IGCSE/GCSE/O & A Level/IB/University Student Forum

Qualification => Subject Doubts => GCE AS & A2 Level => Sciences => Topic started by: thecandydoll on May 14, 2010, 01:59:16 am

Title: biology P2 doubt
Post by: thecandydoll on May 14, 2010, 01:59:16 am

What are the structural features of both xylem and phloem that enable it to perform its functions!

Title: Re: biology P2 doubt
Post by: dinar on May 14, 2010, 05:13:24 am

If I am not mistaken, xylem has pits along it. Pits allow water to diffuse out of the xylem and go to the neighbouring cells. Xylem also has lignified walls which prevent water lost. Phloem has sieve plates which support the phloem.

How many marks does the question require?  :)

Title: Re: biology P2 doubt
Post by: DucatiM on May 14, 2010, 08:25:53 am

for the xylem thing... the end walls of the dead cells have been broken down thus providing a long uninterrupted pathway for the movement of large volumes of water. Also, it is thin allowing water to be capillarized

for the phloem, It forms plasmodesma with the companion cell which allows it to be provided with enzymes, energy and cytoplasm to carry out its function. It has no lignified cell walls which prevents it from dying out