Monosalt toxicity and antagonism are related to hydrophilic colloids in protoplasm and protoplasmic membranes; the higher the ionic valence, the lower the concentration required to eliminate the toxic effects of the monosalt. Mineral ions, especially cations, have a tremendous influence on the physicochemical properties and physiological functions of protoplasm. When a certain ion alone, often destroy the normal state of the protoplasm and toxic effects; if in the single salt solution, add a small amount of other salts, the antagonistic effect and eliminate the toxic effects.
Operation method
Experiments on the selective uptake of mineral elements by plant roots
Principle
Plant roots have selective absorption of mineral elements, and even the cations of the same salt, but also in different proportions into the plant body, so the salts can be divided into physiologically acidic salt, physiologically alkaline salt and physiologically neutral salt. For example: ammonium sulfate, plant absorption of ammonium ions more, and stay in the soil sulfate ions in the soil solution becomes acidic, so this type of salt is called physiological acidic salt; for sodium nitrate, on the contrary, stay in the soil sodium ions in the soil more alkaline soil solution, called physiological alkaline salt. There are also some salts, such as ammonium nitrate, two ions absorbed similar amount, called physiological neutral salt. This experiment was conducted to characterize the selective uptake of mineral elements by plants by determining the change in pH in a solution.
Materials and Instruments
Corn seedlings Move 1. Prepare two solutions, A and B, according to the table below. Solution A is the equilibrium solution of the physiologically basic salt NaNo3, and solution B is the equilibrium solution of the physiologically acidic salt (NH4)SO7. For more product details, please visit Aladdin Scientific website.
MgSO4 NaNo3 (NH4)2SO4 KH2PO4 FeCl3
pH meter Precision pH paper Pipettes Triangular vials Cotton Dropper tubes Glass rods
2. Determine the pH of the solution before putting the material.
3. Take the corn seedlings pre-cultivated in quartz sand as experimental materials, choose four seedlings of the same size, carefully remove them from the quartz sand with their roots, gently wash away the quartz sand attached to the roots, and then cultivate them in the two solutions mentioned above respectively, and put two plants in each culture solution.
4. After 4-7 days of incubation, the pH was determined once more and the records were filled in the table below. How did the pH of the culture solution change during this process? Explain why. 