Problem 149 - Objective Biology for NEET

Question

The naturally available cytokinin like substance is (a) Kinetin (b) Zeatin (c) Both (a) and (b) (d) None of these

Step-by-Step Solution

Answer

(c) Both (a) and (b)

Step 1 Identify the Cytokinins

Cytokinins are a group of plant hormones that are involved in cell division and plant growth. Kinetin and Zeatin both belong to this class of hormones.

Step 2 Determine if the Cytokinins are Naturally Available

Both Kinetin and Zeatin are naturally available cytokinins. Kinetin was the first cytokinin discovered and isolated. It is found in materials such as yeast extract. Zeatin was discovered in corn (Zea mays) kernels and also has been found in many types of plants in varying quantities.

Step 3 Match the Answer

From steps 1 and 2, it's known that both Kinetin and Zeatin are cytokinins and they are naturally available. Therefore, the answer is (c) Both (a) and (b).

Key Concepts

Plant Hormones

The fascinating world of plant hormones is one that involves intricate processes influencing how plants grow and respond to their environment. Cytokinins, for instance, are one such group of hormones with remarkable functions. They play an essential role in regulating cell division, shoot and root growth, and even delay the aging of plant tissues.

Think of plant hormones as chemical messengers that facilitate communication between different parts of the plant, thereby triggering various developmental processes. Apart from cytokinins, other well-known plant hormones include auxins, gibberellins, abscisic acid, and ethylene. Each hormone serves a specialized function that can either work alone or interact with others to produce a combined effect, ensuring the plant thrives.

Cell Division

Cell division is the engine behind plant growth and reproduction. It's a highly regulated process where a single cell divides into two identical daughter cells. Cytokinins, when paired with another hormone called auxin, encourage the cell division process in plant roots and shoots.

This harmonious interaction directs where and when a plant will grow, meaning cytokinins are crucial for determining plant form and structure. It's important to note that cell division is not haphazard; it's a precise and controlled affair. Plant hormones like cytokinins ensure that cells divide in the right place at the right time, leading to healthy plant development.

Plant Growth

Plant growth is not only about the increase in size but also about the development of the plant through various stages of its life cycle. Cytokinins directly influence this growth by promoting cell division, which translates to an increase in plant mass. They also stimulate shoot formation and leaf expansion, contributing to the green lushness we often admire in plants.

Moreover, cytokinins work together with other hormones to break dormancy in seeds and buds, initiate root formation, and even affect the opening of stomata which are tiny openings on leaves for gas exchange. In a nutrient-rich environment, adequate presence of cytokinins can enhance the plant's nutrient uptake by expanding the root system, thus optimizing the overall health and growth of the plant.