Severe acute respiratory syndrome (sars) is caused by sars-associated coronavirus (sars-cov).  the diagram shows the structure of sars-cov.

sars emerged as an infectious human disease in 2002.  several years of research have led to the conclusion that sars-cov originated in a single colony of bats.  these bats served as a reservoir for a form of the virus which could not infect humans.  sars-cov is hypothesized to have mutated in such a way that it gained the ability to infect humans.
in what way are the glycoproteins on sars-cov involved in its ability to infect humans?
  a. 
the glycoproteins the virus travel in the air so it can spread among humans.
  b. 
the glycoproteins interact with a human cell's dna replication machinery so the virus can replicate.
  c. 
the glycoproteins the virus move around the human respiratory tract so it can damage the lungs.
  d. 
the glycoproteins interact with receptors on a human cell so the virus can enter the cell.

Ajet plane has a sound level of 120 db at a distance of 60 m. what is the q23. sound level at a distance of 6.0 km? (60)2 (6000)? om solution 80db db, hint: 16x assume ultrasound waves travel through the body of an animal at 1540 q24. m/s. if a 30,000 hz signal were reflected off a portion of a heart which was moving toward the source at 3 m/s, what frequency signal would return to the stationary source? solution 30.117hz

Which type of bond is found between the atoms of a molecule? a. metallic b. delocalized electron c. covalent d. ionic

The frequency of vibrations of a vibrating violin string is given by f = 1 2l t ρ where l is the length of the string, t is its tension, and ρ is its linear density.† (a) find the rate of change of the frequency with respect to the following. (i) the length (when t and ρ are constant) (ii) the tension (when l and ρ are constant) (iii) the linear density (when l and t are constant) (b) the pitch of a note (how high or low the note sounds) is determined by the frequency f. (the higher the frequency, the higher the pitch.) use the signs of the derivatives in part (a) to determine what happens to the pitch of a note for the following. (i) when the effective length of a string is decreased by placing a finger on the string so a shorter portion of the string vibrates df dl 0 and l is ⇒ f is ⇒ (ii) when the tension is increased by turning a tuning peg df dt 0 and t is ⇒ f is ⇒ (iii) when the linear density is increased by switching to another string df dρ 0 and ρ is ⇒ f is ⇒