A level Biology: Post your doubts here!

[roxylara]

1.Here you just need to match the codons in fig6.1 with the aminoacids in the table6.1
as GUG is valine, CAC is histidine, CUG is leucine ......
the sequence will be: val-his-leu-pro-glu-glu-lys-ser-ala
2.The viral particle i think it should be one of the two with the dark areas in the middle
(Make sure to convert the length to nm)
For the actual size= size of the virus/Magnification

Ah I just realised everything was in the question-silly me. Thankyou

 

[thats_me]

Ah I just realised everything was in the question-silly me. Thankyou

Yeah no problem

 

[Snowysangel]

Okay so:

Hello ! Can someone please explain the following:
Q 2 , Q11 ,Q27 , Q30
http://papers.xtremepapers.com/CIE/Cambridge International A and AS Level/Biology (9700)/9700_w11_qp_13.pdf

A is number if nutrients
B is intensity of light
C is no of producers
D is no of primary consumers

 

[Wolfgangs]

How to solve Q23 in this paper?

http://papers.xtremepapers.com/CIE/...nd AS Level/Biology (9700)/9700_s13_qp_13.pdf

 

[Gehad Mohamed]

Q2:- number of primary consumers will be more in summer as the number of producers will be more... in the graph we have B n D that shows almost the same curve... but as no. of primary consumers r always less than no. of producers so the ans is D

Q11:- The walls of alveoli n capillaries r moist in order to prevent friction n bursting of the walls...it has nthng with gaseous exchnge n the ans is C

Q27:- for repairing a complete tissue is to be repaired not a single cell..

Q30:- As frm DNA, RNA is formed n then protein is formed then the ans is amylase... (all enzymes r globular protein in nature)

Thanks sooooooo much

 

[Gehad Mohamed]

Okay so:

A is number if nutrients
B is intensity of light
C is no of producers
D is no of primary consumers

Thanks alot

 

[ZaqZainab]

How to solve Q23 in this paper?

http://papers.xtremepapers.com/CIE/Cambridge International A and AS Level/Biology (9700)/9700_s13_qp_13.pdf

there are 2 anit codones not necessary both are used
they have mentioned he sequence glycine – arginine – lysine – serine
for glycine if we take CCA the basses on the DNA will be CCT and if we take CCU then again the basses on the DNA will be CCT the only answer which has CCT as the first one in the sequence is B

 

[kitkat <3 :P]

http://papers.xtremepapers.com/CIE/...and AS Level/Biology (9700)/9700_s09_qp_2.pdf
Q4 and 5 please

 

[ZaqZainab]

http://papers.xtremepapers.com/CIE/Cambridge International A and AS Level/Biology (9700)/9700_s09_qp_2.pdf
Q4 and 5 please

can you specify which part?

 

[kitkat <3 :P]

The whole question please

 

[Snowysangel]

http://papers.xtremepapers.com/CIE/Cambridge International A and AS Level/Biology (9700)/9700_s09_qp_2.pdf
Q4 and 5 please

In q4)
Process A is transcription, molecule B is the tRNA, structure C is the ribosome(because that's where the polypeptide chain is being assembled) and sequence D is the anticodon.

Similarities:
Both have amino acids as their mononers
Both have a total of 4 polypeptide chains

Difference:
All 4 polypeptide chains are identical in catalase

It has 4 active sites

Differepearanve of substrate: iodine test
Appearance if product: Benedict's reagent

 

[kitkat <3 :P]

In q4)
Process A is transcription, molecule B is the tRNA, structure C is the ribosome(because that's where the polypeptide chain is being assembled) and sequence D is the anticodon.

Similarities:
Both have amino acids as their mononers
Both have a total of 4 polypeptide chains

Difference:
All 4 polypeptide chains are identical in catalase

It has 4 active sites

Differepearanve of substrate: iodine test
Appearance if product: Benedict's reagent

Thanks alot

 

[ZaqZainab]

http://papers.xtremepapers.com/CIE/Cambridge International A and AS Level/Biology (9700)/9700_s09_qp_2.pdf
Q4 and 5 please

