to go extinct about 10,000 years ago, when they shared the Earth with humans who were no different anatomically than humans today (Figure 45.12). Mammoths survived in isolated island populations as recently as 1700 BC. We know a lot about these animals from carcasses found frozen in the ice of Siberia and other regions of the north. Scientists have sequenced at least 50 percent of its genome and believe mammoths are between 98 and 99 percent identical to modern elephants. It is commonly thought that climate change and human hunting led to their extinction. A 2008 study estimated that climate change reduced the mammoth's range from 3,000,000 square miles 42,000 years [7] ago to 310,000 square miles 6,000 years ago. It is also well documented that humans hunted these animals. A 2012 study showed that no single factor was exclusively responsible for the extinction of these [8] magnificent creatures. In addition to human hunting, climate change, and reduction of habitat, these scientists demonstrated another important factor in the mammoth's extinction was the migration of humans across the Bering Strait to North America during the last ice age 20,000 years ago. The maintenance of stable populations was and is very complex, with many interacting factors determining the outcome. It is important to remember that humans are also part of nature. Once we contributed to a species' decline using primitive hunting technology only. Q: Mammoths, close genetic relatives of modern elephants, are believed to have gone extinct due to hunting by humans and what factor? Choices: - volcanic eruptions - earthquakes - migration change - climate change A:
**Answer**
climate change

*Question*
Answer the following question given this paragraph: Basic Principles of Gas Exchange Gas exchange during respiration occurs primarily through diffusion. Diffusion is a process in which transport is driven by a concentration gradient. Gas molecules move from a region of high concentration to a region of low concentration. Blood that is low in oxygen concentration and high in carbon dioxide concentration undergoes gas exchange with air in the lungs. The air in the lungs has a higher concentration of oxygen than that of oxygen-depleted blood and a lower concentration of carbon dioxide. This concentration gradient allows for gas exchange during respiration. Partial pressure is a measure of the concentration of the individual components in a mixture of gases. The total pressure exerted by the mixture is the sum of the partial pressures of the components in the mixture. The rate of diffusion of a gas is proportional to its partial pressure within the total gas mixture. This concept is discussed further in detail below. Q: Gas exchange during respiration occurs primarily through what? Choices: - vaporization - secretion - activation - diffusion A:
**Answer**
diffusion

*Question*
Answer the following question given this paragraph: Normal light microscopes can magnify objects up to about 1,500 times. Electron microscopes can magnify objects up to 1,000,000 times. Why can electron microscopes magnify images so much? A microscope's resolution depends on the wavelength of light used. The smaller the wavelength, the more a microscope can magnify. Light is a wave, and, as such, it has a wavelength associated with it. The wavelength of visible light, which is detected by the eyes, varies from about 700 nm to about 400 nm. One of the startling conclusions about modern science is that electrons also act as waves. However, the wavelength of electrons is much, much shorterabout 0.5 to 1 nm. This allows electron microscopes to magnify 600700 times more than light microscopes. This allows us to see even smaller features in a world that is invisible to the naked eye. Atoms act the way they do because of their structure. We already know that atoms are composed of protons, neutrons, and electrons. Protons and neutrons are located in the nucleus, and electrons orbit around the nucleus. But we need to know the structural details to understand why atoms react the way they do. Virtually everything we know about atoms ultimately comes from light. Before we can understand the composition of atoms (especially electrons), we need to understand the properties of light. Q: While normal light microscopes can magnify objects up to about 1,500 times, what advanced instruments can magnify objects up to 1,000,000 times? Choices: - magnetic microscopes - micro microscopes - electric microscopes - electron microscopes A:
**Answer**
electron microscopes

*Question*
Answer the following question given this paragraph: Q: Which stage of life is typically easier for learning multiple languages? Choices: - adolescenc - infancy - adulthood - childhood A:
**Answer**
childhood