For most pathogens to be diagnostic of current infection, there must be a(n) _____ in the patient's antibody titer of _____ doubling dilutions
a. decrease; two
b. increase; two
c. decrease; four
d. increase; four
B
A fourfold rise in titer, that is, an increase in the patient's titer of two doubling dilutions, is con-sidered to be diagnostic of current infection.
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An earthquake decimates a ground-squirrel population, killing 98% of the squirrels. The surviving population happens to have broader stripes, on average, than the initial population. If broadness of stripes is genetically determined,
what effect has the ground-squirrel population experienced during the earthquake? A) directional selection B) disruptive selection C) a founder event D) a genetic bottleneck E) gene flow
____ in angiosperms occurs when a sperm cell "fertilizes" a diploid (2n) cell within the future seed (eventually forming a triploid (3n) endosperm), and a second sperm fertilizes a haploid (1n) egg
Fill in the blank with the appropriate word.
A bundle of ____ extends from the base to the tip of a eukaryotic flagellum or cilium
a. microtubules b. microfilaments c. actin d. cytokeratin e. intermediate filaments
Which of the following is NOT an organic molecule?
a. cholesterol b. ATP c. water d. glucose e. lipid