Cambridge O Level Biology · Syllabus 5090 · Transport in Flowering Plants
Root Hair Cell
What is Root Hair Cell?
A specialised epidermal cell of a young plant root that bears a long, narrow, hair-like projection extending between the soil particles. The projection greatly increases the surface area in contact with the soil solution, the thin cell wall gives a short pathway for substances to cross, the partially permeable cell membrane allows water to enter by osmosis, the large vacuole holds cell sap that keeps the water potential of the cell below that of the soil solution, and numerous mitochondria release the energy from respiration that is needed for the active transport of mineral ions.
This definition is part of the Transport in Flowering Plants chapter in Cambridge O Level Biology.
Common mistakes with Root Hair Cell
- 1. “Water is taken into the root by active transport.” Why wrongActive transport moves particles against a concentration gradient using energy. Water never needs that: it moves down a water-potential gradient by itself. WriteWater enters the root hair cell by osmosis, from the soil solution of higher water potential to the cell sap of lower water potential, through the partially permeable cell membrane.
Questions students ask about Root Hair Cell
Why is a root hair cell adapted for absorbing water?
Its long, narrow projection gives a large surface area in contact with the soil solution; its cell wall is thin, so the pathway is short; its cell membrane is partially permeable, so osmosis can occur; and the solutes in its large vacuole keep the water potential of the cell below that of the soil solution, maintaining the gradient that draws water in.