Tag: biology

Ethylene hormone in plants helps in ripening of fruits. Abscisic acid is known for its inhibiting nature in growth. It causes bud dormancy in several plants. It also causes closure of stomata to minimize the loss of water by transpiration.

ABA is a plant hormone which is inhibiting in nature. It causes the closure of stomata, in order to reduce the rate of transpiration and the loss of water thereby. It is also well known for its dormant activity. ABA promotes early aging in the plant and also inhibits flowering, fruiting, germination, etc. 

Human urine - auxin. Human urine commonly shows the presence of Indole acetic acid, compound having similar properties to that of auxin.It was first discovered in 1931 by Kogl and Haagen Smit, five years earlier the discovery of auxins.
Gibberella fujikori - Gibberellin. G.fujikori is a fungal plant pathogen. It causes bakane disease in rice seedlings, by overloading them with the phytohormone; gibberellin as its own metabolic product.
Herring fish DNA - cytokinin. Cytokinins were first discovered in 1955 as promoters of cell division in the DNA of Herring sperm. Since, that discovery many different compound with cytokinin activity have been discovered, both natural and synthetic (diphenyurea).
Ripening fruits - ethylene. Ethylene is the only phytohormone present in gaseous state. It helps in inducing early ripening when sprayed to fruits.
Aged leaves of plants - ABA. Abscissic acid promotes the early aging of leaves, also called as senescence. Aging, dormancy of buds, inducing stomatal closure, inhibiting fruit ripening, etc, are the functions of ABA.

Senescence is a programmed developmental process. Leaf abscission is a classic example of programmed cell death and senescence in plants, allowing the plant to shed older or damaged leaves.

Antitranspirants are compounds applied to the leaves of plants to reduce transpiration. Some examples are phenylmercury acetate, abscisic acid (ABA), and aspirin (acetyl salicylic acid). ABA is a well-known antitranspirant.
Thus, the correct answer is an option (D). 

ABA is Abscisic acid. It is a plant hormone. In formation of winter buds, ABA is produced in terminal buds. It helps the conversion of the apical meristem into a dormant bud.

There are various plant hormones which act as growth regulators. Hormones like gibberellic acid (GA), Indoleacetic acid (IAA), a type of auxin, cytokinin (CK) are growth promoter. Hormones like Abscisic Acid (ABA), ethylene are growth inhibitor. These hormones accelerate abscission process.

 It inhibits root elongation, stem elongation and seed germination. It brings out the stomatal closure when soil water is insufficient to keep up with transpiration. It binds to receptor present on the guard cells and hence closes stomata.

Abscisic acid is a plant hormone. It is involved in various physiological processes of the plant. It acts as a plant growth inhibitor. It is also called as stress hormone as its concentration increases during stress condition. Under the unfavourable condition, it induces seed dormancy. When favourable condition returns, seed dormancy is broken. 

Stress hormone is a hormone produced during adverse environmental conditions. Abscisic acid (ABA) is called as stress hormone. Due to this hormone, plants respond to stresses conditions like cold, drought. It increases the tolerance of plants toward various stresses. It is found in high concentration in roots during drought and later translocated to leaves. It causes stomatal closure during water stress. It also promotes seed dormancy under adverse condition.