Question

Read the given statements and select the correct option. statement 1: Elongation of reduced stem is possible due to application of gibberellin hormone. statement 2: Gibberellin stimulates cell division and cell elongation. (a) Both statements 1 and 2 are correct and statement 2 is the correct explanation of statements 1. (b) Both statements 1 and 2 are correct but statement 2 is not the correct explanation of statements 1. (c) statements 1 is correct and statements 2 are incorrect . (d) Both statements 1 and 2 are incorrect and

Short answer

Both statements 1 and 2 are correct, and statement 2 is the correct explanation of statement 1. (a)

Step-by-step solution

Verify Statement 1

Check the validity of statement 1 by referring to knowledge on plant hormones. Gibberellin is known to cause the elongation of stems, particularly in dwarf or reduced stem plants. It can artificially stimulate growth when applied to these plants.

Verify Statement 2

Assess statement 2 with regards to the known functions of gibberellins. Gibberellins are indeed involved in stimulating both cell division, mostly in cambial cells, and cell elongation, particularly in stem and leaf cells.

Determine the Relationship

Examine if statement 2 is a correct explanation for statement 1. Since gibberellins stimulate cell division and elongation and this is how they lead to the elongation of a reduced stem, it appears that statement 2 is the correct explanation for statement 1.

Key concepts

Understanding Plant Hormones

Plant hormones, also known as phytohormones, play an incredibly influential role in the regulation of plant growth and development. These organic compounds, produced in low concentrations, can elicit significant physiological responses. One of the key phytohormones is gibberellin, which specifically impacts a variety of processes such as seed germination, stem elongation, and fruit maturation.

Gibberellin functions by stimulating the synthesis of certain proteins that are directly involved in plant growth. This hormone can offset the growth limitations imposed by genetic factors or environmental conditions. For example, in dwarf or reduced stem plants, the application of gibberellin can promote stem elongation, thereby bypassing natural constraints and maximizing the plant's growth potential.

Moreover, plant hormones are often involved in responses to environmental stimuli, ensuring that plants adapt effectively to changes such as light availability, temperature fluctuations, and water supply. Their precise role in these complex signaling pathways underscores the interconnected nature of plant hormonal systems and development.

Gibberellin and Stem Elongation

Stem elongation is a critical process in plant growth as it determines the plant's ability to compete for sunlight and spread its leaves for photosynthesis. Gibberellins are directly linked to this process, particularly by influencing the extension of stems. When gibberellins are present, they activate enzymes that weaken the cell walls. This weakening allows the cells to expand, a prerequisite for stem elongation.

Gibberellin's role in promoting stem elongation is especially evident in plants with a genetic predisposition for reduced growth, such as certain dwarf varieties. When these plants are treated with gibberellins, significant growth can be observed, showcasing the hormone's potent effects in overriding genetic limitations.

This hormone, therefore, serves as an essential growth regulator, favoring vertical growth to optimize exposure to light and contributing to a plant's overall ability to thrive. The precise control and artificial application of gibberellins have broad implications for agricultural practices, allowing for the manipulation of crop height and the improvement of yield.

Gibberellin-Driven Cell Division

While gibberellins are commonly associated with stem elongation, they also play a significant role in promoting cell division, particularly in the cambial region—a layer of cells located between the xylem and phloem. This region is crucial for the continuous growth and thickening of stems and roots.

The hormones stimulate the cambial cells to divide and produce more cells, contributing to the overall increase in plant mass. This increased cell division, in turn, complements the process of elongation, resulting in a longer and thicker stem. Furthermore, gibberellins are involved in the growth and elongation of leaf cells, which supports the development of larger leaves capable of more efficient photosynthesis.

While gibberellins promote cell division, other hormones like cytokinins and auxins also contribute to this essential function, demonstrating again how various hormones interact to regulate precise developmental patterns. Understanding these interactions allows for a more comprehensive approach to controlling plant growth in agricultural settings.