Explants are grown using special nutrient media in tissue culture tec…

The correct answer is Option (2) → Vitamins, inorganic salts, amino acids, auxin, cytokinin, sucrose.

In tissue culture an explant (a piece of a plant) is grown in a test tube, under sterile conditions, in a special nutrient medium. The medium has to give the explant a carbon source, inorganic salts, vitamins, amino acids and growth regulators such as auxins and cytokinins.

(1) Glucose, organic salts, auxins, gibberellins, amino acids — Incorrect. The carbon source is sucrose, not glucose. The salts are inorganic, and vitamins and cytokinins are missing.

(2) Vitamins, inorganic salts, amino acids, auxin, cytokinin, sucrose. — Correct. It names sucrose as the carbon source, together with inorganic salts, vitamins, amino acids and the two growth regulators.

(3) Sucrose, organic salts, amino acids, auxin, cytokinin — Incorrect. Sucrose is right, but the salts should be inorganic and vitamins are missing.

(4) Glucose, organic salts, vitamins, auxin, cytokinin — Incorrect. The carbon source should be sucrose, and the salts should be inorganic.

Note: It seems that there is a mistake in the original NTA paper, which prints “The correct source of carbon in this nutrient medium is” when it should read “The correct composition of this nutrient medium is”, because every option lists several ingredients and not only a carbon source.

NCERT Extract:
Biotechnological Applications in Agriculture – “… You will learn how to accomplish this in higher classes. It is important to stress here that the nutrient medium must provide a carbon source such as sucrose and also inorganic salts, vitamins, amino acids and growth regulators like auxins, cytokinins etc.”