The lower respiratory tract is protected by all of the following EXCEPT
A) competition with the normal flora of the lungs.
B) IgA antibodies.
C) mucous secretions.
D) the ciliary escalator.
E) alveolar macrophages.
A
You might also like to view...
In a lake, a certain native species of zooplankton is found evenly distributed in the water column. After
introduction of a different species of zooplankton, the native species is only found in the shallow water zone. This is most likely an illustration of: a. character displacement. b. species richness. c. primary succession. d. secondary succession. e. competitive exclusion.
Members of the lineage ____ are commonly called chitons. They have a dorsal shell divided into eight
plates that allow it to conform to irregularly shaped surfaces.
a. Cephalopoda b. Polyplacophora c. Bivalvia d. Gastropoda e. Scaphopoda
Are flowering plants haploid-dominant or diploid-dominant? What will be an ideal response?
Which of the following processes best explains the diversity of human รก-tropomyosin proteins?
a. the wobble hypothesis b. exon shuffling c. alternative splicing d. degeneracy