AS Biology P1 MCQs Preparation Thread

[Ineedhelp]

* the non competitive inhibtor will bind to the enzyme but not at the active site so this binding will afect the shape of the active site of the enzyme so the substrate cannot fit in the active site of the enzyme any more and as u add more substrate the reaction will not increase so itis non competitive inhbition
* the nitrogen is used to make the bases of the nucleotides such as the adenine and guanine
* for the last point i will see


like it if usefull

With adding more substrate the reaction rate increases in presence of a competitive inhibitor.
however in presence of a non competitive inhibitor does the reaction rate decrease? or remain the same??

 

[Soldier313]

Hi. As for part (A), are you talking about cell cycle ?? If its yes, i guess it happens during interphase. There are G1,S,G2. During S phase, this is where the DNA will replicate. Hope it helps.
For (B,1), the S.A.V ratio refers to the surface area of the alveolus. When there's emphysema, digestive enzyme elastase will be released by the phagocytes. This enzyme will break down the elastin wall of the alveoli, making it less elastic (permanently strecthed). As a result, all the alveoli will enlarge in their shape and thus, reducing the surface area.
(B,2), since S.A.V ratio decreases, this will delay the time for oxgen to diffuses.
For (C), i'm not very sure about this. Is the answer B ? Based on my opinion, peptide bond will form between amino acids (common). Since cystein also contain S, disulphide bridge will form too.

P/S: Plese correct me if I have made any mistakes in the explanations. Thanks

okay thanx for your help
however part A the ms says it occurs during prophase
part C the ms says it is only the peptide bond that will form:S

 

[sahania]

What is the theoretical number of chemically different dipeptides that may be assembled from 12
different types of amino acids?
A 24 B 72 C 144 D 400

How to do it ?????????? help rogue94

Is it B ?

 

[Ineedhelp]

http://www.xtremepapers.com/papers/...and AS Level/Biology (9700)/9700_w08_qp_1.pdf
1,3,4 and 6.
For question 3 why isnt the answer C?
and for question 6 why cant the answer be C? Is it because in glycogen the alpha glucose are linked by 1-4 glycosidic bonds and BRANCH at 1,6. but in the diagram.. they are branching but forming glycosidic bonds :S

Please help ))

 

[sahania]

help needed here !!!!

 

[sophiaaa]

hey.

exam was easy

...what were d questions.had there any repetition????????

 

[Ineedhelp]

Is it B ?

The answer should be C.. 12^2 = 144.
whats the answer?

 

[Soldier313]

hey can someone pleeeaaaseee help me with these:

for the first 2 qns ans is D
for the third screenshot ans is A
please can someone elaborate

 

[sophiaaa]

answer is d.40

The answer should be C.. 12^2 = 144.
whats the answer?

0..how come????

 

[XPFMember]

AsSalamoAlaikum Wr Wb!!!

^ It's B....umm..i dunno i remember solving this question..n i kida learnt the answer

^when amino acids join, it's the peptide bond that is formed. Hence it's D.

^I don't know...is it D?

 

[sahania]

The answer should be C.. 12^2 = 144.
whats the answer?

HuN3yy !! would tell

 

[LimeReem]

Q5 ,20 , 39 , pls explain!
http://www.xtremepapers.com/papers/...nd AS Level/Biology (9700)/9700_w11_qp_12.pdf

 

[XPFMember]

What is the theoretical number of chemically different dipeptides that may be assembled from 12
different types of amino acids?
A 24 B 72 C 144 D 400

How to do it ?????????? help rogue94

I'm pretty sure....it's C

12^2 = 144..

remember it's always x^y
x is the no. of different aminoacids available...and y is the number...which would be in one particular peptide formed...
like here there were 12 different aminoacids formed...x=12
and we had to have 2 of them...so y=2

sahania
sophiaaa

 

[Soldier313]

help needed here !!!!View attachment 12723

for this bit look at this attachment
the part encircled in red measure it, then convert the measurement to micrometers , the answer u get divide it by 2800 (which is the magnification provided)

for example if u measure it and u get say 7 mm that wud be 7000 micrometers divide that by 2800 and you will get 2.5 micrometers, which would be yr answer.......but kindly carry out the measurements yrself as i havent done that

Hope it helps

 

[Ineedhelp]

Dipeptide ; Di means 2. therefore 12^2.

 

[XPFMember]

Q5 ,20 , 39 , pls explain!
http://www.xtremepapers.com/papers/CIE/Cambridge International A and AS Level/Biology (9700)/9700_w11_qp_12.pdf

AsSalamoALaikum Wr Wb!

 

[Soldier313]

Q5 ,20 , 39 , pls explain!
http://www.xtremepapers.com/papers/CIE/Cambridge International A and AS Level/Biology (9700)/9700_w11_qp_12.pdf

for qn 5: u c 40 divisions on the eyepiece graticule equate one division on the stage micrometer
so 40 div = 0.1 mm which is 40 div = 100 micrometers
then u count how many divisions on the eyepiece graticule correspond to the sixe od=f a chloroplast, i got 4 dic=visions
thus u make an eqn: 40 div = 100 micrometers
4 div = ?
cross multiply, u ll gt 10 micrometers, so i guess B is the answer

qn 20 it states the DNA is double stranded hence if they tell u it contains 12 x 10^3 nucleotides , u divide this by 2 to obtain number of nucleotides in 1 strand which will giv u 6 x 10^3 nucleotides, divide this by 3, since 3 nucleotides will form one codon to code for one amino acid, hence u will get 2 x 10^3 as the number of amino acids, therefore i believe C is the answer

qn 39 : net primary productivity = Gross productivity - energy lost in respiration
Gross Productivity = total Light energy - light energy which is reflected
therefore u do: 1000000 - 990000 = 10000 (GP)
10000 - 50000 = 5000
5000/1000000 x 100% = 0.5 %

 

[sahania]

Soldier313

 

[Soldier313]

AsSalamoAlaikum Wr Wb!!!




^ It's B....umm..i dunno i remember solving this question..n i kida learnt the answer



^when amino acids join, it's the peptide bond that is formed. Hence it's D.



^I don't know...is it D?

for part 1 ans is D
part 2 how about the disulfide bridge wont they form bcoz of Sulfur? and H bonds bcoz of the O-H and N-H?
part 3 ans is A

 

[Soldier313]

Soldier313
View attachment 12731View attachment 12732

qn 1 i don't know
qn 2: u measure the small scale bar i got 6 mm = 2nm
then measure membrane i got 22.5 mm , cross multiply u'll get 7.5 nm
7.5 nm = 7.5 x 10^-9 m
hope that helps, the answer is C right?