AS Biology P1 MCQs Preparation Thread

[fizzah96]

hey...i have a question.
A tree carries out photosynthesis and provides organic compounds for other organisms in a
forest. It takes carbon dioxide from and returns oxygen to the atmosphere. It takes water from the
soil into its roots and its leaves lose water to the atmosphere. Many other organisms live in the
tree.

Which term applies to the description of the tree?
A
ecosystem
B
habitat
C
niche
D
trophic level
this question came twice in the exam in oct nov 2009 and oct nov 2012 but in both cases answer was different.can anyone explain this to me?​

 

[Aries_95]

hey...i have a question.​

A tree carries out photosynthesis and provides organic compounds for other organisms in a​

forest. It takes carbon dioxide from and returns oxygen to the atmosphere. It takes water from the​

soil into its roots and its leaves lose water to the atmosphere. Many other organisms live in the​

tree.​

​

Which term applies to the description of the tree?​

A​

ecosystem​

B​

habitat​

C​

niche​

D​

trophic level​

this question came twice in the exam in oct nov 2009 and oct nov 2012 but in both cases answer was different.can anyone explain this to me?​

Its Niche(C) because the description above refers to the role played by the tree.

 

[Aries_95]

What could be produced in a terminating step during the bromination of propane (Attached)

This a thread for Biology MCQ's brother!

 

[ahmed abdulla]

This a thread for Biology MCQ's brother!

OMG ... by mistake
if u can help that will be good

 

[fishcook]

Q7 Turgid plant tissue is placed in a solution which has the same solute potential as the contents of
the cells. The diagram shows a cell after one hour.
Which equation describes the value of the pressure potential for this cell?
A pressure potential = solute potential of the cell
B pressure potential = solute potential of the external solution
C pressure potential = water potential of the cell
D pressure potential = zero

why is the answer D? its from winter 03​

Q13 How does increasing substrate concentration affect the rate of an enzyme-catalysed reaction in
the presence of a competitive inhibitor?
A) The rate of the reaction decreases.
B) The rate of the reaction decreases initially and then recovers.
C) The rate of the reaction increases.
D) The rate of the reaction is not affected.

why is the answer C? please help​

 

[fishcook]

http://papers.xtremepapers.com/CIE/...nd AS Level/Biology (9700)/9700_w10_qp_12.pdf
Q8. the answer is C but why is the 4th statement correct

 

[Gimmick]

AND...if they are asking whether the disease can pass through breastfeeding, what about TB and cholera? I mean bacteria cannot pass through breast feeding!!!

But viruses can...

 

[Aries_95]

But viruses can...

and you mean that viruses cause Cholera and TB?????? Are you serious???

 

[Gimmick]

http://papers.xtremepapers.com/CIE/Cambridge International A and AS Level/Biology (9700)/9700_w10_qp_12.pdf
Q8. the answer is C but why is the 4th statement correct

Because it'd be weaker if there were no covalent bonds
It's asking for things affecting the tensile strength of collagen - collagen is strong because of its helical structure (more hydrogen bonds), and the small R group means that when individual strands of collagen are placed parallel to each other, the hydrogen bonds would be stronger than if the R group was large (the ratio of hydrogen bonds to individual atoms would be larger if the R group was smaller); the covalent bonds affect the tensile strength because they prevent the strand from breaking when a force is exerted on them. If there were no covalent bonds, it'd be much, much weaker because when there's a bunch of strands and hundreds of covalent bonds to make a single, say, hair, it'd be very easy to tear -- those bonds add up, and so the more bonds there are between molecules, the stronger things get.

At least, that's what I think.

Q7 Turgid plant tissue is placed in a solution which has the same solute potential as the contents of​

the cells. The diagram shows a cell after one hour.​

Which equation describes the value of the pressure potential for this cell?​

A pressure potential = solute potential of the cell​

B pressure potential = solute potential of the external solution​

C pressure potential = water potential of the cell​

D pressure potential = zero​

​

why is the answer D? its from winter 03​

Q13 How does increasing substrate concentration affect the rate of an enzyme-catalysed reaction in ​

the presence of a competitive inhibitor? ​

A) The rate of the reaction decreases. ​

B) The rate of the reaction decreases initially and then recovers. ​

C) The rate of the reaction increases. ​

D) The rate of the reaction is not affected. ​

​

why is the answer C? please help​

Q7 - The pressure potential is basically the pressure exerted by the water on the cell wall, and as more water enters the cell, the pressure potential increases. By default, the pressure potential is 0 (cell contents); if excess water entered the cell, the cell would be turgid, and so the pressure potential would be greater than 0. If water left the cell, it would be plasmolysed, and so the pressure potential would be less than 0. But since the solute potential of the surroundings of the cell is the same as the solute potential of the inside of the cell, it should generally follow that the water potential is also the same. Since the water potential is the same, it is an isotonic solution - no water leaves or enters the cell, in net. As a result, the pressure potential is 0.

