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Roots are equal in importance to leaves as the life support system for plants.

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Roots are equal in importance to leaves as the life support system for plants. Roots are Carbon pumps that feed soil organisms and contribute to soil organic matter, Storage organs, Chemical factories that may change soil pH, poison competitors, they filter out toxins, concentrate rare elements, etc. They are sensor network that helps regulate plant growth, they are absorptive network for limiting soil resources of water and nutrients they have mechanical structures that support plants, strengthen soil, construct channels and break rocks. The epidermis is the outmost layer of roots that functions as the interface between plants and the soil. Cells of the epidermis of young roots. Epidermal cells often have narrow projections called root hairs that extend between soil particles. Root hairs may be long or short, dense, spares, or absent altogether. ...read more.


Osmosis is a special case of the diffusion of water. Osmosis occurs when water diffuses across a semi-permeable membrane. Diffusion is the movement of particles from an area of high concentration to an area of low concentration until a point of equilibrium is reached. Osmosis is important in biology because cell membranes behave like visking tubing. It is semi-permeable. Plant cells are surrounded by a cell wall. This is fully permeable to most molecules. It is also very strong and will only let the cell expand a little. Just inside the cell wall is the semi-permeable membrane. A cell in pure water will take in water by osmosis, because it will have a lower water potential than pure water outside. This causes the cytoplasm and the vacuole to swell. The cytoplasm presses out against the wall but this soon resists and presses back on the cell contents. ...read more.


This means they can't get in by passive transport, neither simple diffusion nor facilitated diffusion works. They must enter by way of a process known as active transport. We call it active because it requires energy from the cell. Active transport involves the use of proteins that don't just passively facilitate the transport of substances across the cell membrane, but require the use of cellular energy(usually ATP) to actively pump substances into or out of the cell. Active transport is used to: 1. Generate charge gradients. 2. Concentrate minerals and nutrients inside the cell that are in low concentration outside. 3. Keep unwanted ions or other molecules out of the cell that are able to diffuse through the cell membrane. In all these cases the key is that active transport uses energy to send substances against the direction they would travel by simple diffusion: that is from a region of low concentration to a region of high concentration. ...read more.

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