One theory holds that the first self-replicating molecules were
A) carbohydrates.
B) lipids.
C) RNA.
D) DNA.
E) amino acids.
C
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Air movement to the mammalian respiratory surfaces can be reduced when smooth muscle in the walls
of the ____ contract(s).
a. epiglottis b. bronchioles c. large bronchi d. trachea e. aorta
The intestinal parasite Ascaris lumbricoides currently infects more than one billion people. Which group is it in?
a. flatworms b. roundworms c. annelids d. cnidarians e. arthropods
The Irish potato famine in the mid-1840s was caused by a heterotrophic protist, Phytophthora infestans, which caused widespread infection of potato plants. It was successful in infecting because it was
A. a protozoan, with flagella, and swimming to potato plants in wet seasons, engulfing and digesting the potato cells. B. a red algae, able to perform photosynthesis, allowing its cells to spread from the coast to potato farm fields. C. a water mold, and its soft, fleshy filaments benefitted from several rainy seasons. D. a diatom, with a silica shell allowing it to survive the soil conditions in which potatoes grow as specialized roots. E. a ciliate, which has filaments very similar to water and slime molds.
Land vertebrates evolved which of the
following to help maintain water balance? a. circulatory system b. thyroid c. kidneys d. liver e. none of these