Question

The hormone which was discovered through foolish seedling disease of rice is_____
A)Indole-3-acetic acid
B)Ethylene
C)Gibberellic acid
D)Kinetin

Answer 1

Hint: Plants have different hormones which are known as phytohormones, these are chemical compounds that are present in very low concentrations in the plant and help in the different growth and developmental processes in the plants.

Complete answer:
 Many plant hormones act as growth activators whereas there are plant hormones that also act as growth inhibitors. The five major plant hormones are- indole-3-acetic acid or auxin, cytokinin, gibberellic acid, ethylene and abscisic acid. Among the above mentioned five hormones, auxin, cytokinin and gibberellic acid acts as plant growth promoter thus helping in the growth of plants.

Abscisic acid acts as plant growth inhibitor and ethylene can act either as plant growth promoter or inhibitor. Kinetin is a cytokinin which helps in plant growth. Foolish seedling disease of rice is a fungal disease that is caused by the fungus Gibberella fujikuroi whose metabolism produced the plant hormone gibberellic acid. The rice plants affected by the fungus were etiolated and chlorotic and did not produce any edible grains. So the hormone isolated from foolish seedling of rice is gibberellic acid.

Hence, the correct answer is option (C)

Note: Gibberellic acid is a very potent plant growth hormone. They play a number of roles in the development of plants, they stimulate both root and stem growth, they are known to induce mitotic division in leaves of some plants and they also increase seed germination rates in plants.