Root hair cells are found near the tips of roots. Their job is to take in water and mineral ions from the soil. Each one has a long, thin extension called a root hair that sticks out into the soil. This gives the cell a very large surface area, so more water and mineral ions can be absorbed at once. The thin shape also means the distance for substances to travel is short.
Water enters by osmosis. The cell sap in the large vacuole is more concentrated than the water in the soil, so water moves from the dilute soil water into the cell sap.
Mineral ions are usually at a lower concentration in the soil than inside the cell. The cell takes them in by active transport, which moves them against the concentration gradient. This needs energy from respiration, so root hair cells have many mitochondria. They have no chloroplasts, because roots are underground and get no light.