Q13 - For this, try to look at what would happen when there is no competition from an inhibitor, aka a normal enzyme-catalysed reaction. Increasing the substrate concentration would increase the rate of the reaction, naturally, because there are more molecules (a la the kinetic model). Now, if you add a competitive inhibitor, with a normal amount of substrate, the rate would decrease. However, increasing the substrate concentration would result in the rate of reaction increasing, because even though there is a competitive inhibitor, there is a higher number of substrate and so it would increase. I think.
However, if it were a non competitive inhibitor, it would not affect the rate, because the active site would be distorted.

 

[fizzah96]

can anyone explain question 12? what are hydrostatic bonds?

 

[fishcook]

Because it'd be weaker if there were no covalent bonds
It's asking for things affecting the tensile strength of collagen - collagen is strong because of its helical structure (more hydrogen bonds), and the small R group means that when individual strands of collagen are placed parallel to each other, the hydrogen bonds would be stronger than if the R group was large (the ratio of hydrogen bonds to individual atoms would be larger if the R group was smaller); the covalent bonds affect the tensile strength because they prevent the strand from breaking when a force is exerted on them. If there were no covalent bonds, it'd be much, much weaker because when there's a bunch of strands and hundreds of covalent bonds to make a single, say, hair, it'd be very easy to tear -- those bonds add up, and so the more bonds there are between molecules, the stronger things get.

At least, that's what I think.



Q7 - The pressure potential is basically the pressure exerted by the water on the cell wall, and as more water enters the cell, the pressure potential increases. By default, the pressure potential is 0 (cell contents); if excess water entered the cell, the cell would be turgid, and so the pressure potential would be greater than 0. If water left the cell, it would be plasmolysed, and so the pressure potential would be less than 0. But since the solute potential of the surroundings of the cell is the same as the solute potential of the inside of the cell, it should generally follow that the water potential is also the same. Since the water potential is the same, it is an isotonic solution - no water leaves or enters the cell, in net. As a result, the pressure potential is 0.

Q13 - For this, try to look at what would happen when there is no competition from an inhibitor, aka a normal enzyme-catalysed reaction. Increasing the substrate concentration would increase the rate of the reaction, naturally, because there are more molecules (a la the kinetic model). Now, if you add a competitive inhibitor, with a normal amount of substrate, the rate would decrease. However, increasing the substrate concentration would result in the rate of reaction increasing, because even though there is a competitive inhibitor, there is a higher number of substrate and so it would increase. I think.
However, if it were a non competitive inhibitor, it would not affect the rate, because the active site would be distorted.

Thank you
really appreciate it

one more question: Q26 from http://papers.xtremepapers.com/CIE/...nd AS Level/Biology (9700)/9700_s10_qp_11.pdf
what does the question ask? like water potential before or after translations has occurred?

 

[fishcook]

http://papers.xtremepapers.com/CIE/...nd AS Level/Biology (9700)/9700_w11_qp_11.pdf
Q40

 

[Sakib]

w 11/paper 11/ Q-6,14,30, 34,40. Somebody help me!

 

[Sughontha]

im confused about the protein structures needed to maintain shape of active site? is it only 3° or primary also important?because of the amino acids?

 

[Sughontha]

Its Niche(C) because the description above refers to the role played by the tree.

but the answer in tye w12 paper is ecosystem!

 

[Aries_95]

im confused about the protein structures needed to maintain shape of active site? is it only 3° or primary also important?because of the amino acids?

Primary, secondary and tertiary all are important to maintain shape of active site.

 

[Sughontha]

ote="Aries_95, post: 603724, member: 73536"]Primary, secondary and tertiary all are important to maintain shape of active site.[/quote]

Primary, secondary and tertiary all are important to maintain shape of active site.

w02 question 12 then??

 

[Aries_95]

ote="Aries_95, post: 603724, member: 73536"]Primary, secondary and tertiary all are important to maintain shape of active site.

w02 question 12 then??[/quote]

The questions asks for the globular shape of the enzyme. since globular shape is formed due to interactions between the R groups of the side chain giving rise to a ball shaped molecule, the globular shape is maintained by the tertiary structure (Tertiary structure involves interactions between the R-groups).

 

[Sughontha]

so,the general shape of the active site is also dependant on 3° only but the enzyme specificity is dependent on all 1,2,3,4°?

 

[ahmed abdulla]

18 Which statement describes a cell that is capable of reproduction and belonging to a haploid
organism?
A It has chromosomes that contain one polynucleotide chain.
B It is capable of carrying out a reduction division to form gametes.
C It possesses two copies of each gene as a result of fertilisation.
D It will undergo cell division by mitosis during asexual reproduction.

ans is D .. but i am pretty sure its B ... from o/n 2009 va'11