What are trace elements? Give examples and characterize the biological significance of these elements.

There is a large group of chemical elements that are found in organisms in very low concentrations. These are aluminum, copper, manganese, zinc, molybdenum, cobalt, nickel, iodine, selenium, bromine, fluorine, boron and many others. Each of them accounts for no more than thousandths of a percent, and the total contribution of these elements to the cell mass is about 0.02%. Microelements come to plants and microorganisms from the soil and water, and to animals – from food, water and air. The role and functions of the elements of this group in various organisms are very diverse. As a rule, microelements are part of biologically active compounds (enzymes, vitamins and hormones), and their effect is manifested mainly in the way they affect metabolism. Cobalt is part of vitamin B12 and takes part in the synthesis of hemoglobin, its deficiency leads to anemia.
Molybdenum in the composition of enzymes is involved in the fixation of nitrogen in bacteria and ensures the functioning of the stomatal apparatus in plants.
Copper is a component of the enzyme involved in the synthesis of melanin (skin pigment), affects the growth and reproduction of plants, and blood formation processes in animal organisms.
Iodine in all vertebrates is part of the thyroid hormone – thyroxine. Boron affects the growth processes in plants, its lack leads to the death of apical buds, flowers and ovaries.
Zinc acts on the growth of animals and plants, and is also part of the pancreatic hormone – insulin.
For example, manganese improves the absorption of copper by the body, and fluorine affects the metabolism of strontium. It was found that some organisms intensively accumulate certain elements.
For example, many algae accumulate iodine, horsetails – silicon, buttercups – lithium, and mollusks are characterized by a high copper content.
Trace elements are widely used in modern agriculture in the form of micronutrient fertilizers to increase crop yields and as feed additives to increase animal productivity. Trace elements are also used in medicine.

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