A level Biology: Post your doubts here!

[osama ahmed ibrahim]

what does it mean no iolating mechanism operating

 

[funky brat]

what does it mean no iolating mechanism operating
View attachment 60339

It means that the species that are going to interbreed there is no isolating mechanism between them. For example they are not geographicallly or reproductively isolated from each other. Only species that acre capable of breeding are made to interbreed artificially.

 

[osama ahmed ibrahim]

describe role of gibberelin in stem elongation
27 AVP ; e.g. ref. to different forms of gibberellins / there is interaction between / gibberellin
and other plant growth regulators
i didnt understand this MS point

 

[osama ahmed ibrahim]

It means that the species that are going to interbreed there is no isolating mechanism between them. For example they are not geographicallly or reproductively isolated from each other. Only species that acre capable of breeding are made to interbreed artificially.

interbreed
with reference to an animal) breed or cause to breed with another of a different race or species.
"wolves and dogs can interbreed"
does interbreed happen with different species

 

[funky brat]

interbreed
with reference to an animal) breed or cause to breed with another of a different race or species.
"wolves and dogs can interbreed"
does interbreed happen with different species

Yes different but closely related species.

 

[slisjunknown]

Are channel proteins required for Substrate level Phosphorylation? Is ATPase a channel protein?

 

[osama ahmed ibrahim]

genetic screening and dna sequencing is on syllabus?

 

[My Name]

genetic screening and dna sequencing is on syllabus?

Yes

 

[osama ahmed ibrahim]

Yes

no notes for them in book
do u have notes

 

[osama ahmed ibrahim]

Coelacanth haemoglobin has a very high affinity for oxygen, suggesting that coelacanths,
which have been captured at depths of between 200 m and 400 m, live in water that has
a low concentration of oxygen.
Explain how an environmental factor, such as the low concentration of oxygen in deep
water, can act:
as a stabilising force in natural selection
ref. mutation ; ?? what should i write for this

(ii) as an evolutionary force in natural selection.

1. ref. change in oxygen concentration ;
2. (low) oxygen concentration acts as selective agent ;
3. some individuals (in population) are better adapted ;
4. these are more likely to survive ; ora
5. directional selection ;
6. sketch graph ;
7. populations develop in different concentrations of oxygen ;
8. disruptive selection ;
9. sketch graph ;
help me to write answer for this
MP 1 is not clear and 7

 

[My Name]

no notes for them in book
do u have notes

Genetic screening page 467

 

[osama ahmed ibrahim]

Suggest how the stocks of Atlantic cod may be increased.
stop / reduce, fishing ; A correct ref. to quotas / moratorium
2. ref. to size of nets ;
3. ref. to methods of fishing ;
4. control pollution ;
5. education ;
6. captive breeding and release / restocking from fish farms ;
7. ref. to marine reserves ;

MP2 AND 3 IS NOT CLEAR

 

[funky brat]

Suggest how the stocks of Atlantic cod may be increased.
stop / reduce, fishing ; A correct ref. to quotas / moratorium
2. ref. to size of nets ;
3. ref. to methods of fishing ;
4. control pollution ;
5. education ;
6. captive breeding and release / restocking from fish farms ;
7. ref. to marine reserves ;

MP2 AND 3 IS NOT CLEAR

2- nets with small holes prohibited because catches smaller fish which are economically insignificant. Also when small fish are not allowed to grow the stocks wipe out with the passage of time.
3- Any fishing method which is not conducive to the growth of fish is discouraged. The example of this could be the same thing as in point 2.

 

[funky brat]

Coelacanth haemoglobin has a very high affinity for oxygen, suggesting that coelacanths,
which have been captured at depths of between 200 m and 400 m, live in water that has
a low concentration of oxygen.
Explain how an environmental factor, such as the low concentration of oxygen in deep
water, can act:
as a stabilising force in natural selection
ref. mutation ; ?? what should i write for this

(ii) as an evolutionary force in natural selection.

1. ref. change in oxygen concentration ;
2. (low) oxygen concentration acts as selective agent ;
3. some individuals (in population) are better adapted ;
4. these are more likely to survive ; ora
5. directional selection ;
6. sketch graph ;
7. populations develop in different concentrations of oxygen ;
8. disruptive selection ;
9. sketch graph ;
help me to write answer for this
MP 1 is not clear and 7

point 1 is just the stimulus that triggers the selections.
point 7 links the development of the fishes in areas with different oxygen conc to the evolution. For example the fishes that grow in low oxygen conc may evolve to have lungs that are larger in size ( contain more alveoli) Couldn't think of a better example sorry.

 

[osama ahmed ibrahim]

The optimum pH for the activity of rubisco is pH8.
Explain why the illumination of chloroplasts leads to optimum pH conditions for rubisco.
excited electrons leave, chlorophyll a / photosystem ;
2 pass along ETC ;
3 protons present from photolysis ;
4 protons (pumped) into intermembrane space ;
5 rubisco is in stroma ;
6 idea that protons leaving stroma raises pH ;

 

[osama ahmed ibrahim]

help i didnt understand

 

[kareem22010]

can anybody please help and tell me if i am checking the markscheme the right way or not?:



My answer:B cells are responsible for production of insulin.if they are destroyed, no insulin will be secreted .this will lead to diabetes as lack of insulin results in no stimulation at all for liver cells to uptake glucose and decrease it's concentration in the blood and store it as glycogen.this leaves glucose concentration to rise above normal level in blood and negative feedback or homestoasis is not possible.

how many points will my answer earn?

any help is very appreciated.

 

[kareem22010]

di

The optimum pH for the activity of rubisco is pH8.
Explain why the illumination of chloroplasts leads to optimum pH conditions for rubisco.
excited electrons leave, chlorophyll a / photosystem ;
2 pass along ETC ;
3 protons present from photolysis ;
4 protons (pumped) into intermembrane space ;
5 rubisco is in stroma ;
6 idea that protons leaving stroma raises pH ;

did you find this question in CIE past papers or OCR?

 

[osama ahmed ibrahim]

di

did you find this question in CIE past papers or OCR?

cie 9700 paper 4

 

[kareem22010]

cie 9700 paper 4

And where did you find this question?
(if you found it in a past paper, in which year did you find it?)