31 Years NEET Previous Year Questions: Mineral Nutrition - 2

Along with water, minerals move upwards through the trachaery elements of xylem.

Potassium is not a constituent of any enzyme but is an activator of enzymes. Potassium is an essential mineral and is found in more amounts in actively dividing cells such as of buds young leaves, root tips, etc. It has some other roles like involved in regulating stomated movement and protein synthesis.

Symbiotic relationship between roots of higher plants and fungi is called mycorrhiza, e.g. Pinus roots associated with fungal hyphae.

In lichens, the association between an algae and a fungus is considered to be a symbiotic one. In this association, algae provides food to fungi.

Anabaena is a nitrogen fixing blue-green alga composed of barrel-shaped cells held in a gelatinous matrix. So it can fix atmospheric nitrogen.

Nutrients which are required in large amounts and functioning of plant are known as macronutrients eg. Ca, Mg, N. Nutrients required in trace amounts are known as micronutrients. Manganese is a micronutrient for plants essential for synthesis of chlorophyll. It is also required for activation of enzymes of respiration and nitrogen metabolism.

Iodine is the only such element which is an essential mineral for animals but is not required by plants.

Etiolation is a plant response to stimuli. When plant seeds are grown in insufficient light, either in partial or complete absence of light, the seedlings will have long, weak stems, smaller and fewer leaves because of longer internodes, and a pale yellow colour (chlorosis). This is due to a lack of chlorophyll. The plant’s increase in height helps it to reach a possible source of light faster.

Rhizobium is a symbiotic nitrogen fixer. Azospirillum is a nitrogen fixing fungus and Nostoc is anaerobic.

Insectivorous plants  supplement the supply of nitrogenous food by capturing and digesting insects. Pitcher plant (Nepenthes) and bladderwort (Utricularia)  are both insectivorous plants.

Nitrogen is the constituent of amino acids, proteins, nucleic acids, nucleotides coenzymes, hexoamines etc. Deficiency of nitrogen repidly inhibits the plant growth and yellowing of the leaves (chlorosis) magnesium has the specific role in the activation of enzymes, taking part in photosynthesis, respiration. It also forms a part of the ring structure of the chlorophyll molecule. Deficiency of Mg causes chlorosis i.e., yellowing of leaves. Deficiency of both Nitrogen and Magnesium causes chlorosis (yellowing of leaves). Thus a plant growing in magnesium-deficient soil would show chlorosis inspite of being sprayed with urea (nitrogen).

A molecule of N2 is changed to ammonia by nitrogenase. Transaminase transfers amino group from one substrate to another.

Roots do not spend any energy on this type of mineral  absorption. So application of a metallic inhibitor will not retard the process.

Azolla performs nitrogen fixation through its colonies of Anabaena azollae, which have the capacity to fix atmospheric nitrogen.

(i) Essential elements as components of biomolecules and hence structural elements of cells.
(ii) Essential elements that are components of energy-related chemical compounds in plants.
(iii) Essential elements that activate or inhibit enzymes.
(iv) Some essential elements can alter the osmotic potential of a cell.

These are all insectivorous plants.

Minor elements are those which are required by plants in very small amount. These elements have a significant role in enzyme activities (zinc activates carboxylases, carbonic anhydrase and various dehydrogenases).

Molybdenum is a component of nitrogenase and nitrate reductase involved during N₂ fixation. Copper is essential for photosynthesis and respiration. Zinc is involved in synthesis of auxin. Manganese is activator of enzymes involved in nitrogen metabolism

The major portion of the dry weight of plants comprises of Carbon, hydrogen and oxygen

Manganese is an activator of enzymes. Copper is essential for photosynthesis. Molybdenum is a cofactor of enzymes. Boron assists in sugar transport.

Grey spots of oat are caused by deficiency of Manganese(Mn).

 The freshwater fern Azolla harbours Anabaena (a blue green alga) in  its leaf cavities. Chlorella is simply a green alga.  Nostoc is a free living cyanobacteria involved in N₂ fixation and  so is Tolypothrix.

Copper : Electron transfer Maintenance of carbohydrate / nitrogen balance, chlorophyll synthesis.
Iron : Electron  transport in photosynthesis and respiration development of chloroplasts, chlorophyll and other pigments, protein synthesis.
Manganese : Metabolism and photolytic evolution of oxygen.

A plants require magnesium for chlorophyll synthesis. All four rings bind with metal atom magnesium (Mg++ ), which remain present at the center of chlorophyll molecule.