The author include the point about $4 billion dollars a day being spent on healthcare in the united states to illustrate all the following except a. americans use a lot of health care services. b. health care is an important part of an economy. c. a lot of money is spent on healthcare in the united states. d. americans spend far more on healthcare than those in other nations.

Astructural difference between the trachea and esophagus that prevents the trachea from collapsing is the presence of: a) smooth muscle b) skeletal muscle c) respiratory cilia d) rings of cartilage

Avirus consisting of a single strand of rna, which is transcribed into complementary dna, is a ) proteaseb) retrovirusc) rna replicase virusd) nonenveloped virus

Which of the following processes within viral replication is the greatest source of genetic variation in rna virus populations? a) high mutation rate due to lack of proofreading of rna genome replication errors.b) transcription from the host cell rna polymerase introduces numerous mutations.c) capsid proteins from the host cell can replace the viral capsid.d) viral rna is translated by host cell ribosomes.