# alevel biology

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Thread starter 1 month ago
#1
Plants need water to survive.
(a) Water enters plants through the roots. Most roots are covered in root hairs.
The number of root hairs per mm2 of root surface is described as the density of root hairs.
The density of root hairs can vary between and within species.
A scientist examined a plant root. The plant root had a diameter of 2mm. In 1mm of root
length the scientist counted 440 root hairs.
Calculate the density of root hairs on the root the scientist examined.
Use the formula: Surface area of cylinder = 2πr(r + l)
Give your answer to 2 significant figures.
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1 month ago
#2
(Original post by ×ish×212)
Plants need water to survive.
(a) Water enters plants through the roots. Most roots are covered in root hairs.
The number of root hairs per mm2 of root surface is described as the density of root hairs.
The density of root hairs can vary between and within species.
A scientist examined a plant root. The plant root had a diameter of 2mm. In 1mm of root
length the scientist counted 440 root hairs.
Calculate the density of root hairs on the root the scientist examined.
Use the formula: Surface area of cylinder = 2πr(r + l)
Give your answer to 2 significant figures.
I'd love to help but just want to say that wen it was my mocks they didn't put it in cause even the teachers were a bit lost
me and my friends thought you do
2xpix1(1+1) and do you times by 440
but not too sure sorry just wait for someone else to clarify
Last edited by R_A_A; 1 month ago
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1 month ago
#3
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1 month ago
#4
(Original post by acestar123)
can I just plz ask why do you divide- is it to find one hair--but I thought you times as it's asking for density of root hairSSS?
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