Edexcel BIOLOGY Doubts!!!!

[shabie]

For CIE A2 (or AS) level students:

I was just going thru the marking schemes of Biology papers and what confuses me is that there are 4 points mentioned for a 2 mark question or sometimes 8 points mentioned for a 4-mark question. Now unlike chemistry or physics, sometimes they don't mention explicitly in their schemes that where all or some are needed so I am just wondering which one is the case? In chemistry and physics, as a general rule, you get one number for one point.

Because 8 points for a 4 point question seem quite a lot to me. They are basically all that you could write in response to that question which is usually not the case as students gets full points for writing different (but correct answers) that may or may not match the scheme.

So would anyone kindly clarify the schemes for biology? For example Question 5(c) for May/June 2010 Paper 42.

[elemis]

Firstly, this is the Edexcel Biology thread. There is another CIE Bio thread for all CIE queries.

Secondly, the markscheme lists several points for that particular question. If you list any THREE of those points you receive all the marks.

That is 1 mark for 1 point. You dont need to list all 4/5 points....

[~ Miss Relina ~]

In june 2004 module 1:
Q 6 (c) answer said post transitional modification what is it exactly ? how it affects the no. of amino acids to be less than the no. of codons ?
Q 6 (d) why in mark scheme the word Two underlined is it a must to be included in my answer if yes then why exactly two 
 plz reply as soon as possible
Thanks in advance             

[~ Miss Relina ~]

In june 2004 module 1:
Q 6 (c) answer said post transitional modification what is it exactly ? how it affects the no. of amino acids to be less than the no. of codons ?
Q 6 (d) why in mark scheme the word Two underlined is it a must to be included in my answer if yes then why exactly two 
 plz reply as soon as possible
Thanks in advance             

plz can any one help withthat

[Amelia]

plz can any one help withthat

Can you post the questions, please? Everyone here doesnt take Edexcel Biology.

Is post translational modification even there in your syllabus?

Anyways, This video might help - http://www.youtube.com/watch?v=OtyhPEyLhvA&feature=related

[~ Miss Relina ~]

Can you post the questions, please? Everyone here doesnt take Edexcel Biology.

Is post translational modification even there in your syllabus?

Anyways, This video might help - http://www.youtube.com/watch?v=OtyhPEyLhvA&feature=related

ok here is the link http://www.xtremepapers.net/Edexcel/Advanced%20Level/Biology/2004%20June/Unit%201%20June%2004.pdf
Thanks for reply

[Amelia]

In june 2004 module 1:
Q 6 (c) answer said post transitional modification what is it exactly ? how it affects the no. of amino acids to be less than the no. of codons ?
Q 6 (d) why in mark scheme the word Two underlined is it a must to be included in my answer if yes then why exactly two 
 plz reply as soon as possible
Thanks in advance             

Posttranslational modification (PTM) is the chemical modification of a protein after its translation. The modification of a newly formed protein; may involve the deletion of amino acids, chemical modification of certain amino acids, or addition of small molecules (eg, phosphate groups or sugars) to certain amino acids.


d -I dont know what 'two' you are talking about but here is the whole answer.
 
http://3.bp.blogspot.com/_KQ8_woKrwiE/SoMNQSl0JhI/AAAAAAAAADE/o0paPK0__YQ/s1600-h/2207.jpg

[~ Miss Relina ~]

Posttranslational modification (PTM) is the chemical modification of a protein after its translation. The modification of a newly formed protein; may involve the deletion of amino acids, chemical modification of certain amino acids, or addition of small molecules (eg, phosphate groups or sugars) to certain amino acids.


d -I dont know what 'two' you are talking about but here is the whole answer.
 
http://3.bp.blogspot.com/_KQ8_woKrwiE/SoMNQSl0JhI/AAAAAAAAADE/o0paPK0__YQ/s1600-h/2207.jpg

Thanks for answering the previous question
here is the mark scheme  Q6(d) answer plz
Thanks in advance Jazak Allah Kairan

[Amelia]

Thanks for answering the previous question
here is the mark scheme  Q6(d) answer plz
Thanks in advance Jazak Allah Kairan

Where's is it, hon?

[~ Miss Relina ~]

Where's is it, hon?

oopps  sorry formy careless
here its my dear 
http://www.xtremepapers.net/Edexcel/Advanced%20Level/Biology/2004%20June/Unit%201%20June%2004%20MS.pdf

[~ Miss Relina ~]

Q 6 (b) in this exam do it tell me http://www.xtremepapers.net/Edexcel/Advanced%20Level/Biology/2005%20June/Unit%201%20June%2005.pdf
 other question in this photo  the darker part the cristea right ?

[Amelia]

oopps  sorry formy careless
here its my dear 
http://www.xtremepapers.net/Edexcel/Advanced%20Level/Biology/2004%20June/Unit%201%20June%2004%20MS.pdf

It's because the first two mRNA codons(a total of 6 bases) enters the ribosomes first. The first codon binds to tRNA molecule having the complementry anticodon & which is carrying the first aminoacid of the polypeptide being synthesised.. The second codon then also attracts a tRNA molecule showing the complementry molecule.

You have to write about atleast two tRNA's to show that you know how the translation takes place. 

[Amelia]

Q 6 (b) in this exam do it tell me http://www.xtremepapers.net/Edexcel/Advanced%20Level/Biology/2005%20June/Unit%201%20June%2005.pdf
 other question in this photo  the darker part the cristea right ?

The infoldings of the mitochondria are the cristae. The 'dark' fluid like material is the matrix.  
----------------------------------------------------
For question 6, I'm not at all sure. But anyways,

Take the two points of coincidents. (Start line of each scale and another point of coindents along the scales.)

Calculate the relationships between them.. On the scale shown there are four divisions on the stage micrometer and 10 divisions on the eyepiece graticule. Thus, 4/10 = 0.4 units. Each unit on the stage micrometer scale is 100 micrometers. Therefore, each division on the graticule scale will be 100 x 0.4 = 40 micrometers. The method is clearly shown here - http://www.xtremepapers.net/CIE/International%20A%20And%20AS%20Level/9700%20-%20Biology/9700_nos_ps_2.pdf

[~ Miss Relina ~]

The infoldings of the mitochondria are the cristae. The 'dark' fluid like material is the matrix.  
----------------------------------------------------
For question 6, I'm not at all sure. But anyways,

Take the two points of coincidents. (Start line of each scale and another point of coindents along the scales.)

Calculate the relationships between them.. On the scale shown there are four divisions on the stage micrometer and 10 divisions on the eyepiece graticule. Thus, 4/10 = 0.4 units. Each unit on the stage micrometer scale is 100 micrometers. Therefore, each division on the graticule scale will be 100 x 0.4 = 40 micrometers. The method is clearly shown here - http://www.xtremepapers.net/CIE/International%20A%20And%20AS%20Level/9700%20-%20Biology/9700_nos_ps_2.pdf

Thanks my dear 

[Amelia]

Thanks my dear 

Anytime