Drug-resistant populations of microbes arise when
A) exposure to drugs selectively kills sensitive cells, allowing overgrowth of resistant cells.
B) exposure to drugs causes mutations that produce resistance.
C) resistant cells become numerous in a population due to their greater vigor.
D) the patient becomes immune to the drug.
E) synergy between medications occurs.
A
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Which of the following do researchers suspect is an important factor in colony collapse disorder (CCD?)
a. Habitat fragmentation caused by land development inhibits a bee’s chance of finding a reproductive partner. b. Long-term exposure to low levels of insecticides impair a plant’s ability to produce nectar that a bee can use. c. Exposure to extremely high levels of herbicides can kill an entire population of plants and the bees that depend on them. d. Herbicides kill the plants that bees pollinate thereby eliminating the source of nectar for a bee. e. Long-term exposure to low levels of insecticides impair a bee’s ability to navigate and communicate.
Nucleosomes are best described as:
a. eukaryotic DNA associated with histone proteins. b. prokaryotic DNA associated with nonhistone proteins. c. eukaryotic DNA associated with nonhistone proteins. d. prokaryotic DNA associated with histone proteins. e. eukaryotic DNA associated with scaffolding proteins.
The hematocrit is a measuure of the percentage of whole blood occupied by
a) WBC b) platelets c) RBCs d) plasma e) plasma proteins
In the adaptive immune response, effective immunity cannot be detected for several days after the first contact with the pathogen
Indicate whether the statement is true or false.