In plant tissue culture, explants are grown in a test tube under sterile conditions in a special nutrient medium. Which of the following, according to NCERT, must this nutrient medium provide?
A. A carbon source such as sucrose
B. Growth regulators like auxins and cytokinins
C. Antibiotics such as ampicillin and tetracycline
D. Inorganic salts, vitamins and amino acids
Choose the correct answer from the options given below:
Answer & explanation
Correct answer: option 1
The correct answer is Option (1) → A, B and D only
A cut piece of plant (explant) cannot make its own food in a test tube and needs signals to divide and form organs. So the medium must give it an energy source, minerals and other nutrients, and plant hormones.
A. A carbon source such as sucrose — True. Sucrose gives the growing cells the carbon and energy they need.
B. Growth regulators like auxins and cytokinins — True. These hormones control cell division and the formation of shoots and roots from the explant.
C. Antibiotics such as ampicillin and tetracycline — False. These are not part of the medium NCERT lists. Ampicillin and tetracycline are met in rDNA technology, where resistance to them is used as a selectable marker in E. coli.
D. Inorganic salts, vitamins and amino acids — True. These supply the minerals and other nutrients for growth.
NCERT Extract:
Biotechnological Applications in Agriculture – “… It was learnt by scientists, during 1950s, that whole plants could be regenerated from explants, i.e., any part of a plant taken out and grown in a test tube, under sterile conditions in special nutrient media. This capacity to generate a whole plant from any cell/explant is called totipotency. 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.”