Question

Define root system. Give two functions of roots.
please long answer​

Answer 1

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Roots perform the following functions: Roots absorb water and nutrients from the soil. They anchor the plant firmly. They help in storing food and nutrients. Roots transport water and minerals to the plant.

Answer 2

Roots absorb water and nutrients from the soil. They anchor the plant firmly. They help in storing food and nutrients. Roots transport water and minerals to the plant.

Root systems fulfil quite a number of fascinating and not yet fully understood functions, in addition to their well known ones of growing down and horizontally outward in every direction to provide plant stability, of taking up water and inorganic nutrients in support of the growth and survival of the above-ground shoot system, and of storing materials such as starch and lipid.

Long ago it was shown that exposure of leaves to 14CO2 resulted in about 60% of the radio-labeled (14C) products of photosynthesis (mostly sugar) being translocated via the phloem to the root tips where a large proportion of the 14C-labeled material was exuded into the surrounding soil (the 'rhizosphere') as food to support symbiotic microorganisms (bacteria, fungi) which aid in providing the root tips with inorganic nutrients and water for uptake and which prevent injurious organisms from attacking the root tips. Some researchers also believe the exudate from root tips includes excretion metabolites in order to cleanse the plant of noxious compounds, but that's still more hypothesis than fact. However, it is well established that roots of many plant species exude organic compounds, known as allelopathic substances, that inhibit germination and growth, thus preventing other plants from invading their soil domain.

In addition to root exudation of organic substances, the 14C in photosynthetically produced sugar after translocation to the roots is metabolized into amino acids, in particular into L-glutamine and L-asparagine (nitrogen enriched aa's), which then move upward via the xylem transpiration stream to the leaves, growing shoots, reproductive organs and cambium in support of their metabolism and growth.

A little known aspect of roots is their ability to utilize CO2 in soil water (more CO2 dissolves in cold than in warm water) and, using enzymes different from those used in photosynthesis as catalysts, to incorporate that carbon into organic molecules in the absence of light. Precisely how important this 'dark fixation' of CO2 is, relative to photosynthetic CO2 fixation, remains to be thoroughly researched.

Roots biosynthesize organic molecules known as phytohormones that are exported to the shoot system and regulate the growth and development of the shoot system and help it to survive environmental change. Two of the better known phytohormones produced by roots are cytokinins and abscisic acid (ABA), and the ethylene (another phytohormone) precursor 1-aminocyclopropane-1-carboxylic acid (ACC) also can originate in roots and move via the xylem to the shoot system.

Shoot cuttings from woody plants when grown in water with inorganic nutrients but without roots will sometimes produce a small amount of wood through cambial activity; however, when roots are present the cambium grows much more strongly such that much more wood is produced. The explanation for this evidently resides in the role of roots in exporting phytohormones and ACC to the shoot system.