The rRNA gene sequences of hyperthermophilic Archaea and Bacteria have diverged ________ over time, likely due to ________
A) relatively little / strong constraints on sequence changes at higher temperatures
B) substantially / higher mutation rates at higher temperatures
C) relatively little / low mutation rates in these ancient organisms
D) substantially / DNA damage at higher temperatures
Answer: A
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A microbiologist inoculates Staphylococcus epidermidis and Escherichia coli into a culture medium. Following incubation, only the E. coli grows in the culture. What is the most likely explanation?
A. The microbiologist used too much inoculum. B. The culture medium was differential. C. The culture was contaminated. D. The incubation temperature was incorrect. E. The culture medium was selective.
A gelatinous fluid inside the chloroplast containing ribosomes, DNA, and enzymes is the
A. chlorophyll. B. mitochondrion. C. stroma. D. thylakoid. E. granum.
Which of the following statements is correct?
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Which of the statements below is true about
warfarin? a. It is a very effective rodenticide. b. It interferes with blood clotting in rats. c. Rats that are resistant to warfarin possess a gene that is rare among vulnerable rats. d. It is an agent of natural selection in rats. e. All of these are true.