Test: Development and Growth Regulators (July 18) - NEET MCQ

Geocarpy refers to the ripening of fruits underground, In the case of ground nut, the young fruits are pushed into the soil as a result of post-fertilisation curvature of the stalk.

Ethylene is a gaseous hormone. It aids in ripening of climacteric fruits and dehiscence of dry fruits. Climacteric fruits are the fleshy fruits which show a sudden sharp rise of respiration rate at the time of ripening (respiratory climacteric). They are usually transported in green or unripe stage. Ethylene is used to induce artificial ripening of these fruits e.g., Apple, Mango, Banana, etc.

Cytokinins are a group of hormones that promote cell division in plant roots and shoots and the growth of buds. Coconut milk is at times used in some tissue culture medium as it is rich in cytokinins.

Ratio of cytokinins to auxins controls differentiation. If both of these are present in equal quantities, the cells divide but fail to differentiate. If there is more cytokinin than auxin, shoot buds develop. If there is more auxin than cytokinin, roots develop.

Scarification involves weakening, opening otherwise altering the coat of a seed to germination. Scarificationis often done mechanically, thermally, and chemically. The seeds of many plant species are often impervious to water and gases, thus preventing or delaying germination.

The hormones that delay senescence must decrease while the ones that speed up the aging process must increase. Cytokinins are one group of senescence delayers. These hormones are involved in cell growth, and high levels can help prevent senescence.

‘Foolish seedling’ of rice led to the discovery of GA.

Foolish seedling disease or Bakanae disease is a disease of rice seedlings, which was caused by a fungal pathogen . Kurosawa reported the appearance of symptoms of the disease in uninfected rice seedlings when they were treated with sterile filtrates of the fungus. The active substances were later identified as Gibberellic acid.