All three domains (Bacteria, Archaea, and Eukarya) follow the same genetic code. Therefore, which of the following statements would most likely be correct?
A) The genetic code evolved three times.
B) The genetic code evolved before DNA replaced RNA as the unit of genetic information.
C) There were no mutations following the evolution of the genetic code.
D) The genetic code evolved before the different domains diverged.
Answer: D
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A) is involved in osmoregulation B) is responsible for excretion of undigested residue C) secretes a hypotonic solution D) concentrates electrolytes necessary for homeostasis in a hypertonic environment
Metabolic fingerprinting could be used ____
a. to determine the structure of a metabolite b. to compare the metabolic differences between healthy and disease cells c. to decipher the mRNA sequence of a metabolic enzyme d. to identify the sequence of a metabolic gene e. for paternity testing
Muscle, connective tissue, and the lining of some body cavities originate from which of the following germ layers?
a. mesoderm b. all of the choices c. ectoderm d. endoderm
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.