The capsule in streptococcus pyogenes is considered a virulent factor because it
A. is antiphagocytic
B. binds to epithelial cells
C. mediates internalization by host cells
D. degrades complement component C3b
E. binds to IgM and IgG
Ans: A. is antiphagocytic
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Selection pressures acting on a population may
favor a. individuals at the left end of the range of variation. b. individuals at the right end of the range. c. extreme individuals at both ends of the range. d. the intermediate individuals within the range. e. all of these.
Which of the following is a type of postzygotic
reproductive isolating mechanism? a. temporal isolation b. mechanical isolation c. behavioral isolation d. hybrid sterility e. all of these
Which of the following is NOT an accessory organ
of the human digestive system? a. salivary gland b. esophagus c. pancreas d. gallbladder e. liver
Which of the following specifically describes the movement of air into and out of the lungs?
A) internal respiration B) pulmonary ventilation C) respiration D) secondary ventilation E) expiration