The sputum of a 75-year-old man with chronic lung infections yields the following: • Many gram-negative coccobacilli in Gram stain • X and V factors required for growth • Nonhemolytic on rabbit blood agar The organism can be identified as:
a. Haemophilus aegyptius.
b. H. parainfluenzae.
c. Haemophilus haemolyticus.
d. H. influenzae.
D
H. influenzae is nonhemolytic on rabbit blood and requires both X and V factors to grow. Al-though H. aegyptius and H. haemolyticus both require X and V factors for growth, they are he-molytic on rabbit blood. H. parainfluenzae requires only V factor and is variable for <-hemolysis.
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Which of the following is an example of a subunit vaccine?
A) The surface protein of a virus is used to make the vaccine. B) The virus is exposed to ultraviolet light. C) The virus is exposed to formaldehyde. D) The virus is grown in a host other than humans and thus grows more slowly than normal.
The sequence of a promoter constitutes the most basic mechanism of transcription regulation because:
A. promoters are always bound by activators. B. RNA polymerase has differential affinities for different sequences that correlate with the efficiency of transcription. C. promoters are always bound by repressors. D. the expression levels of different housekeeping genes are always identical.
Receptors for polar molecules are found ____, while receptors for nonpolar molecules are located ____
a. on the cell surface; within the cell b. within the cell; on the cell surface c. on the cell surface; on the nuclear membrane d. on the nuclear membrane; on the cell surface e. on the cell surface; within the lipid bilayer
With __________, an animal modifies a voluntary behavior in response to the behavior's
consequences. Fill in the blank(s) with the appropriate word(s).