Question

Which one of the following is not a micro-element for plants?
A) Cu
B) B
C) Zn
D) Cr

Answer 1

Hint:The analysis of the chemical elements and compounds required for plant growth, plant metabolism, and their external supply is plant nutrition. The plant is unable to complete a normal life cycle in its absence, or that the element is part of some essential constituent or metabolite of the plant.

Complete answer:
Seventeen different elements are included in the total vital plant nutrients: carbon, oxygen and hydrogen that are absorbed from the air, while other nutrients, including nitrogen, are usually derived from the soil (some parasitic or carnivorous plants are exceptions).
From its rising medium, plants must derive the following mineral nutrients:-
Macronutrients
Nitrogen (N ), phosphorus (P ), potassium (K ), calcium (Ca), sulphur (S), magnesium ( Mg), carbon (C ), oxygen (O), hydrogen (H)
Micronutrients (or trace minerals)
Iron (Fe), boron (B), chlorine (Cl), manganese (Mn ), zinc (Zn ), copper (Cu), molybdenum ( Mo), nickel ( Ni)
Such elements exist as salts under the surface, so plants absorb these elements as ions. The macronutrients are consumed in greater quantities; on a dry matter weight basis, hydrogen, oxygen, nitrogen and carbon contribute to over 95 percent of the entire biomass of a plant.
In plant tissue, micronutrients are found in amounts calculated in parts per million, varying between 0.1 and 200 ppm, or less than 0.02 percent dry weight. Plants are able to collect most trace elements adequately. Some plants are sensitive measures of the chemical atmosphere in which they grow and some plants have barrier structures that exclude or restrict the absorption of a specific element or ion species, e.g. alder twigs typically absorb molybdenum but not arsenic, while the spruce bark system along with the enclosed groundwaters is the opposite.

The correct answer is option(D) Cr.

Note:Without adding nutrients as fertiliser, most soil conditions around the world can provide plants adapted to that environment and soil with ample nutrition for a complete life cycle. If the soil is cultivated, however, it is important to artificially alter soil fertility by adding fertilizer to encourage vigorous growth and increase or maintain yield. This is done because nutrient deficiency can restrict growth and crop yield, even with sufficient water and light.