How do plants absorb their nutrients?
http://en.wikipedia.org/wiki/Cellular_respiration From another site I copied this: The nutrient uptake process. Uptake of nutrients by a plant root is an active process. As water is taken up to support transpiration, nutrients may be moved to the root surface through mass flow. But they are not taken directly into the root. The plasma membrane of the endoderm blocks the movement of ions into the root. At this point an active uptake process which requires energy is used to move the nutrients into the root and xylem for transport to the growing tissues. A specific protein carrier is used to bind with a nutrient ion and carry it across the membrane. This active uptake process is a selective process. The root discriminates and only expends energy to take up nutrients it needs. Thus nutrient uptake is not proportional to the ratios of nutrients in the soil solution. Ions in large supply in the soil solution, such as calcium and
