AS Biology P1 MCQs Preparation Thread

[XPFMember]

aoa

this one too....why wont it alter the active site shape?

 

[Soldier313]

urgent help for this one pleeeeeeeaaaaaseeeee

 

[sarahnafea]

If it's not too late does anybody understand the relationship between the girth (circumference) of a tree trunk and the cohesion-tension theory? It seems to be a recent favorite amongst the examiners. Thanks

 

[Nibz]

aoa

this one too....why wont it alter the active site shape?

View attachment 12860

Because it binds to the 'Enzyme-substrate' complex where the active site has already been occupied.

 

[Jaf]

help needed!!!!!! question 34, 38 and 40 of oct/nov/13/2010

34, fIrst you need to see that in sample 3, when uracil is 25, C is nil, which means C is THYMINE because the two are never found together. Once you have found that C is Thymine, whichever base is the same/nearly the same as C is adenine because, due to base pairing specificity, the two have to be equal. If you check, B is nearly the same as C in all cases and, so, the answer is B.

38, you may check above. I asked the same question on he last page, as 39 on paper 11, check the answer provided for that.

40, for this you need to understand basic mathematics. By mutipling the number of individuals with the biomass per individual, you will get the total biomass of the species in the ecosystem. When you multiply this by the energy per unit mass, you get the oral energy held by that species in the whOle foodchain. So,

Energy = number * mass per unit * energy per unit mass

Do that for Ll if them and you get:

P = 1000
Q = 100
R = 1.8
S = 450 000

In pyramids of energy, the species with most energy is at the base and those with the least are at the top. So, according to this, S should be at the base, followed by P and Q, and R at the top. This is only found in B so that's the answer.

 

[Soldier313]

If it's not too late does anybody understand the relationship between the girth (circumference) of a tree trunk and the cohesion-tension theory? It seems to be a recent favorite amongst the examiners. Thanks

i think the circumference decreases as the cohesion-tension forces decreases

 

[sarahnafea]

it binds to the allosteric site ! the active site is too busy spending quality time with its substrate

aoa

this one too....why wont it alter the active site shape?

View attachment 12860

ric

aoa

this one too....why wont it alter the active site shape?

View attachment 12860

s

 

[sarahnafea]

urgent help for this one pleeeeeeeaaaaaseeeeeView attachment 12861

to say i fully comprehend this question would be an overstatement but what i can tell u is that u pretty much get it by elimination. the other choices sound absurs. antibodies are SPECIFIC to one antigen ! so an antibody complementary to antigen X will never stimulate an immune response to Y. that's pretty much what mr.examiner is trying to say by this seemingly complicated (but really not) question

 

[Soldier313]

to say i fully comprehend this question would be an overstatement but what i can tell u is that u pretty much get it by elimination. the other choices sound absurs. antibodies are SPECIFIC to one antigen ! so an antibody complementary to antigen X will never stimulate an immune response to Y. that's pretty much what mr.examiner is trying to say by this seemingly complicated (but really not) question

yea i guess elimination would be the only way....thanx fr yr help

 

[XPFMember]

aoa

these 2 questions plz...

 

[sarahnafea]

aoa wr wb

need help with this plz

jazakAllah

View attachment 12859

do we need photosynthesis for growth? yes we do because it produces glucose......looking at the other items in the table, is photosynthesis one of other life processes? yup. and finally...what do plants use to respire? oxygen...and what does oxygen do? break down glucose to release CO2...and where does this glucose come from? PHOTOSYNTHESIS! voila

 

[Soldier313]

aoa

these 2 questions plz...
View attachment 12862

part 1
A - thats not true eg look at bacteria 5, week 4 and 5 is same
C - the antibiotic cnt be used for all, look at bacteria 5 again, all the x=zones are greater than 13
D - u cant know this, it may happen in the future
hence by elimination B is the answer

 

[sarahnafea]

for question 40, cell surface area is in the dictionary of the examiner another word for CELL MEMBRANE. cell membrane has hormone receptors. again, another word for cell volume is CYTOPLASM. in the cytoplasm all metabolic reactions take place, for example cellular respiration which produces CO2.

aoa

these 2 questions plz...
View attachment 12862

 

[Nibz]

aoa

these 2 questions plz...
View attachment 12862

Q39. The question clearly states that "Zones of less 13 mm show the presence of resistant bacteria.
1 and 5 have more than 13 mm diameter after 5 weeks. The other 3 have less than that.
So 2, 3 and 4 are the types of bacteria that show resistance.

 

[The King XII]

If it's not too late does anybody understand the relationship between the girth (circumference) of a tree trunk and the cohesion-tension theory? It seems to be a recent favorite amongst the examiners. Thanks

Well think of it like this ehm ehm at night transpiration decrease right so the pressure at the leaf would increase right so what you're doing exactly is that you are reducing the pressure difference, its like a straw right you suck on a straw on top the diameter is reduced you stop sucking or you suck slowly the diameter rarely decreases so back to plants the xylem pressure on top is increased at night due to lack of transpiration, you could say that the pressure on top is canceling pressure at the bottom its like an equlibrium but pressure wise, no pressure diffrence would obviously show no change in the diameter.

 

[Soldier313]

helpppp

 

[Nibz]

helppppView attachment 12875

Pressure potential always has a positive value. So X is for pressure potential.
Solute potential always has a negative value. That's shown by curve Z.
Y is left. That has to be for water potential.

 

[sarahnafea]

Well think of it like this ehm ehm at night transpiration decrease right so the pressure at the leaf would increase right so what you're doing exactly is that you are reducing the pressure difference, its like a straw right you suck on a straw on top the diameter is reduced you stop sucking or you suck slowly the diameter rarely decreases so back to plants the xylem pressure on top is increased at night due to lack of transpiration, you could say that the pressure on top is canceling pressure at the bottom its like an equlibrium but pressure wise, no pressure diffrence would obviously show no change in the diameter.

first of all thanks. second, ur basically saying that if cohesion-tension forces increase as a result of increased transpiration during the day..girth DEcreases>\?

 

[DARK DRAGON]

http://www.xtremepapers.com/papers/CIE/Cambridge International A and AS Level/Biology (9700)/9700_w09_qp_12.pdf
Q19 Plz answer is D

PLZ anyone

 

[XPFMember]

AsSalamoAlaikum Wr Wb!

Is there anyone giving first variant? I mean...tomorrow...if i get doubts, will there be anyone to clear them?