Friday, October 22, 2004 , 7:20 PM
><))o> The As has came! So has my doom!!!
#6 days to A level Chemistry Practical Examination
#13 days to A level General Paper Examination
#Wow! Look at the dates!!! The core papers for A level is creeping near!!! How scarey!! I went through a very terrible session of Biology Practical on Thursday...
#After scanning through the papers, i decided to attempt the second question regarding effect of the wavelenght of light on the rate of photosynthesis using DCPIP (an oxidising agent with itself being reduced during photosynthesis) ...my choice of the first question to attempt proved to be a bad one - a very bad one indeed! First of all, we were told mash up pieces of leaves given in a cold buffer to produce a green leaf extract. Next, we have to add 5 drops of DCPIP (which were blue initially) to the leaf extract, ensuring at the same time that we do not expose the mixture to light for too long. This means that we have to rapidly remove and replace the aluminium foil over the extract! How irritating!! This experiment is really not for clumsy and panicky people like me!! Anyway...the mixture i got was dark green...pretty much difficult to tell if the DCPIP inside was being reduced over time or not (after complete reduction, the mixture would turn back to the original colour of the leaf extract which was light green). There were 5 capillary tubes containing the mixture- the colour standard, a tube completely exposed to light, a tube completely wrapped in aluminium foil, a tube placed under a green fliter and another under a red fliter.
#Over my 16 minutes of observation (yes...16 mins!! Its that long!) I squinted and squinted to try to make out if any changes happened...eventually, my results tell me that DCPIP in the tube under the red fliter was being reduced the faster meaning photosynthesis occured at a faster rate followed by the tube that was fully exposed to light, then the tube under the green fliter and lastly, the tube that was wrapped in aluminium foil.
#I hate to say this...but 2 years of physics in secondary school has taught me nothing! Or rather, i learnt nothing! I can't recall if the filter was supposed to filter all the other spectrum of light except the colour of the filter itself or let all the other spectrum of light through except for the colour of the filter itself. Now, that point is kinda crucial for the explanation part...but...
I JUST COULDN'T RECALL! Oh well...i went along with my results and tried to make some sense of it! Hopefully its correct!
#After the horrifying question, i flipped the pages only to realise (to my horror again by the way) that there were at least 3 more sub parts to the question (what the O*^Y@(#) and one of it was a design experiment with 9 marks attached to it! I'm not a wimp or anything...but design experiments just freak me out (during O level physic practical, i left an entire design experiment out...and of course...subsequently how i got a B3 was a mystery...)
#After freaking out, i went on to the last question only to suffer mental block....it was a genetics question...i have absolutely no idea what the question was asking me! Feeling rather demoralised, i completed part of the question involving a chi-square test. (After the exam, i found out that if i had been more calm...i would have been able to read the genetics question in more detail and would have easily scored the marks! Oh...what a failure i am!) Went on with the first question which asked for plan and detailed drawings of kidney...relatively easy question i should say...then i did my design experiment which i later found out that was managable....=)
#The bio prac shocked everyone...having religiously mugged thru the past year practicals from the tys, the DCPIP question was really one of its kind...never in the history of bio practice has this experiment came out!! What the
*#@$^(! Oh well...but its over...i'm happy at least that i didn't really screw up the experiment...or at least i hopped! =) Hope chemistry prac won't be such a killer!
-if i die (in bio prac), i'm sure many others will die with me...so what's there to fear?-
