Xylem and Phloem - AS Biology Revision - OCR (Unit 1.2.3)

[Kanabaro]

distributed*

[LynchMuK]

Lignin is also for waterproofing

[debby101]

What is this song called?

[anon3339]

@debby101 Florence and the machine- dog days are over

[debby101]

@anon3339 Thank you. This video really helped aswell..please do some more

[coolkat787]

Thanks, that was very useful,!

[tbcw1000]

thank you very much that was very useful! :)

[nirvanafreak5364]

its good except it goes to fast..

[safaanej]

thank you so much :)

[2pakaveli]

Will you sit my exam tomorrow?

Thank you kind sir x

[Biologybytes]

For great biology videos

[jalalpurjattan]

0:40

Dont you mean plants have a large sa : vol ratio instead of small?????

[OCRBiologyAS]

@jalalpurjattan nope, plants have a small surface area to volume ratio! 

[jalalpurjattan]

@jalalpurjattan Plants dont need a transport system for oxygen and co2 because their matabolism is lower, sa to vol ratio is large and diffusion thorugh air spaces and cells suffice!!

[OCRBiologyAS]

@jalalpurjattan From the OCR textbook: "there are many cells inside the plant that are not near the surface of the plant which need a transport system to provide it with water and nutrients to survive".

Also, "Once a multicellular organisms becomes larger, its surface-area-to-volume ratio becomes smaller and its cells needs more supplies".