Tag: biology

There are five classes of naturally occurring plant growth regulator. These are auxins, gibberellins, cytokinins, abscisic acid and ethylene. Ethylene is also called as ripening hormone as it is responsible for ripening of fruits. Fruit ripening is accompanied by increase rate of respiration. Due to increased respiration, complex carbohydrates are broken down into simpler sugars and cell wall becomes soft. It inhibits cell division. It is also involved in abscission of leaves, fruits and flowers.

Ethylene is a gaseous plant hormone. It is also called as ripening hormone as it increases ripening of fruits. Fruit ripening is accompanied by increase rate of respiration. Due to increased respiration, complex carbohydrates are broken down into simpler sugars and cell wall becomes soft. It inhibits cell division. It is also involved in abscission of leaves, fruits and flowers.

Many hormone-like abscisic acid (for closing)  cytokinin (for opening) and ethylene (for opening and closing both) are responsible for opening and closing of stomata. 

Abscisic acid is a plant hormone. It is also called as stress hormone. During unfavourable environmental conditions like drought, it induces seed dormancy. When there is favaourable condition, seed dormancy is broken and germination takes place.

Ethylene and abscisic acid both are the plant hormones. Ethylene hormone is also called as ripening hormone as it helps in the ripening of fruits. Abscisic acid is also called as a stress hormone. It promotes stomatal closure when insufficient water is available in the soil. 

Abscisic acid is a plant hormone. It is also called as stress hormone as under stress environmental condition, it induces seed dormancy. It promotes stomatal closure under water stress condition to decrease the rate of transpiration.

Berry size of many seedless table grape cultivars can be substantially increased by applying gibberellic acid.

• Ethylene is a simple gaseous Plant growth hormone. It is synthesized in large amounts by tissues undergoing senescence and ripening fruits.
• Ethylene promotes senescence and abscission of plant organs, especially of leaves and flowers.
  
• Ethylene is highly effective in fruit ripening. It enhances the respiration rate during the ripening of the fruits. 
• Ethylene promotes elongation of the stem in paddy.
• Ethylene also promotes root growth and root hair formation, thus helping the plants to increase their absorption surface.
• Hence Ethylene inhibits the growth of roots is a wrong statement about ethylene.
• So, the incorrect option is 'Inhibit growth of root'.

Abscisic acid is a plant hormone which causes abscision. It never promotes flowering in plants. ABA owes its name to its role in the abscission of plant leaves. In preparation for winter, ABA is produced in terminal buds. This slows plant growth and directs leaf primordia to develop scales to protect the dormant buds during the cold season. ABA also inhibits the division of cells in the vascular cambium, adjusting to cold conditions in the winter by suspending primary and secondary growth. It also promotes dormancy in buds.

Ethylene is a simple gaseous plant growth regulator (PGR). It is synthesised in large amounts by tissues undergoing senescence and ripening fruits. Influences of ethylene on plants include horizontal growth of seedlings, swelling of the axis and apical hook formation in dicot seedlings. Ethylene promotes senescence and abscission of plant organs especially of leaves and flowers. Ethylene is highly effective in fruit ripening. It enhances the respiration rate during ripening of the fruits. This rise in rate of respiration is called as respiratory climactic.