Life is believed to have originated at hydrothermal springs on the ocean floor rather than on near the surface of Earth. What conditions made the hydrothermal springs the likely place for the beginning of life?
Relate the conditions of the early oceans to the likely metabolism of the first cells.
What will be an ideal response?
Answer: Aside from the temperature, the environmental conditions of Earth would have been less hostile for life in hydrothermal springs than on land where exposure to UV light would have destroyed biological molecules. The springs also likely provided a steady supply of energy, such as H2 and H2S, and where the hot water interfaced with colder water likely served to form precipitates that eventually became life. The metabolism of the first cells did not depend on oxygen, as the atmosphere lacked molecular oxygen, but probably utilized electron transfer reactions between hydrogen, hydrogen sulfide, and reduced iron to produce energy.
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The amino acid glycine (C3NO2H6) is a(an):
A. element B. organic molecule C. inorganic molecule D. vitamin
The tools used by ecologists to study demography were developed by developmental biologists
Indicate whether the statement is true or false.
Desiccation, a time-honored method of preserving food, is effective because the
A) heat of the process kills microbes. B) freezing step of the process kills microbes. C) salt concentration is too low to support metabolic function. D) UV light used in the process of sun drying penetrates effectively. E) water content is too low to support metabolic function.
Three-year-old Ben's parents are ecstatic because he is now using the potty each time he needs to defecate. What muscle has Ben learned to control?
A. The Sphincter of Oddi made of smooth muscle B. The external anal sphincter made of striated muscle C. The internal anal sphincter made of smooth muscle D. The pyloric sphincter made of smooth muscle E. The cardiac sphincter made of striated muscle