POST-CLASS QUESTIONS for Week #4
(individual; open book; turn in June 17, 2008)
(Lose 20% if handed in June 18; lose everything if later!)

NAME

Grades will be curved providing you correctly answer at least 4 of these:

E 1. Bakers yeast is
(a) a type of bacterium
(b) a prokaryote containing both DNA and RNA
(c) incapable of growing independent of a host cell
(d) b and c only
(e) none of the above
Yeast is a fungus and thus eukaryotic. Used in levening bread, it obviously doesn't need host cells in which to grow. E 8. Consider: (A) Streptococcus lactis, (B) Salmonella typhimurium and (C) Candida albicans. Which have any plausibilty for being "probiotic"?
(a) A + B + C
(b) A + B
(c) A + C
(d) B + C
(e) only one of the species
(f) none of them
A is a dairy bacterium
B causes mouse typhoid and human trots
C causes trench mouth and vaginitis
C 2. Bakers yeast
(a) causes vaginitis
(b) possesses a cell wall, nucleus, chloroplasts and cytoplasm
(c) can be stained with methylene blue to increase microscopic contrast
(d) is in the Kingdom "Planta."
(e) all of the above
(f) none of the above
It might cause vaginitis in immunocompromised people (e.g.: with AIDS). Doesn't have chloroplasts; Fungi, not Planta. A 9. Honey expt: which horizontal row of disks exhibits a temperature of inactivation? (numbers on disks indicate subjecting the honey to that temmperature for 15 minutes and these were placed on a freshly seeded lawn of susceptible bacteria and then incubated overnight)
All 20's disks are controls and should have halos, but only A does.
C 3. Bacteria and viruses:
(a) both always contain DNA
(b) both can be revived from the "dead" state
(c) neither has mitochondria
(d) all of the above
(e) only a and c
(f) none of the above
Not A because RNA-viruses exist. Prokaryotes have no organelles: not nuclei, nor mitochondria...
D 10. Honey expt: Which horizontal set of disks indicate that the antibacterial agent is NOT a protein. Similar setup as with the previous question except that the treatments are different: "M" = meat tenderizer (papaine); "P" = pepsin; "B" = both
B and C don't make sense as the "both" disks should have halos if one or the other or both the M and P have a halo.
E 4. The US Dept of Health and Human Services contains
(a) the National Institutes of Health
(b) The Food and Drug Administration
(c) The Centers for Disease Control and Prevention
(d) The Consumer Protection Agency
(e) only two of the above
FDA is a subdivision of the Dept. Agriculture
CPA
B 11. Honey expt: Mary Lou dialyzed her honey, which resulted in
(a) her dialysis "sausage" shriveling to near nothing
(b) her "sausage" osmotically exploded
(c) her "sausage" didn't change in volume
You are all part of a team and should know what the others are doing! You saw the dialysis tubing enlarge as it hung in the flowing water at the sink for several hours. If it hadn't been removed, it would have exploded.
B 5. Considering the tiers in the pyramid of life,
(a) the mass of all plants is greater than the mass of any other tier
(b) the greatest bulk of all actively growing cells is mostly that of microöorganisms
(c) in the food chain, animals eat the plants, which eat the fungi, which eat the bacteria
(d) only plants are photosynthetic and thus the source of fixed-carbon supporting all other tiers of life
(e) all of the above
(f) only two of the above, but not e
not C: plants eat sunlight and minerals but not fungi;
not D: some bacteria photosynthesize (remember Beggiatoa from the previous week's ML quiz!
B 12. Honey expt: Cheryl's dialysis "sausage" was at first dialyzed against water, and then excess water was reverse-osmosed from the "sausage" such that the volume became equal to that of the honey she originally used. This was then "disked" and set on fresh lawns of bacteria. Which horizontal set indicates the antibacterial agent was a small molecule? (H = raw honey control; D = dialyzed)
Not A or C as the H (control) didn't have halos.
Not D because agent didn't diffuse away through the tubing.
C 6. Cheryl made a 10-fold serial dilution and plated 10μL samples on a plate she labeled "C-2." The next day she obtained these counts in her four lanes:
TMTC, TMTC, 58, 7.
Which is the best answer?
(a) the plate should be disgarded
(b) there were 5.8x10⁶ cfu/mL in the original
(c) there were 5.8x10⁷ cfu/mL in the original
(d) there were 7x10⁷ cfu/mL in the original A 13. Swabbings and subsequent plating of a 15-second-old neonate's skin were done. Which of the following plates indicates the baby's skin was probably sterile at birth?

(a) A + B
(b) C + D
(c) A only
(d) C only
A: of course, as there are no colonies (unless there was inept transfer technique)
B: the mere 2 colonies are probably from handling
C: just too many to have gotten there by handling - unless handlers were inept. This question was graded very loosely.
B 7. Jimmy made a 10-fold serial dilution and plated 10μL samples on a plate she labeled "J-3." The next day she obtained these counts in her four lanes:
TMTC, 82, 6, 1.
(a) the plate should be disgarded
(b) there were 8.2x10⁷ cfu/mL in the original
(c) there were 8.2x10⁶ cfu/mL in the original
(d) there were 6x10⁷ cfu/mL in the original E 14. Suppose in Plate C (previous question), you exhaustively characterized each of the dozen colonies on that plate and found that there were ten different types of bacteria present. This would mean:
(a) that the fetal skin was probably born sterile
(b) that the fetal skin had that many different kinds of bacteria on it
(c) that the delivery techniques were not very aseptic
(d) the bacteria were most likely environmental
(e) you can't tell
Fetal inoculation would unlikely be by many different strains, yet it is a possibility. Or maybe it was by poor infection-control handling. The jury is still out: need more evidence. This question was graded very loosely.

