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A level Biology: Post your doubts here!
- Thread starter XPFMember
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Because its affinity for oxygen does NOT change with altitude.
the affinity itself remains the same. The curve we study is of the percentage SATURATION of haemoglobin with oxygen against partial pressure of oxygen (the s shaped curve) and it remains the same. What changes is the percentage of haemoglobin that is saturated with oxygen, not the ability of haemoglobin to bind with oxygen since that is represented by the curve itself and the curve remains the same. The only thing that changes the affinity is the carbon dioxide which shifts the entire curve toward the right, THAT is a change in affinity (the Bohr effect or shift). I hope this makes sense. - Messages
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Thank you so muchBecause its affinity for oxygen does NOT change with altitude.
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What abt the other one
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Very good question. There are two ways to go about it. One way, which I don't recommend, is remembering that cholesterol is not found on the outer surface. You can infer that from the fact that in our books' diagrams, they never show cholesterol in the outer membrance of the cell surface membrane. It's always in the side facing the cell contents (the inner membrane), not the outer side. However, you cannot be expected to know, because this way, you can never be sure about how much information you need to cram in your head. The smart and intelligent way to solve this question is to use the elimination method for MCQs. Begin by looking at each option and first get rid of the ones that you know are wrong. You should and would know for certain the phospholipids ARE found in both the outer and inner membranes because we study explicitly that cell membranes are made of a 'phospholipid bilayer', and this means that they are present in BOTH layers. So you can get rid of options A and C simply because they are utterly stupid by saying that phospholipids aren't found in the outer membrane. Now you have B vs. D. Here is where the smart decision comes into play. In our syllabus we are taught in more detail about glycolipids and glycoproteins (in this question they mention glycolipids). Our syllabus specifies that we need to know about cell signalling and cell recognition and how these parts play a role in this aspect. So, it makes logical sense that glycolipids SHOULD be found on the outer surface because they play a role in cell recognition. Obviously they can't play a role in that if they aren't on the outside. Thus, you get rid of B, leaving only D as the logical choice left. This way you can select the right option without even thinking about cholesterol. Hope this helps.
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it really didVery good question. There are two ways to go about it. One way, which I don't recommend, is remembering that cholesterol is not found on the outer surface. You can infer that from the fact that in our books' diagrams, they never show cholesterol in the outer membrance of the cell surface membrane. It's always in the side facing the cell contents (the inner membrane), not the outer side. However, you cannot be expected to know, because this way, you can never be sure about how much information you need to cram in your head. The smart and intelligent way to solve this question is to use the elimination method for MCQs. Begin by looking at each option and first get rid of the ones that you know are wrong. You should and would know for certain the phospholipids ARE found in both the outer and inner membranes because we study explicitly that cell membranes are made of a 'phospholipid bilayer', and this means that they are present in BOTH layers. So you can get rid of options A and C simply because they are utterly stupid by saying that phospholipids aren't found in the outer membrane. Now you have B vs. D. Here is where the smart decision comes into play. In our syllabus we are taught in more detail about glycolipids and glycoproteins (in this question they mention glycolipids). Our syllabus specifies that we need to know about cell signalling and cell recognition and how these parts play a role in this aspect. So, it makes logical sense that glycolipids SHOULD be found on the outer surface because they play a role in cell recognition. Obviously they can't play a role in that if they aren't on the outside. Thus, you get rid of B, leaving only D as the logical choice left. This way you can select the right option without even thinking about cholesterol. Hope this helps.
thank you so much
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Okay very interesting picture haven't seen anything like this before. o_o But let's see, you got the basic idea down and you seem to have decent drawing skills so be proud of that. The nucleus is perfect, no need to dot or anything. That's risky because dots if you ever draw them should be precisely dots and if your pencil manages to extend a dot even by the slightest amount it'll end up looking like a broken line or something and that's not cool. So always work with circles/blobs, of course, without shading or anything. A plan diagram is meant to highlight the different components, that's all. It's not supposed to be an accurate representation of the minor details. Think of it as the blueprint of a house. Other than that I think it's perfect I saw the mark scheme and it's all set. Just one thing, near the blue goblet cell you seem to have drawn a finer line outside it. I think you did that since you can't tell where to end it cause its secretions are all over the place. The mark scheme says that you should have at least 6 outer enclosed areas. That's probably a reference to the 3 nucleus + 3 cells = 6 outer enclosed areas. The goblet is probably up to your own discretion so only close it if you're really sure that you can see a boundary of some sort. Secondly, even if you do do it, then make sure it's as thick as the rest of the lines because why not? Cell membranes are cell membranes so why draw this one line so much fainter than the others? Finally there are some areas where you have some overlapping going on, I'll highlight them and reattach the picture. Finally, don't number the cells. I can see 1 2 and 3. Or if you did it for your sake then make sure it's erased properly.
I hope it helped.
Attachments
Thank you so much for your time. I'll be sure to correct the mistakes.Okay very interesting picture haven't seen anything like this before. o_o But let's see, you got the basic idea down and you seem to have decent drawing skills so be proud of that. The nucleus is perfect, no need to dot or anything. That's risky because dots if you ever draw them should be precisely dots and if your pencil manages to extend a dot even by the slightest amount it'll end up looking like a broken line or something and that's not cool. So always work with circles/blobs, of course, without shading or anything. A plan diagram is meant to highlight the different components, that's all. It's not supposed to be an accurate representation of the minor details. Think of it as the blueprint of a house. Other than that I think it's perfect I saw the mark scheme and it's all set. Just one thing, near the blue goblet cell you seem to have drawn a finer line outside it. I think you did that since you can't tell where to end it cause its secretions are all over the place. The mark scheme says that you should have at least 6 outer enclosed areas. That's probably a reference to the 3 nucleus + 3 cells = 6 outer enclosed areas. The goblet is probably up to your own discretion so only close it if you're really sure that you can see a boundary of some sort. Secondly, even if you do do it, then make sure it's as thick as the rest of the lines because why not? Cell membranes are cell membranes so why draw this one line so much fainter than the others? Finally there are some areas where you have some overlapping going on, I'll highlight them and reattach the picture. Finally, don't number the cells. I can see 1 2 and 3. Or if you did it for your sake then make sure it's erased properly.
I hope it helped.
Alright bro, it's easy game.
A base pair consists of 2 nucleotides.
Base pair bonds with hydrogen bonds - 2 for A-T and 3 for G-C
Number of base pairs for 700 nucleotides are 700/2=350.
Minimum number of hydrogen bonds(2) are 350*2=700
Maximum number of hydrogen bonds(3) are 350*3=1050
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Is 36,D and 22 , D.. or are the circled answers correct?
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Great job ur ans r correct but I'm confused y there is hydrogen bond with non polar molecule?
Hmmm interesting. I solved it by elimination, giving me last 2 options as closest possible. Maybe someone else can help here.. But as far as i know, water does not form H-bonds with non polar molecules...
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Water is attracted to lignin in the cell walls of Xylem vessels through 'Adhesion' which means it is attracted to lignin in cell walls of xylem vessels through hydrogen bonds with the help of their cohesive property. Lignin has both hydrophobic and hydrophilic groups in it. hope this helps!
"This process is known as mass flow - as long with the fact that water molecules move together as a body of water - aided by water's property of being cohesive, and attracted to the lignin in the walls of the xylem vessels, known as adhesion." from https://en.wikibooks.org/wiki/A-level_Biology/Transport/multicellular_plants