A level Biology: Post your doubts here!

[rz123]

a(i) from the curve ( and also the table given below) 96.5%

(ii)fully saturated means 100%, so by unitary method,
%age : vol. of O2
100 : 1.3
96.5 : x
x = (96.5 * 1.3 )/ 100 = 1.25 cm^3

b(i) 24%
(ii) again the method above, vol. of O2= (24 * 1.3)/100 = 0.312 cm^3

it was easy , thanks!

 

[Gémeaux]

really i never checked end of the book (i have a pirated book so can't get it properly from the image at the back)
Thankyou so much it is clear now. the image helped and for the c part i guess its taking place between .48 seconds to .74 s when the ventricles r done with contraction..

np.. only recently i was told that we had the answers too

 

[Gogo]

Hi
How do I differentiate the organnels in a cell???

 

[YoonAda]

Help wanted!!..Do u have notes on biology molecules?

--thanks in advances--^^

 

[larina]

Assalamo Alaikum!

How to find the expected number in a chi-squared test??

ANYONE????

 

[Amy Bloom]

Can somebody recommend me some good books for Biology?

 

[sweetiepie]

For Notes Check here

http://www.xtremepapers.com/community/threads/some-different-notes-website-are-available.10423/

 

[Amy Bloom]

For Notes Check here

http://www.xtremepapers.com/community/threads/some-different-notes-website-are-available.10423/

Humm... I can't access your notes because i have the older version of excel. Could you please save the notes on compatibility mode and post it again. Thank you.

 

[ushaa]

What is the light dependent of photosynthesis ? explain.

 

[tom ed]

does anyone know...how to practice for slides..their labelling...plan diagrams...and stuff....in short any good tips for the plan diagram.....etc.

 

[Amy Bloom]

What is the light dependent of photosynthesis ? explain.

The light dependent stage of photosynthesis, occurs, obviously, when light is present. This stage occurs in the grana of the chloroplasts which contain chlorophyll. The latter contains pigments which allow the passage of light as soon they are absorbed by it. This light energy is converted into chemical energy. Chemical energy is used in making sugar and carbon dioxide.
Hope my answer has been of help to you.

 

[Amy Bloom]

does anyone know...how to practice for slides..their labelling...plan diagrams...and stuff....in short any good tips for the plan diagram.....etc.

You, normally, use the low power objective and draw regions of tissues in the specimen you're provided.

 

[Amy Bloom]

Can somebody recommend me some good books for biology?

 

[Ahmed Ali Akbar]

help me out in mcq 24 of oct nov 05..P1.

 

[asexamskillme111]

help me out in mcq 24 of oct nov 05..P1.

The nitrogenous base uracil replaces thyamine in RNA, right? So when uracil is 25, thyamine will be 0. Now we know that option C is thyamine. In DNA, thyamine bonds with adenine. So the percentages of thyamine present has to be very close to adenine. The closest numbers are in B. So the answer is B.

 

[Amy Bloom]

The nitrogenous base uracil replaces thyamine in RNA, right? So when uracil is 25, thyamine will be 0. Now we know that option C is thyamine. In DNA, thyamine bonds with adenine. So the percentages of thyamine present has to be very close to adenine. The closest numbers are in B. So the answer is B.

How did you know that when uracil is 25, thymine would be 0? What is the relationship?

 

[larina]

Noone told me how to find the expected number in a chi-squared test...
there's a question in october/november 2011 paper 53, Q2 b) ii.

 

[hassam]

Noone told me how to find the expected number in a chi-squared test...
there's a question in october/november 2011 paper 53, Q2 b) ii.

example.....u performed a cross and ratio of one trait to other is 3:1......so if total number is 100 then expected number wud be 75 for one trait and 25 for the other one....its just based on the percentage obtained after doing a genetic cross

 

[Paradoxical]

How did you know that when uracil is 25, thymine would be 0? What is the relationship?

In RNA, there is no thymine. It's replaced by uracil. So if uracil is present, thymine can't be.

 

[omg]

can any1 giv a note on Q.1o (b) nov 2011!
"describe how u would separate choloplast pigments using chromatography" ?
please!