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A level Biology: Post your doubts here!

mohmed ahmed soliman

mohmed ahmed soliman

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Discuss the effects that variations in carbon dioxide concentration and light intensity have on the rate of photosynthesis. [N’05]

1. carbon dioxide 0.03% ;

2. most likely limits / major limiting / implied low in atmosphere ;

3. increase in carbon dioxide concentration and increase in rate ;

4. during day when light and warm ;

5. ref. to variations in conc. e.g., within canopy / at soil surface ;

6. avp ;

7. light intensity

8. ref. to wavelengths of light ;

9. light saturated below full sun ;

10. idea of limiting and saturation, with other key factor limiting ;

11. light and stomatal aperture ;

12. and temperature of leaf ;

13. day length and season / morning and evening ;

14. high light and damage to pigments ;

15. ref. to light exciting electrons in chlorophyll ;

16. avp ;

help me tow rite anything for this
i cant write anything for MP 4 5 8 9 11 16
i will leave this q blank if it comes in exam
 
P

pundadesh

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Can someone tell me whether we have to know about the various types of transpiration, e.g. stomatal and cutical transpiration
This is because it came out in 9700/21/O/N/12 but I've never come across it in any textbooks
Thanks
 
bubbles1997

bubbles1997

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hello everyone. today is biology 33 practical. I hope someone could post the guess for this. thanks!
 
HumptyR

HumptyR

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slisjunknown said:
View attachment 60616
Can someone help? the answers are the ones underlined in red. I need a explaination
Click to expand...
Q22:
the inhibitor is non-competetive. it binds to the any other point other than the active site of enzyme. the active site of the enzyme attaches with the substrate,then the inhibitor supplied attaches to the enzyme but at any point other than the active site .Hence Both Inhibitor and the Substrate can remain attached to the enzyme at the same time. So as the substrate is already attached there is no change in the shape of the active site . But due to the attachment of the inhibitor,it lowers the rate of forward reaction.
 
qwertypoiu

qwertypoiu

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slisjunknown said:
View attachment 60616
Can someone help? the answers are the ones underlined in red. I need a explaination
Click to expand...
Q3:
The question asks for features that a prokaryote lost to become mitochondria. This means it must be present in prokaryotes but not mitochondria. The only obvious answer is cell wall. We know prokaryotes have cell walls but mitochondria do. Circular chromosomes? Prokaryotes don't have them. Same with endoplasmic reticulum. You can't lose something you never had in the first place. Ribosomes are present in both.
 
slisjunknown

slisjunknown

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HumptyR said:
Q22:
the inhibitor is non-competetive. it binds to the any other point other than the active site of enzyme. the active site of the enzyme attaches with the substrate,then the inhibitor supplied attaches to the enzyme but at any point other than the active site .Hence Both Inhibitor and the Substrate can remain attached to the enzyme at the same time. So as the substrate is already attached there is no change in the shape of the active site . But due to the attachment of the inhibitor,it lowers the rate of forward reaction.
Click to expand...
how can the intial rate reduce? if the active site doesnt change shape the initial activity of the enzyme in this case is not affected
 
A

AnonymousX9

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Guys does anyone have the examiner report for O/N 2015? If yes can please someone send it? I really need it. Thanks.
 
M

My Name

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Syed Umar said:
Thankk youu! Do you have them for Chem and Phy too?
Click to expand...
Welcome.
Here you go:
Chem-https://sharepapers.com/resources/papers/CIE/Cambridge%20A-AS-Level/Chemistry%20(9701)/Winter/
Phys-https://sharepapers.com/resources/papers/CIE/Cambridge%20A-AS-Level/Physics%20(9702)/Winter/
 
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