A problem with the basic Oparin-Haldane model for the origin of life (though not necessarily an unsolvable one) is that ________
A) it does not explain the origin of chirality
B) the early Earth is now not thought to have had a highly reducing atmosphere
C) monomers have to be chemically activated before they will polymerize
D) purine bases can attach to sugars in many equally probable ways
E) All of the above.
E
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What kind of bacterial variant would be most likely to survive in the human digestive system?
A) a variant that thrives at temperatures close to 100°C B) a variant with a coating that is resistant to an acidic environment C) a variant that reproduces slowly D) a variant that easily attaches to hard surfaces
A dividing cell lacks a nuclear membrane, contains chromosomes consisting of two chromatids, and has clearly visible chromosomes. It is in which one of the following stages?
A. metaphase B. anaphase C. interphase D. telophase
All of the following could be reasons why antimicrobic treatment fails except
A. a disk diffusion test showing pathogen sensitivity to the antimicrobic. B. not completing the full course of treatment. C. the inability of the drug to diffuse into the infected body compartment. D. a mixed infection where some of the pathogens are drug resistant. E. diminished gastrointestinal absorption due to an underlying condition or age.
? Sheets can participate in the formation of amyloid fibers, which are insoluble protein aggregates. What drives the formation of amyloid fibers?
(a) denaturation of proteins containing ? sheets (b) extension of ? sheets into much longer ? strands (c) formation of biofilms by infectious bacteria (d) ?-sheet stabilization of abnormally folded proteins