The portion of the molecule in box 3 of Figure 12-1 is:
a. a sugar.
b. a protein.
c. a pyrimidine.
d. a purine.
e. a nucleotide.
D
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Which of the following statements is FALSE?
A) When plant cells are growing, they release expansins, which are enzymes that can expand the primary cell wall. B) The secondary cell wall often contains structural components, like lignin, that form a relatively rigid and complex network within the cell wall. C) A plant cell continues growing after the secondary cell wall forms but stops growing with the formation of the tertiary cell wall. D) Pectin is a component of the cell wall that attracts and holds water.
Hawaiian honeycreeper diversity is best
described as an example of
a. behavioral isolation. b. morphological convergence. c. exaptation. d. adaptive radiation. e. sympatric speciation
Distilled water is ____ to body cells
a. isotonic b. hypertonic c. hypotonic d. protonic
e. aquatonicWhich epidermal cell produces the pigments that lead to the coloration of the skin?
a. Collagen fibers b. Keratinocytes c. Melanocytes d. Stratified squamous epithelium e. Elastin fibers