Read the passage and answer the following questions:
The Green Revolution successfully increased food production by threefold, but it still couldn't meet the demand of the growing human population. The increased yields were partly due to the use of improved crop varieties, but mainly due to better management practices and the use of agrochemicals such as fertilisers and pesticides. However, farmers in the developing world often find agrochemicals too expensive, and further improvements in yield using conventional breeding methods become challenging. To address the limitations of traditional breeding techniques, scientists developed a technology called tissue culture. Tissue culture involves the regeneration of whole plants from small plant parts (explants) that are grown in a controlled environment, such as a test tube, with specific nutrient media. This ability of explants to regenerate into whole plants is known as totipotency. The nutrient medium used in tissue culture contains carbon sources like sucrose, inorganic salts, vitamins, amino acids, and growth regulators like auxins and cytokinins. By utilising tissue culture techniques, a large number of plants can be propagated rapidly and efficiently, a process known as micro-propagation. These plants are genetically identical to the original plant from which the explants were obtained, making them somaclones. Many important food plants, such as tomato, banana, and apple, have been commercially produced using tissue culture. Another significant application of tissue culture is the recovery of healthy plants from diseased ones. Even if a plant is infected with a virus, the meristem (apical and axillary) regions remain free of the virus. Scientists can remove the virus-free meristem and grow it in vitro to obtain virus-free plants.
Scientists have succeeded in culturing the meristems of which of the following groups of plants to obtain virus-free plants?
Answer & explanation
Correct answer: option 1
The correct answer is Option (1) → Banana, sugarcane and potato
Even in a plant infected with a virus, the meristem (apical and axillary) is free of virus. So the meristem is removed and grown in vitro to obtain virus-free plants. Scientists have succeeded in culturing the meristems of banana, sugarcane and potato in this way.
Option (1) Banana, sugarcane and potato — Correct. Banana, sugarcane and potato are the plants whose meristems have been cultured to get virus-free plants.
Option (2) Tomato, banana and apple — Incorrect. Tomato, banana and apple are the food plants produced on a commercial scale by micro-propagation, not the group named for meristem culture.
Option (3) Cotton, corn and soyabean — Incorrect. Cotton, corn and soyabean are examples of Bt crops, made pest-resistant with Bt toxin genes.
Option (4) Rice, tomato and potato — Incorrect. Rice, tomato and potato are named in the book among the crops into which the Bt toxin gene has been put. Of these, only potato is named for meristem culture.
NCERT Extract:
Biotechnological Applications in Agriculture – “Another important application of the method is the recovery of healthy plants from diseased plants. Even if the plant is infected with a virus, the meristem (apical and axillary) is free of virus. Hence, one can remove the meristem and grow it in vitro to obtain virus-free plants. Scientists have succeeded in culturing meristems of banana, sugarcane, potato, etc.”