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A level Biology: Post your doubts here!

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dornam

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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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Irfan1995

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narutogirl said:
What are we supposed to know how to draw in A2?
Click to expand...
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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Irfan1995

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Noor Ahmad said:
No no i meant the question below that,about the eye piece graticule and the stage micrometer?
Click to expand...
Noor Ahmad said:
No no i meant the question below that,about the eye piece graticule and the stage micrometer?
Click to expand...
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.
 
S

strangerss

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Notorious Angel said:
how do we perform serial dilution?!?​
please someone help me out! i urgently need to know!!​
Click to expand...
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 :)
 
Noor Ahmad

Noor Ahmad

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Irfan1995 said:
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.
Click to expand...

Thank you,Thank you,Thank you,Thank you.
Hope that's enough,cause that's exactly how much im grateful.
 
Notorious Angel

Notorious Angel

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strangerss said:
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 :)
Click to expand...

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?
 
externityxzx

externityxzx

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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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Irfan1995

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externityxzx said:
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
Click to expand...
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.
 
Noor Ahmad

Noor Ahmad

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Irfan1995 said:
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.
Click to expand...

Are motor cells same as bulliform?

and why do these plants have high silica content?
 
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