E	1. Bakers yeast is (a) a type of bacterium (b) a prokaryote containing both DNA and RNA (c) incapable of growing independent of a host cell (d) b and c only (e) none of the above Yeast is a fungus and thus eukaryotic. Used in levening bread, it obviously doesn't need host cells in which to grow.	E	8. Consider: (A) Streptococcus lactis, (B) Salmonella typhimurium and (C) Candida albicans. Which have any plausibilty for being "probiotic"? (a) A + B + C (b) A + B (c) A + C (d) B + C (e) only one of the species (f) none of them A is a dairy bacterium B causes mouse typhoid and human trots C causes trench mouth and vaginitis
C	2. Bakers yeast (a) causes vaginitis (b) possesses a cell wall, nucleus, chloroplasts and cytoplasm (c) can be stained with methylene blue to increase microscopic contrast (d) is in the Kingdom "Planta." (e) all of the above (f) none of the above It might cause vaginitis in immunocompromised people (e.g.: with AIDS). Doesn't have chloroplasts; Fungi, not Planta.	A	9. Honey expt: which horizontal row of disks exhibits a temperature of inactivation? (numbers on disks indicate subjecting the honey to that temmperature for 15 minutes and these were placed on a freshly seeded lawn of susceptible bacteria and then incubated overnight) All 20's disks are controls and should have halos, but only A does.
C	3. Bacteria and viruses: (a) both always contain DNA (b) both can be revived from the "dead" state (c) neither has mitochondria (d) all of the above (e) only a and c (f) none of the above Not A because RNA-viruses exist. Prokaryotes have no organelles: not nuclei, nor mitochondria...	D	10. Honey expt: Which horizontal set of disks indicate that the antibacterial agent is NOT a protein. Similar setup as with the previous question except that the treatments are different: "M" = meat tenderizer (papaine); "P" = pepsin; "B" = both B and C don't make sense as the "both" disks should have halos if one or the other or both the M and P have a halo.
E	4. The US Dept of Health and Human Services contains (a) the National Institutes of Health (b) The Food and Drug Administration (c) The Centers for Disease Control and Prevention (d) The Consumer Protection Agency (e) only two of the above FDA is a subdivision of the Dept. Agriculture CPA	B	11. Honey expt: Mary Lou dialyzed her honey, which resulted in (a) her dialysis "sausage" shriveling to near nothing (b) her "sausage" osmotically exploded (c) her "sausage" didn't change in volume You are all part of a team and should know what the others are doing! You saw the dialysis tubing enlarge as it hung in the flowing water at the sink for several hours. If it hadn't been removed, it would have exploded.
B	5. Considering the tiers in the pyramid of life, (a) the mass of all plants is greater than the mass of any other tier (b) the greatest bulk of all actively growing cells is mostly that of microöorganisms (c) in the food chain, animals eat the plants, which eat the fungi, which eat the bacteria (d) only plants are photosynthetic and thus the source of fixed-carbon supporting all other tiers of life (e) all of the above (f) only two of the above, but not e not C: plants eat sunlight and minerals but not fungi; not D: some bacteria photosynthesize (remember Beggiatoa from the previous week's ML quiz!	B	12. Honey expt: Cheryl's dialysis "sausage" was at first dialyzed against water, and then excess water was reverse-osmosed from the "sausage" such that the volume became equal to that of the honey she originally used. This was then "disked" and set on fresh lawns of bacteria. Which horizontal set indicates the antibacterial agent was a small molecule? (H = raw honey control; D = dialyzed) Not A or C as the H (control) didn't have halos. Not D because agent didn't diffuse away through the tubing.
C	6. Cheryl made a 10-fold serial dilution and plated 10μL samples on a plate she labeled "C-2." The next day she obtained these counts in her four lanes: TMTC, TMTC, 58, 7. Which is the best answer? (a) the plate should be disgarded (b) there were 5.8x10⁶ cfu/mL in the original (c) there were 5.8x10⁷ cfu/mL in the original (d) there were 7x10⁷ cfu/mL in the original	A	13. Swabbings and subsequent plating of a 15-second-old neonate's skin were done. Which of the following plates indicates the baby's skin was probably sterile at birth? (a) A + B (b) C + D (c) A only (d) C only A: of course, as there are no colonies (unless there was inept transfer technique) B: the mere 2 colonies are probably from handling C: just too many to have gotten there by handling - unless handlers were inept. This question was graded very loosely.
B	7. Jimmy made a 10-fold serial dilution and plated 10μL samples on a plate she labeled "J-3." The next day she obtained these counts in her four lanes: TMTC, 82, 6, 1. (a) the plate should be disgarded (b) there were 8.2x10⁷ cfu/mL in the original (c) there were 8.2x10⁶ cfu/mL in the original (d) there were 6x10⁷ cfu/mL in the original	E	14. Suppose in Plate C (previous question), you exhaustively characterized each of the dozen colonies on that plate and found that there were ten different types of bacteria present. This would mean: (a) that the fetal skin was probably born sterile (b) that the fetal skin had that many different kinds of bacteria on it (c) that the delivery techniques were not very aseptic (d) the bacteria were most likely environmental (e) you can't tell Fetal inoculation would unlikely be by many different strains, yet it is a possibility. Or maybe it was by poor infection-control handling. The jury is still out: need more evidence. This question was graded very loosely.