Phosphate ions are a component of cell membranes, certain proteins, all nucleic acids and nucleotides, it is involved in energy transfer such as ATP and ADP. It activates coenzymes for amino acid production used in protein synthesis; and it is involved in many other metabolic processes required for normal growth, such as photosynthesis, glycolysis, respiration, and fatty acid synthesis.
Potassium ions helps to determine an anion-cation balance in cells and activates enzymes to metabolize carbohydrates for the making of amino acids and proteins. It is required for the opening and closing of stomata, activation of enzymes and maintaining cell turgor. Potassium facilitates cell division and growth by helping to move starches and sugars between plant parts.
These ions are extremely important to plants; if there is a deficiency in any of the ions it will stunt the growth of the plant.
20. In this question, I will be talking about the movement of the mineral ions through the soil to the roots.
Plant roots are able to absorb minerals somewhat selectively, enabling the plant to accumulate essential elements that may be present in the soil in very little quantities. In most plants, the roots absorb mineral ions when it is dissolved in water to form a solute.
There are 3 different methods and those are:
Diffusion, Mass flow and via fungal hyphae
Diffusion is movement of ions within water films that exist around soil particles, it is the driving force being the ion concentration gradient, always moving from an area of high concentration to an area of lower concentration. Most ions in solution are moved by diffusion, the movement occurring in very short distances around and between the soil particles.
Mass flow takes place when water flows through the soil. Minerals dissolves in water and form hydrogen bonds with water such that the movement of water towards the root 'drags' the minerals with the water. It carries mineral with it in solution. The mass flow of the solutions of mineral ions towards the root 'concentrates' them for absorption. As the water flows through the soil, a gradient of hydrostatic pressure is generated by the uptake of water at the roots. The water and the solutes are literally sucked up in the roots.
Via Fungal hyphae
Some ions move through the soil very slowly by diffusion and mass flow, because the ions bind to the surface of soil particles. To solve this problem, some plants have developed a relationship with a fungus. The fungus grows on the surface of the roots and sometimes even into the cells of the root. The thread-like hyphae of the fungus grow out into the soil and absorb mineral ions from the surface of soil particles. These ions are supplied to the roots, allowing the plant to grow successfully in mineral-deficient soils. This relationship is found in many trees, in members of the heather family and in orchids. This relationship is mutualistic because the fungus provides the plant with mineral ions and in return, the fungi receive sugars from the plant.
21. Why do mineral ions need to be taken up by active transport in the roots?
Active transport is taking in substances even when there is a higher concentration of the substance inside the cell than outside it. The substance is absorbed against the concentration gradient using energy supplied by ATP.
Mineral ions need to be taken up by active transport in the roots because the nutrient concentration in the plant is very high compared to that in the soil, so the process of diffusion would be inadequate, hence the importance of active transport, enabling the plant to take in more nutrients even though it has a higher concentration of nutrients than the soil. Simply, if active transport was not available, nutrients would be lost rather than absorbed, and plants would not be able to survive.
