Water Transport through a plant

By: Aisha Al Misnad & Luma Mansi

• Once inside the root hair, the water needs to be transferred to the xylem, the vascular tissue involved in water transport through the plant. In roots, the vascular tissue is found in a central column, separated from the cortex parenchyma cells by a single layer of cells called the endodermis.

How the Water Transports

• There is a water concentration gradient across the root which means that water which has entered the root hair cell continues to move across the cortex to the endodermis by osmosis. The route taken by much of the water is through the cellulose cell walls, the rest of the water either passes through the cytoplasm of the cells or through the cell vacuoles.

• Once it reaches the endoderm cells, the water is forced to move through the cytoplasm. This is because the radial and transverse cell walls of the young endodermis are impregnated with an impervious material. The gradient of water concentration that exists across the cortex creates a pushing force called "root pressure” that pushes the water across. Root pressure can happen by cutting a stem at soil level, after a time, droplets of water can be seen exuding from the cut surface.

• In some plants the process occurs naturally when droplets of water are forced through special pores on the leaf edges.

More information

• Vascular tissue, also known as xylem, transports water throughout the plant. Due to the transpiration pull, a continuous stream or column is formed throughout the plant and this movement continuously supplies water.

Photosynthesis

• Green plants are called producers because they make their own food by photosynthesis. Most photosynthesis takes place in the leaves of the plant. Chlorophyll in the leaves traps light energy from the sun. The energy is used to change water and carbon dioxide into sugar and oxygen.

Bibliography

• http://users.rcn.com/jkimball.ma.ultranet/BiologyPages/X/Xylem.htm

• http://wiki.answers.com/Q/How_is_water_transported_throughout_the_plant

• http://www.nicksnowden.net/Module_2_Biology_pages/water_transport_in_plants.htm

• http://mason.gmu.edu/~jlawrey/biol304/biol304/potometer.gif

• http://www.nsf.gov/news/special_reports/scivis/images/transpiration_th.jpg

• http://elkhorn.unl.edu/croptechnology2005/UserFiles/Image/animThumbnails/1067618494.gif

• http://universe-review.ca/I10-24-vascular.jpg

• http://asia.cnet.com/i/r/2006/dc/39304504/water_droplets_sc.jpg