Give 2 examples of root hair cells of plants and cells of villi in the small intestine.
- how does it achieve cellular homeostasis by different transport mechanisms?
The villus has microvilli which increase the surface area for absorption of nutrients in the intestine, making the process more efficient. Increased absorptive area allows digested nutrients, such as monosaccharide and amino acids, to pass into the partially permeable membrane of villi through diffusion. These nutrients diffuse down a concentration gradient from a region of high concentration to a region of low concentration.
The villus is specialised for absorption in the small intestine as it has a thin wall, about one cell thick, which enables a shorter diffusion path. The villus also has a rich blood supply to maintain a concentration gradient for diffusion to take place.
Hence, the villus allows digested food to be transported around the body through the bloodstream quickly.
Root hair cells in plants
Root hair cells help to increase water absorption and other minerals. In order for water to be transported via the xylem tube, it moves from root cell to root cell via osmosis.
As water moves into the root hair cell down the concentration gradient, the solution inside the root hair cell becomes more dilute. This means that there is now a concentration gradient between the root hair cell and adjacent root cells, so water moves from the root hair cell and into the adjacent cells, till it reaches the xylem tube for transport, via osmosis.
(source: http://www.bbc.co.uk/schools/gcsebitesize/science/triple_aqa/transport_systems/transport_in_plants/revision/2/ )