Biology P22 Was Quiet Easy !!!!

[hassam]

well guyx y dont u referred to initially decrease in ph very steep later on it was less steep.....m sure there will be a mark for this.....

 

[Anonymousx3]

At first I wrote that all the enzyme active sites are full, and they're working at their max. rate (since there was more oil than enzyme) but then I changed it and said that substrate concentration becomes limiting - no more triglycerides are being converted, so the pH remains constant.

 

[hassam]

ya this ryt.....theres a similar question in o/n 05 ....and there when graph levels off it says reaction complete not DENATURING

 

[filza94]

yeah now get dix ovr study physics okay!!!!

 

[boy2011]

well see that questns basicaly focuses on enzyme u see the first part they askd dat y ph8 is used nd v wrote its da optimum ph for lipase so obviously below ths ph enzyme's active sites goin to get denatured..well lets hope for gud...

 

[filza94]

ufffff i have to tel mods to lock dix !!!!

 

[boy2011]

filza y u wl tel mods to lock it?if u dnt wana see da answer dnt visit ths forum

 

[filza94]

i dont want n itx my post well itx riten by me so i want it to be locked make ur new post n dicuess there!!!!

 

[boy2011]

huh u make ths post to discus the paper any ways go do wateva u want

 

[Jaguar47]

Yup Yupp..dee paper was Cream :Yahoo!: ...i waz surprised n' wondering: "maybe CIE ran out of questions to make" - Lolzz...bUT i'm doubtful about the streptomycin one !
Only the chapters that i studied Last Night Came.. Alhamdulillah !.. The ones that i was worried about (e.g Immunity) n' the ones that i didnt know didn't come..- PRAISE BE TO OUR LORD !

Watch this vid GuYz..I'm sure you'll like it !
http://www.youtube.com/watch?v=6ZXOMUuv97M
O ALLAH, THERE IS NO EASE EXCEPT WHAT YOU MAKE EASY !
AND YOU MAKE THE DIFFICULT EASY, IF YOU WISH !

They definitely did not run out of questions, Bio 21 wasn't that easy. Glad you guys found the 22 easy though

 

[BILALrox01]

well the ph was constant at 7, for that i wrote the substrate has finished. So no more enzyme reaction takes place and the ph is constant

for resting stage, yes DNA and the centrioles are replicating, so the cell is not in rest stage, the processes are going on



P.s, I dont the think so the paper was so easy. Have you ever read the mar schemes? they have very specific answers for their questions, and if you do not touch their criteria, they simply don't award u marks.
I must say that it was technical

PH was not at 7 when it becomes constant it was like 6.sumthing soo i thnk enzyme got denatured as lipase works best in slightly alkaline conditions...

I wrote both denaturation and Substrate concentration

 

[alisha]

oki its been 24hrs rite....those cells in the first question were small coz they were gaurd cells? and how about the question on how the ribosome activity is inhibited?

I said they were small 'cause they've just divided (gone through cytokinesis) so they've yet to go through interphase, which is where the cells grow to their proper size.

But I think I wrote prophase when I was meant to write interphase - ugh. D;

oh great! then im losin a mark. i thought they wr gaurd cells coz thr was a gap in between and i thought they wr the stomata!

 

[alisha]

oki its been 24hrs rite....those cells in the first question were small coz they were gaurd cells? and how about the question on how the ribosome activity is inhibited?

eh....what? guard cells? in between? I doubt that.
I wrote might be because the mitosis has finished or not yet started. I guess both would be acceptable because every cell was in a different stage of mitosis

1 got my 1 point wrong from ribosomes but for the second i gave reference to non-competitive inhibition

what was the answer for the stupid red blood cell replacing the enzyme? why can't it?

i gave one point in competitive inhibition ( binds to the site at which mRNA binds to, and the next i also gave non competitive inhibition.

 

[alisha]

Hey please tell me if my answers are right.
For Question 1(ii) i wrote: Because they have might not have begun with their new cell cycle, i.e they are still young in their life stages.

for (iii) I wrote: They are not in a "resting" stage because here they undergo DNA replication in the S stage of interphase and other synthetic reactions in G1 and G2 of interphase.

For the question about RBCs' inability to make new proteins, I wrote: Because they lack nucleus,ribosomes and ER-hence no protein synthesis. And they do not have Golgi apparatus so inevitably no final processing and packaging which are but essential to such globular proteins.
Hydrolysis of globins give AMINO ACIDS right? :S

For the question "why doesn't streptomycin affect mammals", I wrote: Because they affect 70s ribosomes not 80s as in eukaryotes.
I am very confused about the enzyme question, for the 4 mark question I wrote : Because lipase catalyses breakdown of triglycerides to glyerol and fatty acids. Fatty acids lower the pH. Since lipase works best in alkaline conditions, as the reaction proceeds the pH decreases, ionic bonds holding the tertiary structure break and it becomes increasingly unfavourable for lipase until when t=50 mins and the enzyme denatures completely.

ya i wrote pretty much the same, but for the reason why the antibiotic does not affect mammal cells i wrote coz they have antibodies that are specific to the antigens on the pathogen. i think im wrong

 

[workinghard]

oh alisha i think dats a valid point since dey R specific n bacteria structure IS diff!
n aquariangurl i wrote dat cux u no dere IS an optimum ph below or above which da enxyme wont work.... u think i m losing a mark... plx say NO!!!

 

[alisha]

ya thats what i also thought when writing the answer but im not sure if it is right.

 

[alisha]

well see that questns basicaly focuses on enzyme u see the first part they askd dat y ph8 is used nd v wrote its da optimum ph for lipase so obviously below ths ph enzyme's active sites goin to get denatured..well lets hope for gud...

i wrote all the reasons i could think of. about the enzyme getting denatured and because all the triglycerides get converted so the number of fatty acids will be constant. so i hope they gimme a mark for whichever answer is correct! or do you think they wont give me ANY mark?

 

[filza94]

i rote because the enzyme is denatured!!!!

 

[oohlala]

isnt it that the ph decreases coz oil was hydrolysed to fatty acids which lower the ph value??
i did'nt write anything about active sites or concentration of substrate :no: :fool:

 

[boy2011]

alisha it depends on the examiner..bt i thnk ul get the mark