The whole question please

Sure
Q4
(a) i) A as you can see the mRNA is being made and mRNA is made by transcription
B this is tRNA
C ribosome
D anticodone "on a tRNA"
(ii) You need to know about the structure of Haemoglobin for this
Similarities
they both have 4 subunits
and the haem group
Difference
The 4 subuntis in heamoglobin are actually 2 alpha and 2 beta but here all of them are same
(iii) as you can see from the Fig 4 heam groups to each sub units cause they have 4 active sites
(iv) disappearance of substrate do a starch test(iodine)
appearance of product maltose test (Benedict) maltose is a reducing sugar
Q5
(a) Q-Xylem
R- outside the leaf
Water moves from a Higher concentration to lower concentration
Via SYMPLAST which is the through cytoplasm connected by PLASMODESMATA.
Via APOPLAST which is through cell walls
It reached spongy mesophyl cells
from there evaporation of water takes place from there cell wall to the air spaces
as there is lower water potential at R water diffuses from the airspaces to R
through stomata :3
(b) Xylem has no cytoplasm
so the water flow is uninterrupted and will be faster
Xylem has linin made cell walls
so it can sand the pressure and give support to the plant
Xylem has wide lumen without any end walls
so large volume of water can be transported at a time

 

[kitkat <3 :P]

Sure
Q4
(a) i) A as you can see the mRNA is being made and mRNA is made by transcription
B this is tRNA
C ribosome
D anticodone "on a tRNA"
(ii) You need to know about the structure of Haemoglobin for this
Similarities
they both have 4 subunits
and the haem group
Difference
The 4 subuntis in heamoglobin are actually 2 alpha and 2 beta but here all of them are same
(iii) as you can see from the Fig 4 heam groups to each sub units cause they have 4 active sites
(iv) disappearance of substrate do a starch test(iodine)
appearance of product maltose test (Benedict) maltose is a reducing sugar
Q5
(a) Q-Xylem
R- outside the leaf
Water moves from a Higher concentration to lower concentration
Via SYMPLAST which is the through cytoplasm connected by PLASMODESMATA.
Via APOPLAST which is through cell walls
It reached spongy mesophyl cells
from there evaporation of water takes place from there cell wall to the air spaces
as there is lower water potential at R water diffuses from the airspaces to R
through stomata :3
(b) Xylem has no cytoplasm
so the water flow is uninterrupted and will be faster
Xylem has linin made cell walls
so it can sand the pressure and give support to the plant
Xylem has wide lumen without any end walls
so large volume of water can be transported at a time

Thanks alot zainab

 

[mr dam bhai]

Thanks alot zainab

can any one help me with Q3 b june 2012 paper 21 biology

 

[princeali97]

can any one help me with Q3 b june 2012 paper 21 biology

Yeah i'll try.As u can see the %saturation of haemoglobin molecule is less for each partial pressure of oxygen(for sickle cell anaemia) it is clear that the haemoglobin molecule can release its oxygen more readily hence it compensates the lack of normal RBCs in blood.I hope u understood.

 

[Shada Mohammed]

Q2:- number of primary consumers will be more in summer as the number of producers will be more... in the graph we have B n D that shows almost the same curve... but as no. of primary consumers r always less than no. of producers so the ans is D

Q11:- The walls of alveoli n capillaries r moist in order to prevent friction n bursting of the walls...it has nthng with gaseous exchnge n the ans is C

Q27:- for repairing a complete tissue is to be repaired not a single cell..

Q30:- As frm DNA, RNA is formed n then protein is formed then the ans is amylase... (all enzymes r globular protein in nature)

Can you please explain question 7 in the same exam

 

[kitkat <3 :P]

Someone help me with the dissociation curve n bohr effect I dont underdtand it

 

[mehria]

Can you please explain question 7 in the same exam

first we have to find the value for the smallest division in eyepiece graticule...
for that :_ 0.1/40= 2.5 x 10^-3 mm
cnge mm into micrometer by multiplying 1000 with ur value
(2.5 x 10^-3) x 1000 = 2.5 micrometer <------- ths is the value for the smallest division in eyepiece graticule

frm the second diagram choose any nucleus , measure its diameter
in the diagram one of the nuclues' diameter is 10
so:- 10 x 2.5 = 25 micrometer

 

[Mohammed salik]

first we have to find the value for the smallest division in eyepiece graticule...
for that :_ 0.1/40= 2.5 x 10^-3 mm
cnge mm into micrometer by multiplying 1000 with ur value
(2.5 x 10^-3) x 1000 = 2.5 micrometer <------- ths is the value for the smallest division in eyepiece graticule

frm the second diagram choose any chloroplast , measure its diameter
in the diagram one of the chloroplast's diameter is 3
so:- 3 x 2.5 = 7.5 micrometer
it is closer to 8 then our ans will b B

No I think Ans would Be 25 micro meter( C!!)
It says Nucleus not Cholroplast u misread it Againnnnnnnnnnnnnnnnn!!