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A level Biology: Post your doubts here!

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Thanks for your solutions regarding my question.

Can anyone make a synthesis of protection of endangered species and rescuing endangered species? The book has lots of info but they are actually only a few ideas...

Does anyone have a definition of biodiversity? I saw the mark schemes and I tried to make one myself:

Biodiversity can be defined as the wide range of habitats, communities including species, the genetic diversity between species and the genetic variation that exists within populations of each species.
 
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What are we supposed to know how to draw in A2?
I don't think we're asked to draw any random cell. But you may be asked to draw the structure of ATP, mitochondria, chloroplasts, plant adaptations (drawing a plant with a thick cuticle, long branching roots, C4 plant structures etc...) and probably human reproductive organs.
 
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No no i meant the question below that,about the eye piece graticule and the stage micrometer?
No no i meant the question below that,about the eye piece graticule and the stage micrometer?
Sorry! I misread your question.
Anyways, the lumen is approximately 8 units wide (from 1.35 - 9.25) on the eyepiece graticule.
8 units on the eyepiece graticule (from 0 - 8) is approximately 9 units on the ruler (from 2.0 - 2.9) (on the second picture)
9 units on the ruler is 0.9 mm (since each division is 0.1 mm, given in the question)
So 8 units on the eyepiece graticule (width of lumen) is 0.9 mm
Hope that makes sense.
 
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how do we perform serial dilution?!?
please someone help me out! i urgently need to know!!
Suppose the volume of the solution you want to serial dilute is 10cm^3 you put it in a small beaker okay and in another beaker you add 9cm^3 of distilled water , then by using s syringe you take 1 cm^3 from the 10cm^3 solution and you add it to the beaker containing the 9cm^3 distilled water , now you have one tenth of the original concentration , like if the original concentration was 5% the new one would be 5/10 = 0.5% , the 0.5% you just made you now use it again , by again putting 9cm^3 of distilled water in another beaker and adding 1cm^3 from the 0.5% concentration to the new beaker this solution would have a concentration of 0.5/10=0.05%.. I hope you got it :)
 
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Sorry! I misread your question.
Anyways, the lumen is approximately 8 units wide (from 1.35 - 9.25) on the eyepiece graticule.
8 units on the eyepiece graticule (from 0 - 8) is approximately 9 units on the ruler (from 2.0 - 2.9) (on the second picture)
9 units on the ruler is 0.9 mm (since each division is 0.1 mm, given in the question)
So 8 units on the eyepiece graticule (width of lumen) is 0.9 mm
Hope that makes sense.

Thank you,Thank you,Thank you,Thank you.
Hope that's enough,cause that's exactly how much im grateful.
 
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Suppose the volume of the solution you want to serial dilute is 10cm^3 you put it in a small beaker okay and in another beaker you add 9cm^3 of distilled water , then by using s syringe you take 1 cm^3 from the 10cm^3 solution and you add it to the beaker containing the 9cm^3 distilled water , now you have one tenth of the original concentration , like if the original concentration was 5% the new one would be 5/10 = 0.5% , the 0.5% you just made you now use it again , by again putting 9cm^3 of distilled water in another beaker and adding 1cm^3 from the 0.5% concentration to the new beaker this solution would have a concentration of 0.5/10=0.05%.. I hope you got it :)

yes i did! thank you sooooo much sis! :D
btw how do you know? do you have any notes, that'd be helpful in some way?
 
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can anyone please explain this one adaption of sorghum in arid conditions? i cant find it in the book :eek: much thxx!!
high silica content / more sclerenchyma / more strengthening tissue - reduces wilting
 
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can anyone please explain this one adaption of sorghum in arid conditions? i cant find it in the book :eek: much thxx!!
high silica content / more sclerenchyma / more strengthening tissue - reduces wilting
1) Thick waxy and waterproof cuticle - reduces water loss and heat absorption (since it reflects off some sunlight)
2) Motor cells which allow it to curl - minimizes water potential gradient --> reduces transpiration rate --> saves water
3) Long branching roots - allow it to absorb as much water as possible in dry conditions
4) Enzymes have a higher optimum temperature - allow it to survive hot conditions
5) It is a C4 plant - minimizes photorespiration
6) Sorghum seeds can enter dormancy when conditions are too arid.
 
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1) Thick waxy and waterproof cuticle - reduces water loss and heat absorption (since it reflects off some sunlight)
2) Motor cells which allow it to curl - minimizes water potential gradient --> reduces transpiration rate --> saves water
3) Long branching roots - allow it to absorb as much water as possible in dry conditions
4) Enzymes have a higher optimum temperature - allow it to survive hot conditions
5) It is a C4 plant - minimizes photorespiration
6) Sorghum seeds can enter dormancy when conditions are too arid.

Are motor cells same as bulliform?

and why do these plants have high silica content?
 
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