midterm guide. solution

midterm guide. solution - MT1-Answer Key Question 1 correct...

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MT1-Answer Key Question 1 – correct answer D A – Not correct, the three domains of life are Eubacteria, Archaebacteria and Eukaryotes. Eubacteria and Archaebacteria are both Prokaryotic. B – The opposite is true, Eukaryotes have a nucleus and Eubacteria have a nucleoid C – The lower limit of cell size is a result of the minimum concentration of all of the essential biomolecules, not just the genetic information. D – This is correct for both aerobic and anaerobic cells E – Anabolism is the synthetic pathway, Catabolism is the breakdown of structured molecules. Question 2 – correct answer C and E A – Most notably organic compounds were created from inorganic compounds B – The conditions of the atmosphere used for the experiment was a mimic of what the atmosphere of early Earth was like. The point of the experiment was that evolution of organic molecules can spontaneously generate with suitable energy input. C – This is mostly correct, but they never actually froze the mixture, they just cooled the gas with a condenser to make the reaction continuous D – Yes this was one of the goals of the experiment E – The RNA world hypothesis was based upon the discovery that RNA could perform as an enzyme and was not part of the Urey-Miller experiment. Interestingly, Joan Oro was able to synthesize the nucleotide bases using hydrogen cyanide under a reducing atmosphere. Question 3 – correct answer C A – Yes, this is the point of a buffer B – This is true, although certain buffer mixtures can have multiple pKa values so a buffer may be suitable over a wide range of pH values C – A buffer is typically made of a weak acid and its conjugate base or a weak base and its conjugate acid. Strong acids and strong bases can buffer well at extreme pH. The statement “A buffer is made up of a strong acid and its conjugate base” is false because a buffer can also be made from a weak acid, weak base or strong base. D – We want the pH change to be minimal over the buffering region so the titration curve should be flat E – This is true because the dissociation constant of water increases with increasing temperature. The real pH can also be affected by temperature because the amount of dissolved CO2 from the atmosphere will vary with temperature Question 4 – correct answer B and E A – This is basically the definition of a strong electrolyte. This is why strong electrolytes are good conductors of electricity B – False. Even weak electrolytes can dissociate in water. C – pH = pKa + log([A-]/[HA]). At 50/50 [A-]/[HA] is 1 and the log(1) is 0, so pH = pKa D – This is a property of electrolytes.
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E – False. One of the above statements (B) is false, therefore statement E is also False.
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midterm guide. solution - MT1-Answer Key Question 1 correct...

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