Answer the following question given this paragraph: Gastrin, which signals the secretion of gastric acid. Q: What signals the secretion of gastric acid? Choices: - hormone - pepsin - leptin - gastrin A:
gastrin
Answer the following question given this paragraph: Why is activation energy needed? A reaction won't occur unless atoms or molecules of reactants come together. This happens only if the particles are moving, and movement takes energy. Often, reactants have to overcome forces that push them apart. This takes energy as well. Still more energy is needed to start breaking bonds in reactants. The graphs in Figure below show the changes in energy in endothermic and exothermic reactions. Both reactions need the same amount of activation energy in order to begin. Q: What is required to break bonds in reactants? Choices: - food - gas - protein - energy A:
energy
Q: Answer the following question given this paragraph: Cells may be small in size, but they are extremely important to life. Like all other living things, you are made of cells. Cells are the basis of life, and without cells, life as we know it would not exist. You will learn more about these amazing building blocks of life when you read this chapter. Q: What basic structures are called the building blocks of life and comprise all living things? Choices: - pigments - seeds - lipids - cells A:
A: cells
Question: Answer the following question given this paragraph: A variable is a factor that can change over the course of an experiment. Independent variables are factors whose values are controlled by the experimenter to determine its relationship to an observed phenomenon (the dependent variable). Dependent variables change in response to the independent variable. Q: The values of which factors are controlled by the experimenter over the course of an experiment? Choices: - other variables - independent elements - independent approaches - independent variables A:
Answer: independent variables
*Question*
Answer the following question given this paragraph: The outer planets in the solar system are giant balls of swirling gas. Earth and the other inner planets are relatively small, dense, and rocky. Most of Earth's surface is covered with water. As far as we know, Earth is also the only planet that has liquid water. Earth's atmosphere has oxygen. The water and oxygen are crucial to life as we know it. Earth appears to be the only planet in the solar system with living creatures. You can learn more about the planets in the Our Solar System chapter. Q: What is most of earth's surface covered with? Choices: - insects - sand - silicon - water A:
**Answer**
water
*Question*
Answer the following question given this paragraph: Ceramics A ceramic is any nonmetallic, inorganic solid that is strong enough for use in structural applications. Traditional ceramics, which are based on metal silicates or aluminosilicates, are the materials used to make pottery, china, bricks, and concrete. Modern ceramics contain a much wider range of components and can be classified as either ceramic oxides, which are based on metal oxides such as alumina (Al2O3), zirconia (ZrO2), and beryllia (BeO), or nonoxide ceramics, which are based on metal carbides such as silicon carbide (carborundum, SiC) and tungsten carbide (WC), or nitrides like silicon nitride (Si 3N4) and boron nitride (BN). All modern ceramics are hard, lightweight, and stable at very high temperatures. Unfortunately, however, they are also rather brittle, tending to crack or break under stresses that would cause metals to bend or dent. Thus a major challenge for materials scientists is to take advantage of the desirable properties of ceramics, such as their thermal and oxidative stability, chemical inertness, and toughness, while finding ways to decrease their brittleness to use them in new applications. Few metals can be used in jet engines, for example, because most lose mechanical strength and react with oxygen at the very high operating. Q: What is any nonmetallic, inorganic solid that is strong enough for use in structural applications called? Choices: - tissue - metallic - glass - ceramic A:
**Answer**
ceramic