Test: Plant Hormones - UPSC MCQ

In the wooden plants, the activity of cambium is increased by the Gibberellins. The endosperm is the site of Gibberellins synthesis. After synthesis Gibberrellins are transported to the plant by phloem and Gibberellins which synthesize in roots are transported to shoots by xylem.

The correct answer is D: None of the above.

The plant hormone that is formed in injured cells to aid in the healing process is called auxin. Auxin is responsible for promoting cell division and elongation, which helps in the regeneration of damaged tissues and the formation of new roots. It plays a crucial role in wound healing and is synthesized in the meristem tissues near the injured area.

The correct answer is B: Gibberellin.

Gibberellins are plant hormones that play a key role in breaking seed dormancy and promoting seed germination. They stimulate various physiological processes in plants, including stem elongation, leaf expansion, and flowering. In the context of seed dormancy, gibberellins are responsible for initiating the growth of the embryo and promoting the synthesis of enzymes that break down stored nutrients in the seed, allowing it to sprout and begin its growth cycle.

Cytokinins are involved in cell division and differentiation in plants. They promote cell division and play a crucial role in regulating the growth and development of plant tissues. Cytokinins stimulate the synthesis of RNA and proteins, which are essential for cell division and growth. By promoting these processes, cytokinins contribute to the overall growth and development of plants.

Ethylene is the plant hormone that is found in gaseous form. It is the only gaseous hormone among the options listed. Ethylene plays a significant role in various aspects of plant growth and development, including fruit ripening, leaf senescence (aging), and the response to environmental stresses.

Ethylene is produced naturally by plants and is released as a gas into the surrounding environment. It can diffuse through the air and affect nearby plants and tissues. The gaseous nature of ethylene allows it to act as a signal molecule, triggering physiological and developmental changes in plants.

Florigens, abscisic acid, and auxin are not gaseous hormones. Florigens are transported through the phloem, abscisic acid is a soluble hormone, and auxin is a soluble hormone that can be transported through the plant's vascular system.

Cytokinins are plant hormones that work in conjunction with auxins to promote cell division and development. Auxins primarily stimulate cell elongation, while cytokinins specifically stimulate cell division. When cytokinins are present along with auxins, they promote the growth of lateral buds, enhance shoot formation, and stimulate the development of roots.

The interaction between auxins and cytokinins is crucial for various processes in plant development, including the formation of new tissues, the growth of shoots and roots, and the overall coordination of plant growth and development.

On the other hand, ethylene is not directly involved in cell division but is primarily associated with fruit ripening and other processes. Florigens, as mentioned before, are hormones that induce flowering and are not directly related to cell division and development.

Florigens are the plant hormones that are formed in leaves and play a key role in the blooming or flowering of plants. They are responsible for initiating the transition from the vegetative phase to the reproductive phase in plants, leading to the formation of flowers.

Florigens are specifically involved in promoting the initiation of flowering in response to various environmental and internal cues, such as day length and age of the plant. They are synthesized in the leaves and then transported to the apical meristem, where they induce the development of floral structures.

Neither traumatic nor auxin hormones are directly associated with the blooming of flowers. Traumatic hormone is not a recognized plant hormone, and auxin primarily plays a role in various aspects of plant growth and development, but not specifically in flowering.

Auxins are not specifically produced at the region of elongation. Instead, they are primarily synthesized in the apical meristems of the plant, particularly in the shoot apical meristem and young leaves. From there, auxins are transported downwards towards the region of elongation, where they play a crucial role in cell elongation and growth. So, while auxins are involved in the regulation of elongation, they are not produced exclusively at the region of elongation.

Ethylene is the plant hormone responsible for the ripening of fruits. It is a gaseous hormone that is naturally produced by plants during various stages of their development, including fruit ripening. Ethylene acts as a signal to initiate and accelerate the ripening process in fruits by triggering changes in color, texture, aroma, and taste.

During fruit ripening, ethylene promotes the breakdown of chlorophyll, which leads to changes in pigmentation. It also stimulates the production of enzymes that break down complex carbohydrates into simpler sugars, resulting in the sweetening of fruits. Additionally, ethylene affects the softening of fruit tissues by breaking down cell walls and pectins, leading to a softer and juicier texture.

While auxin, cytokinins, and other plant hormones have important roles in various aspects of plant growth and development, ethylene is specifically associated with fruit ripening.

Auxin is a plant hormone that plays a crucial role in various aspects of plant growth and development, including preventing the abscission or shedding of leaves, flowers, and fruits. It helps in maintaining the attachment of these structures to the plant, thereby saving the crops from falling off prematurely.

While the other hormones mentioned in the options also have important roles in plant physiology, auxin specifically helps in preventing the loss of crops by promoting cell elongation, which aids in keeping the plant parts firmly attached.