Question

How nutrients are absorbed by plants?

Answer 1

Nutrient uptake by plants:

1. Minerals must be dissolved in water for absorption.
2. The roots of plants allow for mineral absorption.
3. The number of minerals absorbed increases with the surface area of the roots.
4. There are two ways that minerals are absorbed.
5. Mineral absorption that occurs without active effort is known as passive mineral absorption.
6. It happens by simple diffusion along the concentration gradient, that is, from one area of higher concentration to another area of lower concentration.
7. Mineral absorption involves active participation and ATP consumption (Adenosine triphosphate).

There are three main mechanisms of mineral absorption:

Ion exchange:

1. In this technique, the ions that have been adsorbed on the surface of the root can exchange with other ions from the soil solution that have the same charge.
2. For instance, potassium ions in the soil can exchange hydrogen ions that have been deposited on the surface of root cells.

Carrier concept:

1. This idea states that some ions pass through the plasma membrane fully unperturbed.
2. Carrier proteins are specialized proteins on the plasma membrane that promote the absorption of certain ions.
3. Here, the ions first join with the carrier protein to create a complex called a carrier-ion.
4. Crossing the plasma membrane is the carrier-ion complex.
5. It releases the ions into the cell lumen when it reaches the inner surface of the membrane.
   

Donnan equilibrium:

1. In accordance with this idea, certain ions known as diffusible ions or fixed ions are present inside the root cells.
2. These ions do not pass through the plasma membrane and diffuse outside.
3. A cell that possesses cations as fixed ions can take up anions from the soil to keep the electrical potential in balance.
4. The equilibrium between anions and cations is brought about by anions being absorbed.
5. The root cells can absorb any mineral in its ionic form by achieving equilibrium.