A level Biology: Post your doubts here!

[dornam]

are there any notes for the paper 4 chapters? I haven't found any. Thanks!

 

[Amy Bloom]

Thanks , so part b is fine ? there was air spaces inside the leaf so I didn't know what I'm supposed to do! what lines after the circle? the middle two I thought they were the xylem and phloem

I'll do the diagram and explain everything there.

 

[Amy Bloom]

I did the breaks because there was stomata so I didn't know what to do! It's 2012

It was not my paper. I took part the same year, so i didn't do it.

 

[dornam]

I also have a question regarding respiration and oxygen debt. So when oxygen is not available, the pyruvate obtained from the glycolytic pathway does not enter the link reaction, right? Because of this, it is not combined with coenzyme A to form acetyl coenzyme A therefore the Krebs cycle will not start. So pyruvate will accept hydrogen to convert to lactate by the enzmye lactate dehydrogenase.

Some of this lactate will be oxidised when oxygen is available to CO2 and H2O. How will the rest of it from glycogen? Will it be converted to pyruvate and then to glucose and then to glycogen

 

[Alice123]

what's da function of cytochrome oxidase in oxidative phosphorylation?

 

[Amy Bloom]

what's da function of cytochrome oxidase in oxidative phosphorylation?

It is the last enzyme in the electron transport chain. It receives an electron to form an oxygen molecule which combines with 2 molecules of hydrogen to form water.

 

[aloha]

can anyone help in this...........its frm may june 2009 question number 3!!!!!!!!!!!!!11

 

[Thampi4]

Any notes on biotechnology?

Can someone pls explain batch and continuous culture and y each is used?
Thanks

 

[Amy Bloom]

strangerss
I was trying to upload this since two days and now, finally i could. Well, have a look at my version of the drawing. I did it with pen but you do in pencil for clear photos. You'll see that mine is horizontal, not inclined as in the question paper, sorry for that because i didn't print the paper. Anyways, its the tissues which matter. You'll see also that which "line in the middle" i was talking about last time.
PhyZac Can you please make comments about her drawing please? Maybe another feedback will help her.

 

[Amy Bloom]

can anyone help in this...........its frm may june 2009 question number 3!!!!!!!!!!!!!11

You were told a sample is taken at each hour for 20 hours. It means that, at the end of the 20th hour, you will have 20 samples for each culture system.
Now, you understand that you will have 20 samples for pH 4.0 and 20 samples for pH 5.2.
So, degrees of freedom, v = 20 + 20 - 2 = 38
Hope this helped and good luck

 

[strangerss]

strangerss
I was trying to upload this since two days and now, finally i could. Well, have a look at my version of the drawing. I did it with pen but you do in pencil for clear photos. You'll see that mine is horizontal, not inclined as in the question paper, sorry for that because i didn't print the paper. Anyways, its the tissues which matter. You'll see also that which "line in the middle" i was talking about last time.
PhyZac Can you please make comments about her drawing please? Maybe another feedback will help her.
View attachment 23111

Thank you so much for that , yeah you're version makes much more sense , I didn't know the shape of the tissues should also be drawn the same and apparently I drew the line in the middle wrongly. I think my doubts are clarified , thanks a lot so you're paper was 2012? what did you do regarding the stomata?

 

[Malik777]

Plz Answer & write method :/

 

[Amy Bloom]

Thank you so much for that , yeah you're version makes much more sense , I didn't know the shape of the tissues should also be drawn the same and apparently I drew the line in the middle wrongly. I think my doubts are clarified , thanks a lot so you're paper was 2012? what did you do regarding the stomata?

Welcome dear. Yep the shape of the tissue should be drawn. Well I didn't do that variance paper, sorry.

 

[gary221]

View attachment 23118


Plz Answer & write method :/

B
as it says the divisions on the micrometer are 0.1 mm ie 1*10^(-4) m apart
so 1*10^(-4) m = 40 divisions on the eyepiece graticule
thus, 10*10^(-6) m [the size of the wbc] = x divisions
x = [10*10^(-6) * 40] / [10^(-4)]
x = 4 divisions..
Hope i helped!!

 

[dornam]

Are there some specific diagrams I should know how to draw or in the exam I can have virtually anything?

 

[Thampi4]

Quick question
When answering questions that say with reference to a fig and there is a graph do we always hav to quote values when explaining the trend?

 

[Malik777]

plz answer & explain :/

 

[Malik777]

Quick question
When answering questions that say with reference to a fig and there is a graph do we always hav to quote values when explaining the trend?

yes just once or twice

 

[gary221]

Quick question
When answering questions that say with reference to a fig and there is a graph do we always hav to quote values when explaining the trend?

yes, depending on the marks, u hv to quote 2-3 figs from the graph, n the relationship

 

[Malik777]

yes, depending on the marks, u hv to quote 2-3 figs from the graph, n the relationship

answer mine MCQs :O