Rheumatic fever is a sequalae of repeated infection with streptococcus pyogenes. The pathogenesis involved in this complication is
A. Antigen-antibody complex precipitation on the valves of the heart
B. Molecular mimicry in which some of the bacterial proteins resembles those of endocardium
C. An immunological response to a specific Protein A
D. An immunological response in the antigen determining the Lancefield classification of the bacterium
Ans: B. Molecular mimicry in which some of the bacterial proteins resembles those of endocardium
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Which of the following statements about proteoglycans is TRUE?
A. Proteoglycans are composed of collagen. B. Proteoglycans are composed of polysaccharides called glycosaminoglycans. C. Proteoglycans provide resistance to compression. D. Proteoglycans are both composed of collagen and provide resistance to compression. E. Proteoglycans are both composed of polysaccharides called glycosaminoglycans and provide resistance to compression.
What limits the frequency of action potentials?
A. chloride ions B. spike amplitude C. nodes of Ranvier D. refractory period
A diploid (2n) hyphal cell of Neurospora crassa will take the next step in its life cycle by ________
a. breaking open to disperse spores b. undergoing meiosis to produce ascospores c. undergoing mitosis to produce more 2n hyphal cells d. finding a compatible strain and completing cytoplasmic fusion
While each of these processes are believed to have evolved prior to aerobic respiration, which one is the most critical process, without which aerobic respiration could never have developed?
A. Oxygenic photosynthesis B. Anoxygenic photosynthesis C. Lactic acid fermentation D. Alcohol fermentation