Gas Exchange in Plants

SBI 3U

Plants need Oxygen too.

• Plants obtain the gases they need through their leaves.

• They require oxygen for respiration and carbon dioxide for photosynthesis.

http://www.chemsoc.org/networks/LearnNet/cfb/images/12A.jpg

The gases diffuse into the intercellular spaces of the leaf through pores, which are normally on the underside of the leaf – stomata. From these spaces they will diffuse into the cells that require them.

The Epidermis of a leaf.

http://virtual.yosemite.cc.ca.us/randerson/Lynn's%20Bioslides/27.jpg

Stomatal opening and closing depends on changes in the turgor of the guard cells. When water flows into the guard cells by osmosis, their turgor increases and they expand. If the guard cells loose water the opposite happens and the pore closes.

http://biology.unlv.edu/Schulte/Anatomy/Leaves/PopulusStomata.jpg

http://www.plantsci.cam.ac.uk/Webb/images/stomata.jpg

http://bio1151.nicerweb.com/Locked/media/ch36/36_15GuardCellFunction.jpg

http://www.progressivegardens.com/knowledge_tree/stomata.jpg

Lenticels – pores in the bark of stems

http://sciencecity.oupchina.com.hk/biology/student/glossary/img/lenticels.jpg

http://www.treedictionary.com/DICT2003/IMAGES/LENTICELS%20BIRCH.jpg

http://www.digitalfrog.com/resources/archives/leaf.jpg

http://www.biotopics.co.uk/plants/leafst.html

http://home.comcast.net/~john.kimball1/BiologyPages/S/stoma.gif

http://www.northern.edu/ramsayj/etechWeb/images/leaves/leaf%20example1%20copy.JPG

Transport in plants

SBI 3U

http://www.bbc.co.uk/schools/gcsebitesize/img/bixylemphloem.gif