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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?
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alisha said: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?
alisha said: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?
bionology said:alisha said: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?
RBCs don't have a nucleus - no DNA means no code for proteins (enzymes are proteins!). Replication and all that can't take place either. And there's no RER for protein synthesis and transport.
bionology said:RBCs don't have a nucleus - no DNA means no code for proteins (enzymes are proteins!). Replication and all that can't take place either. And there's no RER for protein synthesis and transport.
i just misunderstood this one, i wrote that enzymes have active sites, rbc's don't and so thay can't replace them and perform their function
sakibfaiyaz said: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.
bionology said: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
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