(Q).
Answer the following question given this paragraph: Wings are an obvious adaptation for flight. They are actually modified front legs. Birds move their wings using muscles in the chest. These muscles are quite large, making up as much as 35 percent of a bird's body weight. Q: In birds, modified front legs are actually what? Choices: - tails - arms - claws - wings A:
(A).
wings

(Q).
Answer the following question given this paragraph: Fuels According to the law of conservation of energy, energy can never actually be "consumed"; it can only be changed from one form to another. What is consumed on a huge scale, however, are resources that can be readily converted to a form of energy that is useful for doing work. As you will see in Chapter 18 "Chemical Thermodynamics", energy that is not used to perform work is either stored as potential energy for future use or transferred to the surroundings as heat. A major reason for the huge consumption of energy by our society is the low efficiencyof most machines in transforming stored energy into work. Efficiency can be defined as the ratio of useful work accomplished to energy expended. Automobiles, for example, are only about 20% efficient in converting the energy stored in gasoline to mechanical work; the rest of the energy is released as heat, either emitted in the exhaust or produced by friction in bearings and tires. The production of electricity by coal- or oilpowered steam turbines is significantly more efficient (Figure 5.17 "Electricity from Coal"): about 38% of the energy released from combustion is converted to electricity. In comparison, modern nuclear power plants can be more than 50% efficient. Figure 5.17 Electricity from Coal. Q: Fuels according to the law of what, can never actually be "consumed"; it can only be changed from one form to another? Choices: - use of energy - expansion of energy - difference of energy - conservation of energy A:
(A).
conservation of energy

(Q).
Answer the following question given this paragraph: Blood travels through the bicuspid valve to the left atrium. Both the aortic and the pulmonary valves are semilunar valves. The mitral valve is an atrioventricular valve. Figure 40.17 Varicose veins are veins that become enlarged because the valves no longer close properly, allowing blood to flow backward. Varicose veins are often most prominent on the legs. Why do you think this is the case?. Q: Varicose veins are veins that become enlarged because the valves no longer do this? Choices: - shrink properly - open properly - enlarge properly - close properly A:
(A).
close properly