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can some one help me in Q15 
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AS Biology P1 MCQs Preparation Thread
- Thread starter Soldier313
- Start date
http://www.xtremepapers.com/papers/...nd AS Level/Biology (9700)/9700_w11_qp_12.pdf
28) how do we know which 1 is xylem and which 1 is phloem?
22) how do we know which one is 3 and 4. One has 3 hydrogen bonds lines and the other has 2 hydrogen bonds lines but what do they mean?
28) how do we know which 1 is xylem and which 1 is phloem?
22) how do we know which one is 3 and 4. One has 3 hydrogen bonds lines and the other has 2 hydrogen bonds lines but what do they mean?
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- Messages
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22) 3 h-bonds means, bond between Guanine and cytosine, 2 h-bonds means, bond between adenine and thymine
Its xylem. The element is vessel and tissue it belongs to is xylem so the correct option is D. This can be deduced from the absence of any cross/end walls in the element and the presence of spots which indicate pits (that are only found in xylem.)
For 22) one can clearly identify 2 as phosphate and 1 as deoxyribose sugar, eliminating options A and D. To identify 3 and 4, the hydrogen bonds may be accounted for. There are always 3 hydrogen bonds between guanine and cytosine and 2 hydrogen bonds between adenine and thymine/uracil. Therefore, the correct option is C and not B.
Primary Structure= Peptide Bonds
Secondary Structure= Hydrogen Bonds
Tertiary and Quaternary = Di-sulfide linkage, Ionic bonds and Hydrogen bonds Also Hydrophobic interactions)
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but when the protein is in tertiary, isn't it includes primary and secondary? Hence, it has peptide bonds?
No when they ask about separate levels we never mention the other structures.
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http://www.xtremepapers.com/papers/CIE/Cambridge International A and AS Level/Biology (9700)/9700_w03_qp_1.pdf
http://www.xtremepapers.com/papers/CIE/Cambridge International A and AS Level/Biology (9700)/9700_w03_er.pdf
Q 28, 32 & 35 Someone explain these questions?
http://www.xtremepapers.com/papers/...and AS Level/Biology (9700)/9700_w05_qp_1.pdf
http://www.xtremepapers.com/papers/...A and AS Level/Biology (9700)/9700_w05_er.pdf
Q3 Is a lysosome always bigger than a ribosome? cuz i thought they were smaller hence i answered D which is wrong.
Q5 A phagocyte depends on lysosomes in which there are enzymes for digesting pathogens but doesnt a goblet cell need a larger number of lysosomes in which it secretes mucus?
Q17 Is lysis the same plasmolysis or something different? And why cant the answer be C?
Q30, 38 and 39 please also explain them.
http://www.xtremepapers.com/papers/CIE/Cambridge International A and AS Level/Biology (9700)/9700_w03_er.pdf
Q 28, 32 & 35 Someone explain these questions?
http://www.xtremepapers.com/papers/...and AS Level/Biology (9700)/9700_w05_qp_1.pdf
http://www.xtremepapers.com/papers/...A and AS Level/Biology (9700)/9700_w05_er.pdf
Q3 Is a lysosome always bigger than a ribosome? cuz i thought they were smaller hence i answered D which is wrong.
Q5 A phagocyte depends on lysosomes in which there are enzymes for digesting pathogens but doesnt a goblet cell need a larger number of lysosomes in which it secretes mucus?
Q17 Is lysis the same plasmolysis or something different? And why cant the answer be C?
Q30, 38 and 39 please also explain them.
Primary:
The types and sequence in amino acids are arranged. Bonds present are pep-tide bonds.
Secondary:
The coiling of the structure to form alpha helix. Bonds present are Hydrogen bonds.
Tertiary:
The way in which bonds are arranged to give a 3-Dimensional structure. Bonds present are Disulfide bond, Ionic bond, Hydrogen bonds and Hydrophobic interactions
Quaternary:
Presence of more than 1 polypeptide chain. All the bonds present in tertiary structure.
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O/N3:
Q.28 This question has no relation with our syllabus but the logic behind it is that when they said average requirement, emphasis on average, it meant 50%.
Q.32 A person who seems fit is the one who's rise in pulse is very slow and resting time(period after exercise) is low i.e rapid decrease in pulse to return to normal.
Q.35 The bacterium cholera cannot be treated with vaccination as well as HIV/aids. Malaria has many genes due to genetic complexity of plasmodium. Tb can be treated with the BCg vaccine to provide immunity.
O/N05:
Q.3 No the smallest of them is ribosome having width in nano-meters. An easy way to remember is NCMLR(nucleus,chloroplast, mitochondria, lysosome and ribosome)
Q.5 Your confusing with exocytic vesicles. Lysosome have large amount of hyrolytic enzymes used by phagocytes. Goblet cells secrete mucus which largely depends on secretory vesicles.
Q. 17 Yes lysis is the same the thing. Why facilliated diffusion? We don't know whether haemoglobin is polar or not. Don't confuse youself with that.
Anyways it was placed in water.
Q.30 First of all its the lower graph as they said an actively respiring in which CO2 is being respired so a lower pH is low. If move from B to D. Oxygen is being taken up and If we move from D to B, oxygen is being released to the actively respiring cells.
Q.38 It can't be A as they said Mosquitoes not Plasmodium. B is wrong as antigens are detectable but as C says the plasmodium hides inside Liver and red blood cells also known as antigenic concealment. D is just rubbish
Q.39 I'll give you my own example. 1,000 kj energy is being supplied by the sun. 980 of it is reflected, not absorbed blah blah. Only 20 Kj is left of which is used by cell and some is lost so energy transfer is low. From plant to other species the energy tranfer is always 10% which is higher than the enrgy transfer b/w sun and plant. Remember they are talking about the efficiency not the amount of energy transfer.
Hope I helped you!
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guyz check out qs 22. I am pity sure the mark scheme is wrong!
How can 1 be cytosine??
http://www.xtremepapers.com/papers/...nd AS Level/Biology (9700)/9700_w11_qp_12.pdf
http://www.xtremepapers.com/papers/...nd AS Level/Physics (9702)/9702_w11_ms_12.pdf
How can 1 be cytosine??
http://www.xtremepapers.com/papers/...nd AS Level/Biology (9700)/9700_w11_qp_12.pdf
http://www.xtremepapers.com/papers/...nd AS Level/Physics (9702)/9702_w11_ms_12.pdf
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the answer is C.
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the mark scheme is physic! Hahaha
http://www.xtremepapers.com/papers/...nd AS Level/Biology (9700)/9700_w11_ms_12.pdf
The mark scheme is for physics! biology is 9700, not 9702 (the mark scheme)
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