The term "reducing atmosphere" for the early Earth means that the atmosphere
A. contained little or no carbon dioxide.
B. contained little or no free nitrogen.
C. was much thinner around the surface of the Earth than now.
D. contained only two or three kinds of gases.
E. contained little or no free oxygen.
Answer: E
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Life is thought to have evolved from complex molecules formed by the interaction of smaller molecules in oceans and the atmosphere. The substance which brought these molecules together to interact is
A. buffers. B. acids. C. water. D. salts. E. hydrogen.
Which is incorrect about the Fc region of an immunoglobulin?
A. It contains an effector molecule that can bind to cells such as macrophages and mast cells. B. It is called the crystallizable fragment. C. It determines the class to which the immunoglobulin belongs. D. It contains an effector molecule that can fix complement. E. It forms the antigen binding sites.
A dietary Calorie equals 1 kilocalorie. Which of the following statements correctly defines 1 kilocalorie? One kilocalorie equals _____
A) 1000 calories, or the amount of heat required to raise the temperature of 1 g of water by 1°C B) 10,000 calories, or the amount of heat required to raise the temperature of 1 kg of water by 1°F C) 1000 calories, or the amount of heat required to raise the temperature of 1 kg of water by 1°C D) 1000 calories, or the amount of heat required to raise the temperature of 100 g of water by 100°C
Fungi are
A. saprophytes. B. mutualistic. C. decomposers. D. All of the above are correct.