NBME 6 , step 1 (with Answers)-Tahsin

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BLOCK 3



















"STREAKING": is is a technique used to inoculate organism on agar plate.For this we use cotton swab or "Inoculant WIRE Loop" which is a wire that have
very small loop at it's tip.

At first we sterilize and then dip this loop into sample that we have collected.Now we roll it on 1/4th of the agar plate(Just like u see in stem pic the
region marked with "A").
Second Next we sterilize the loop again and this time we don't dip it in the collected sample rather we drag it over the FIRST 1/4th inoculated region
which will pick up the organisms and spread it to the next 1/4th space on the agar plate.
Third Next we sterilize the loop again and this time we drag it over the SECOND 1/4th inoculated region which will pick up organisms and spread it to the
next 1/4th space on the agar plate.
Fourth Next we reapeat the same previous step to spread on the last 1/4th space on the agar.
** Every time we repeat the streaking it picks up fewer and fewer organisms and in the end we end-up separating the "PURE COLONY OF SINGLE
ORGANISM" as u see the colony that is marked with "D".Now in our second step of streaking we got Gray and White colonies but not the black one and
again in the third step we just got Gray colonies which means the black one was not present at all in 2nd and 3rd 1/4th region of agar but showed up
on the fourth step that tell us that it was contaminated as is also present in the first 1/4th streaked space.
http://video.google.com/videoplay?do...3448873922892#









Is it because Ethanol is going to increase the Acetate which enters the TCA cycle and >> the ratio of
NADH:NAD and to compensate for the >>NADH , Pyruvate will be reduced to lactate..is this the mechanism
of Hypoglycemia in this patient??













No.4. B. q square = 1/2500, so q = 1/50, therefore
2pq=2x1/50 = 1/25