Minerals and Nutrients

Estimation of calcium and magnesium is done by EDTA in complexometric titration. Hexadentate ligand EDTA (ethylene diammine tetra acetate) forms metal chelates with calcium and magnesium. 

•  A neural signal reaching this junction releases a neurotransmitter (Acetylcholine) which generates an action potential in the sarcolemma. This spreads through the muscle fibre and causes the release of calcium ions into the sarcoplasm
  
• Active sites for myosin are present on actin which are masked by troponin-C in resting state. When Ca++ level increases it leads to the binding of calcium with a subunit of troponin i.e Troponin-C on actin(thin) filaments and thereby remove the masking of active sites for myosin.
  
• Utilizing the energy from ATP hydrolysis, the myosin head now binds to the exposed active sites on actin to form a cross bridge. 
• This pulls the attached actin filaments towards the centre of ‘A’ band.
  
• The ‘Z’ line attached to these actins are also pulled inwards thereby causing a shortening of the sarcomere, i.e., contraction. The myosin, releasing the ADP and P1 goes back to its relaxed state. Hence Ca$^{2+}$ is required for muscle contraction and nerve impulse transmission.
• So, the correct answer is 'Ca 2+'.

Magnesium is an important macronutrient required by plants in large quantity. Magnesium is a constituent of chlorophyll pigment and is required as an essential cofactor for all the reactions catalysed by kinase enzymes like hexokinase. Magnesium is also important for structural integrity of ribosomes. Ribosomes are the cell organelles involved in protein synthesis.

Tracer elements are radioisotopes which are used to trace the path of molecules in metabolic pathways. Thus elucidating the metabolic pathway. For example an important experiment proving that DNA carries genetic information, was based on tracer techniques. In 1952 Alfred D. Hershey and Martha Chase used radioactive phosphorus (32P) and radioactive sulfur (35S) tracers to show that when the bacterial virus (bacteriophage)T2 infects its host cell, Escherichia coli, it is the phosphorus-containing DNA of the viral particle, not the sulfur-containing protein of the viral coat, that enters the host cell and furnishes the genetic information for viral replication.

Water is basic necessity for all terrestrial forms of life.

An inorganic nutrient is essentially any compound or element that is not carbon-based, but is otherwise necessary to maintain health and optimum growth of a plant, animal, or human. Nitrogen is an inorganic nutrient that is later converted to organic forms like nitrite, nitrate or ammonia.

The body uses minerals to perform many different functions from building strong bones to transmitting nerve impulses. Some minerals are even used to make hormones or maintain a normal heartbeat. 

Potassium (K) and Chloride (Cl) ions are the primary minerals responsible for maintaining the osmotic potential and cation-anion balance within plant cells.

In plant physiology, any mineral ion concentration that reduces the dry weight of tissues by about 10% is defined as the toxic concentration.

The criteria for the essentiality of mineral elements in plants were established by Arnon and Stout in 1939.

Magnesium (Mg) is essential for the activation of enzymes involved in respiration and photosynthesis. Manganese (Mn) is also a key activator for several respiratory enzymes, including those in the Krebs cycle.

Essential elements that plants absorb from the soil in inorganic form are classified as mineral elements. Non-mineral elements like carbon, hydrogen, and oxygen are typically obtained from air and water.

Mo is a cofactor for enzyme nitrogenase, which is the most crucial enzyme for nitrogen fixation.