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Biology HL TZ2 Paper 1 and 2


ibinsouthafrica

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Thought paper 2 was much easier than past years....partially because I'm not a fan of human physiology or genetics and not too much of those topics were in the extended answers haha. I agree, paper 1 seemed to have a few trick questions....What did you guys put for the question about the number of cells undergoing metaphase in paper 1?

I counted 3 but you can never be sure with the stupid micrographs...

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I felt kind of frustrated with paper 2, though I know it was easy. They put in a lot of SL core material stuff that I skipped right over while studying. =/ I really thought they would ask more HL questions... oh well. And I did study for a month. HL biology was supposed to be my 7 =(

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Thought paper 2 was much easier than past years....partially because I'm not a fan of human physiology or genetics and not too much of those topics were in the extended answers haha. I agree, paper 1 seemed to have a few trick questions....What did you guys put for the question about the number of cells undergoing metaphase in paper 1?

^THIS^ Please! I've hear 3 is the supposed answer :/ :'( i put 7, i tried to look for a time when they were lined up... but i couldnt see anythang ...

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Thought paper 2 was much easier than past years....partially because I'm not a fan of human physiology or genetics and not too much of those topics were in the extended answers haha. I agree, paper 1 seemed to have a few trick questions....What did you guys put for the question about the number of cells undergoing metaphase in paper 1?

I think there were 3 cells, but I'm not certain.

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Was the actin one about where it was made? If it was that question I put free ribosomes as the answer (can't remember what letter that was).

II know that some (quite big) part of my classmate chose endoplasmic reticulum (proteins for exocytosis) but some (including me) chose sarcoplasmic reticulum. While one of the best students in our class picked rough endoplasmic reticulum pointing that actin is a fibrous protein so i has mainly secondary sturcture and does not need any further modification so it will be just synthesised and then exocitosised. Anyway I'm confused with this question...

I chose sarcoplasmic reticulum too cuz I think I read on ib.bioninja before that the muscle fibres have this layer called the sarcoplasmic reticulum instead of the endoplasmic reticulum

I thought that sarcoplasmic reticulum mainly functions in storage of calcium ions but it's a good point though.

I'm not 100% sure but I don't think the sacroplasmic reticulum carries out protein synthesis

I agree. And also, isn't is possible for other cells than muscle cells to produce actin for use within the muscle? Because in that case, endoplasmic reticulum sounds reasonable :hmmm:

Well, muscles cells are excpetion from the cell theory because they have multiple nuclei within one cell so I think it would be very difficult to synthesis such specific protein outsde the muscles. Plus the fact that actin is a monomere and undergoes polymerisation (normally it is globular protein but after polymerisation it becomes fibrous) after protein sythesis is quite an argument for sarcoplasmic reticulum.

i thought that precisely because its being synthesized IN the muscle, it means free ribosomes are producing actin so that it can stay in the sarcoplasm. plus the sarcoplasmic reticulum doesnt appear to have ribosomes? im so confused

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