Biologists believe that whooping cranes suffer from a high rate of developmental deformities of the spine and trachea
because of ____.
a. biological magnification of DDT
b. exposure to hormone-mimicking pollutants from plastics
c. a population bottleneck and loss of genetic variability
d. conservation biologists saving chicks that would have died at hatching
e. exposure to PCBs used as insulators in electronics
ANSWER: c
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A staphylococcal isolate that gives a negative result using the Cefinase disk and tests resistant to penicillin by disk diffusion means that:
a. the isolate may contain the mecA gene. b. the bacteria produce the lactamase en-zyme. c. the isolate is also resistant to ampicillin, carbenicillin, ticarcillin, and imipenem. d. the isolate is also resistant to oxacillin, cefoxitin, and ticarcillin-clavulanate.
Secondary metabolites are produced to
A. deter herbivores. B. deter competitors. C. aid in reproduction. D. aid in growth. E. deter competitors and aid in reproduction.
In 1980, only 1 to 5% of all Staphylococcus aureus isolates were MRSA strains. Now 60 to 70% of S. aureus isolates are MRSA strains. What process is the cause of this situation?
A) stabilizing selection of humans B) directional selection of humans C) directional selection of bacteria D) diversifying selection of bacteria
The process by which a relatively unspecialized cell becomes highly specialized is called _____.
A) degeneracy B) renaturation C) differentiation D) determination E) denaturation