Read the paragraph and answer the questions:
Plant tissue culture is based on the special property of plant cells to generate a whole plant, called totipotency. The plant part used in tissue culture is called explant. The nutrient medium provides a carbon sources such as sucrose. inorganic salts, vitamins, amino acids and growth regulators like auxins cytokinins etc. Propagation of thousands of plants in very short duration through tissue culture is called micropropagation. Each of these plants will be genetically identical to the original plant i.e., they are somaclones. Another application of tissue culture is to recover virus free plants, from the infected ones. The apical or axillary meristem, which is free of virus, is removed and cultured in-vitro to obtain virus-free plants. Scientists have succeeded in culturing meristems of sugarcane, banana, potato etc. Scientists have isolated single cells from plants and after digesting their cell walls, the protoplasts were isolated. Protoplasts from two different varieties of plants - each having a desirable character - are fused to get hybrid protoplasts. These hybrid protoplasts are called somatic hybrids and the process is called somatic hybridisation. Somatic hybrids are further grown to form a new plant. Protoplast of tomato is fused with that of potato, to form new hybrid plants called Pomato. Pomato unfortunately did not have all the desired combination of the two plants.
Protoplasts are obtained by digestion of _____of the cells.
Answer & explanation
Correct answer: option 3
The correct answer is Option (3) → cell walls
A protoplast is a plant cell whose cell wall has been removed, leaving the living cell inside its plasma membrane. The passage says the protoplasts were isolated after digesting their cell walls.
Option (1) Nuclei — Incorrect. The nucleus must stay; a protoplast is a living cell that can grow into a plant.
Option (2) Plasma membranes — Incorrect. The plasma membrane is the boundary of the protoplast itself; digesting it would kill the cell.
Option (3) cell walls — Correct. Enzymes digest the cell wall, and the protoplasts of two plants can then be fused.
Option (4) Proteins — Incorrect. The cell’s proteins are needed for its life; they are not removed.
Note: The passage is taken from NCERT. NTA has put lines of the NCERT text together to make it. Most CUET (UG) questions come straight from NCERT, so study the book line by line, including figures and their titles.