AS Biology P1 MCQs Preparation Thread

[Soulgamer]

Why can't the answer be phospholipid?

I think I already answered that.

 

[Soulgamer]

Increasing unsaturated hydrocarbons increase fluidity i.e. Unsaturated tails fit in more loosely. Hence the answer is C i guess?
Hydrogen bonds have no use here.

 

[Soulgamer]

Why can't the answer be phospholipid?

Check my latest post. I answered that, somebody had the same question.

 

[xyz!]

Why can't the answer be phospholipid?

is the answer cholestrol?
n according to me it cant be phospholipid bcos the hydrophilic heads of the phospholipid bilayer form hydrogen bonds with water molecules and thus help maintaining the membrane's stability in watery surroundings and not fluidity!

 

[rogue94]

Why can't the answer be phospholipid?

phospholipids make the membrane less fluid or more fluid, but cholestrol regulates the fluidity and makes the membrane more flexible. Saturated or unsaturated hydrocarbon tails of the phospholipids determine the fluidity of the membrane, whereas cholestrols control that fluidity (prevent too much fluidity or too much rigidness.)

 

[JulyMei]

phospholipids make the membrane less fluid or more fluid, but cholestrol regulates the fluidity and makes the membrane more flexible. Saturated or unsaturated hydrocarbon tails of the phospholipids determine the fluidity of the membrane, whereas cholestrols control that fluidity (prevent too much fluidity or too much rigidness.)

ok.. thx.. this fluidity thing is freaking me out now.

 

[Nibz]

can some one help me in Q15

What's so difficult in this one?
In 0.1 moldm^-3 solution the change of length is positive, clearly showing that the sucrose solution has MORE water potential than the inside of cells. The more the water potential, the less negative the value will be.
Option C: "The water potential of the sucrose solution was less negative (i.e it had more water potential) than the water potential inside the cells.

 

[hmlahori]

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!

That was a lot of help thanks! Just one more question. for Q 17 the one about movement of haemoglobin. still dont get why it is lysis. So the rbcs are placed in a solution with higher water potential than them. water will move in by osmosis. so the cell will become turgid. as haemoglobin is not present in the solution it will move out down a concentration gradient by diffusion, no?

 

[confused123]

http://www.xtremepapers.com/papers/CIE/Cambridge International A and AS Level/Biology (9700)/9700_s05_qp_1.pdf
8, 18, 35 ( why not odr options..?) , 37, 38 why not B?

anyone?

 

[SalamH]

anyone?

8) ans is B coz btwn p-q, 1-6 glycosidic bond forms n btwnq-w, 1-4 glycosidic bond forms
A- p-u is rite but p-v is wrong coz there is no bond formed btwn carbon2 n carbon6
C-p-v wrong (reason above)
D-p-w, there is no condensation btwn c4 and c6 and v-w wrong coz condensation can't take place within 1 molecule
there r 2 types of bonds in carbohydrates.1-4 glycosidic bond(btwn c1 and c6) and 1-6 glycosidic bond (btwncarbon 1 and 6)
18)ans is B coz active transport means against conc gradient (from low conc to high conc)
Na+,conc in cell is 15 and out it is 144, so low inside and high out so it moves out
K+,inside cell its high(150) and out its low(5) so it moves in
Cl-,inside low coz 73 and outside high coz 111 so it moves out
37)ans is D not B coz B cells remain in the bone marrow until they r mature and then spread throughout the body concentrating in lymph nodes and spleen.T lymphocytes leave d bonemarrow n collect in d thymus where they mature then they circulate btwn blood and lymph
hope you understand
sorry I dunno 35 and 38

 

[Ineedhelp]

For the 1st question the answer is C (144). The working is: 12^2 = 144. Here 12 is the no. of different amino acids and 2 is the no. of amino acids in the chain (its a dipeptide so, 2 amino acids).
For question 4 the answer is C. Lysosomes contain most of the hydrolytic enzymes as it is their function to digest/break down, a wide variety of substances (such as organelles and bacteria).

Thankyou! =D

 

[Oliveme]

m havng a few doubts in 9700/11/O/N/11.... Q5, Q14, Q20, Q24, Q28, Q29, Q30, Q36 AND Q40
pls post explanations/solutions for these questions
here's the link for the ppr and the ms....
paper==> http://www.xtremepapers.com/papers/CIE/Cambridge International A and AS Level/Biology (9700)/9700_w11_qp_11.pdf
ms==> http://www.xtremepapers.com/papers/CIE/Cambridge International A and AS Level/Biology (9700)/9700_w11_ms_11.pdf
thnx!

5) one whole stage micrometer is 0.1 mm and this length occupies 40 divisions on the graticule so one small division on the eye piece graticule is 0.1mm/40 = 0.0025 mm that is 2.5 micrometers. the nucleus, you'll see occupies approx 10 divisions. so 2.5 x 10 divisions = 25 micrometers.
sorry can't help with the others.

