IMAT 2019 Q32 Biology Beetroot Q

I was wondering if anyone had the same ideas as me while solving this question.

  • In 20 degrees C water, both P Q should not turn red or denature protein and dissolve phospholipid. So eliminate row 1, 4, and 5.
  • Lipids readily dissolve in ethanol allowing phospholipids to dissolve - turning liquid P red
  • Dilute HCl denature protein by creating an acidic environment - turning liquid P red
    Therefore the answer is E, row 3.

I did look to see if row 2 could be an answer as well but haven’t gotten any clear answers yet if anyone can tell me why it can’t be an answer that would be greatly appreciated.

Do you have the main question from the test?

Sorry - didn’t know how to crop pictures on macbook but here it is

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Hey, just checked the answer sheet and E is correct :slight_smile: :+1:t2:

thanks for that but I was wondering if anyone came to the same conclusion according to how I solved the problem

I did, I think the logic checks out, though admittedly when I answered it I went straight for the dilute HCl denaturing protein for liquid Q so got to row 3 straight away

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Ethanol can make hydrogen bonds with the fatty acids of the phospholipids and dissolve the bilayer of the membrane. Dilute HCl is not capable of that due to its low concentration i.e. inadequate interacting ions in the solution to completely break op the intermolecular forces between the lengthy fatty acids chains of the phospholipids.

HCl can break hydrogen bonds and disulfid bonds on proteins and denature the integral proteins of the membrane which act as channels. Channels (which are selective passages) will then get opened or damaged. On the contrary, treatment of polypeptide chains with ethanol promotes formation of sulfhydryl and disulfide bonds.

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