Problem 131 - Objective Biology for NEET

Question

Different types of gibberellins is reported from what kind of organisms? (a) Fungi (b) Higher plants (c) Both (a) and (b) (d) None of these

Step-by-Step Solution

Answer

The correct answer is (c), both Fungi and Higher plants.

Step 1: Identifying the Role and Origin of Gibberellins

Gibberellins are a group of plant hormones that regulate growth and influence various developmental processes. They were first discovered in the fungus Gibberella fujikuroi, from which they get their name. Apart from fungi, gibberellins are also known to occur in higher plants.

Step 2: Matching the Information with Choices

Looking at the multiple choices, it can be seen that Gibberellins occur in both Fungi (option a) and Higher plants (option b). Therefore, both options are correct.

Step 3: Determining the Correct Answer

Since both Fungi and Higher plants are correct answers, the option that includes both should be chosen. In this case, it's option c, both (a) and (b).

Key Concepts

Plant Hormones

Plant hormones, also called phytohormones, are naturally occurring organic substances that regulate different facets of plant growth and development. They have profound effects even at low concentrations and are active in various processes like germination, root growth, stem elongation, flowering, and fruit ripening.

One of the key groups of plant hormones is the gibberellins. These are crucial for stimulating growth, particularly by elongating cells and causing seed germination. Gibberellins are also involved in overcoming dormancy in seeds and buds, sex expression, and enzyme activation necessary for providing nutrients during seed germination.

To help with understanding, consider that these hormones act like signals, telling the plant when to grow taller, when to start flowering, and when to push a seed to sprout. They're like natural 'text messages' instructing various parts of the plants to perform certain actions at just the right time.

Growth Regulation

Growth regulation in plants is a sophisticated process controlled by the interplay of several plant hormones, of which gibberellins play a pivotal role. Because they promote cell elongation, they are particularly important in stem growth. Think of gibberellins as the 'green light' that tells cells to extend, leading to taller plants.

Applications in Agriculture

Understanding gibberellins has practical applications in agriculture; for instance, they are used to increase the size of fruits and the amount of space inside them by promoting cell division and elongation. Moreover, they can break the dormancy of seeds, which benefits farmers by ensuring more uniform germination and, consequently, crop yield.

However, it's essential to realize that balance is crucial. Too much gibberellin activity can lead to excessive growth, causing plants to become weak and spindly. Meanwhile, too little activity can make them stunted. Thus, growth regulation via hormone balance is key to healthy plant development.

Gibberella Fujikuroi

The discovery of gibberellins has its roots in a disease in rice known as 'bakanae', or 'foolish seedling', which caused the seedlings to grow excessively tall and then die. This disease was eventually traced back to a fungal infection by Gibberella fujikuroi.

Researchers learned that this fungus produced a substance that caused the abnormal growth in the rice plants - now known as gibberellins. This finding extended to uncovering similar hormones in higher plants, revealing the ubiquitous role of gibberellins in the plant kingdom.

So, Gibberella fujikuroi is not just a footnote in the history of plant science; it represents the fascinating intersection of plant pathology and hormonal research, where a significant plant hormone was first identified thanks to a disease-causing organism. The understanding of its mechanism has had considerable implications for both basic botanical research and the practical management of crop growth.