After a biology field trip, you make a thin section of a flowering plant stem. You observe these two main sets of cells: the lower set of cells is large, has thick walls, and tests positive for the lignin molecule, while the smaller, but uniform red cells do not have lignin. From this evidence, you conclude that the larger cells with lignin are
A. rhizoids.
B. phloem.
C. xylem.
D. cuticles.
E. stomata.
C. xylem.
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Which of the following effects can occur because of the high surface tension of water?
A) Lakes cannot freeze solid in winter, despite low temperatures. B) A raft spider can walk across the surface of a small pond. C) Organisms can resist temperature changes, although they give off heat due to chemical reactions. D) Sweat can evaporate from the skin, helping to keep people from overheating. E) Water can flow upward from roots to the leaves in plants.
Which of the following has flagella that wave back and forth?
A. Archaea B. Eukarya C. Bacteria
Before biotechnology, human proteins used in treatment of diseases were
A. not available. B. synthesized chemically. C. substituted for by similar animal proteins. D. harvested from blood or cadavers. E. substituted for by similar animal proteins and harvested from blood or cadavers only
Long-range, two-way movement behavior in animals is termed ________.
Fill in the blank(s) with the appropriate word(s).