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TLS Online TPP Program

#Question id: 5761

E. coli cells were spread on an agar plate, producing 1000 colonies.  The colonies are replica plated on two agar plates containing the antibiotic kanamycin and one agar plate without antibiotics.  All of the colonies are able to grow on the agar plate without antibiotic but only 4 colonies are able to grow on each of the agar plates containing kanamycin.  You notice that the four colonies that grew on each of the kanamycin containing plates are in the exact same position.  This demonstrates

#8. Inheritance Biology

  1. how to screen for environmental mutagens

  2. that mutations occur in prokaryotes as well as in eukaryotes

  3. that in some cases mutations are caused by the selective agent itself

  4. a direct correlation between the amount of the selective agent used and the number of resistant mutants (one-hit relationship)

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TLS Online TPP Program

#Question id: 387

#1. Molecules and their Interaction Relevant to Biology

For a weak acid with a pKa of 6.0, What would be the ratio of acid to salt at pH 5.
TLS Online TPP Program

#Question id: 389

#1. Molecules and their Interaction Relevant to Biology

A weak acid HA has a pKa of 5.0.  If 1.0 mol of this acid and 0.1 mol of NaOH were dissolved in one liter of water, what would the final pH be?
TLS Online TPP Program

#Question id: 390

#1. Molecules and their Interaction Relevant to Biology

What are the properties arising due to varying concentrations of solute in a given solvent, irrespective of the nature of solute with respect to the solvent?
TLS Online TPP Program

#Question id: 391

#1. Molecules and their Interaction Relevant to Biology

In a hospital laboratory, a 10.0 mL sample of gastric juice, obtained several hours after a meal, was titrated with 0.1 M NaOH to neutrality; 7.2 mL of NaOH was required. The patient’s stomach contained no ingested food or drink, thus assume that no buffers were present. What was the pH of the gastric juice?
TLS Online TPP Program

#Question id: 393

#1. Molecules and their Interaction Relevant to Biology

Carbon dioxide (CO2) is readily soluble in water, according to the equation CO2 + H2O ↔ H2CO3. Carbonic acid (H2CO3) is a weak acid. If CO2 is bubbled into a beaker containing pure, freshly distilled water, which of the following graphs correctly describes the results?
TLS Online TPP Program

#Question id: 400

#1. Molecules and their Interaction Relevant to Biology

Consider two solutions: solution X has a pH of 4; solution Y has a pH of 7. From this information, we can reasonably conclude that ________.