 

[Oliveme]

http://www.xtremepapers.com/papers/...nd AS Level/Biology (9700)/9700_w11_qp_11.pdf
http://www.xtremepapers.com/papers/...nd AS Level/Biology (9700)/9700_w11_ms_11.pdf
please explain these questions to me ----> 20 and 24. thank you very much.

 

[HuN3yy !!]

http://www.xtremepapers.com/papers/...and AS Level/Biology (9700)/9700_w05_qp_1.pdf
Anyone plzz Help me ..em confused in qst no 11, 24 and 27 !!! plz do help

 

[Knight]

http://www.xtremepapers.com/papers/...nd AS Level/Biology (9700)/9700_w10_qp_12.pdf
Q; 9, 17, 18..........plz help

 

[Jaf]

http://www.xtremepapers.com/papers/CIE/Cambridge International A and AS Level/Biology (9700)/9700_w10_qp_12.pdf
Q; 9, 17, 18..........plz help

In 9th, Option D has no carbons which can attach to another carbon in the molecule (all the carbons have octet configurations in terms of chemistry)

In 17th, mitosis only helps in cell division. It doesn't help in the growth (increase in size) of the cell. Hence it's B. Just to make it clear, option C 'increase in size' refers to the increase in size of a multicellular organism and not individual cells.

In 18th, plant cells do not have centrioles. B and C can eliminated. The diploid number can't possibly be 4 since there are clearly 8 chromosomes visible.

anyone?

8 - Glycosidic bonds between glucose molecules, in glycogen, are only of the type 1, 4 and 1, 6.
s and w are the 4th carbons, p and t are the 6th carbons and q and u are the first carbons in the first and second molecules respectively. So B is the answer.

18 - Troll question. I remember I got it wrong the first time I did it too.
Notice the question mentions 'actively transported'. This means that the conc. of the substance being transported has to be less wherever it if going (in/out of cell). Only in B are the substances moving against their concentration gradients.

35 - This is weird. I could have sworn the answer for this question was D. It's C. I'm really not sure why.
Nonetheless, take the easy way and cross out all the options the biology of which we haven't studied. No allergies and no bacteria in the gut. B can't possibly it because human cells (unless it's an allergy) don't respond to antibiotics.

37 - D. T-lymphocytes are the only cells from the given options that mature in the thymus gland.

38 - A. All other options will restore nitrogen compounds to the soil.

http://www.xtremepapers.com/papers/CIE/Cambridge International A and AS Level/Biology (9700)/9700_w11_qp_11.pdf
http://www.xtremepapers.com/papers/CIE/Cambridge International A and AS Level/Biology (9700)/9700_w11_ms_11.pdf
please explain these questions to me ----> 20 and 24. thank you very much.

20 - a piece of double-stranded DNA is being taken with 6000 nucleotides. Since only the sense strand is transcribed, 3000 nucleotides (all the nucleotides on one strand) are used for transcription. This will give an mRNA strand 3000 nucleotides long. A tRNA, that has an anti-codon with 3 nucleotides, carries one amino acid. So 3000/3 = 1000 amino acids.

24 -
1 - AV valves close 2 - SL valves open 3 - SL valves close 4 - AV valves open
So time between 1 and 2 and, 3 and 4 is when both valves are closed. This'll be C 0.07 approximately.

http://www.xtremepapers.com/papers/CIE/Cambridge International A and AS Level/Biology (9700)/9700_w05_qp_1.pdf
Anyone plzz Help me ..em confused in qst no 11, 24 and 27 !!! plz do help

11) The order of increasing conc. of reducing sugar for Benedict's test is:
blue ---> green ----> yellow ----> orange -----> brick red
Only A satisfies this.

24) 3 seems to be an RNA molecule since it contains uracil and lacks thymine. So we know C is thymine. Now we need to compare which base has similar proportions to B in 1, 2 and 4 to determine which one is adenine (since A pairs up with T). This is true for B.

27) The plant will try to close the stomata when the conditions around the leaves are dry and little water is available to the plant. This is true for D only.

Hope all this helps.

 

[JulyMei]

In term of size, is nucleolus bigger or ribosome bigger?

and.. what is the size of a starch grain?

 

[Jaf]

In term of size, is nucleolus bigger or ribosome bigger?

Obviously, nucleolus. This is because the ribosomes are made inside the nucleolus.

and.. what is the size of a starch grain?

There's no real fixed size. They can be big or small. But they're pretty conspicuous structures inside chloroplasts.

 

[JulyMei]

Obviously, nucleolus. This is because the ribosomes are made inside the nucleolus.


There's no real fixed size. They can be big or small. But they're pretty conspicuous structures inside chloroplasts.

thanks!!!
Cuz i found one of the website saying nucleolus is smaller than ribosome.. so i was confuse with it..

 

[JulyMei]

Why it's 5? and not 3?

When they said air in alveolus isn't it that, to reach RBC, air from alveolus goes out of the alveolar wall, goes into endothelial wall, goes into RBC???



What does reduction division means? why can't it be T and V?