EXPLAIN ME THE ANWERS OF 12TH NCERT BIOLOGY TABLE 5.3 ?

Table 5.3 in the 12th NCERT Biology textbook provides a concise overview of various types of plant hormones, their functions, and effects on plant growth and development. Understanding these hormones is crucial for grasping how plants respond to their environment and regulate their internal processes. Let’s break down the key components of this table to clarify the information it presents.

Types of Plant Hormones

Plant hormones, also known as phytohormones, are chemical substances that play a vital role in regulating plant growth and development. The main types of hormones included in Table 5.3 are:

• Auxins
• Gibberellins
• Cytokinins
• Abscisic Acid (ABA)
• Ethylene

Auxins

Auxins are primarily involved in cell elongation, root formation, and the regulation of fruit development. They are produced in the tips of shoots and roots and promote growth by loosening the cell walls, allowing cells to expand. A common example is the way auxins help plants grow towards light, a phenomenon known as phototropism.

Gibberellins

Gibberellins are crucial for seed germination, stem elongation, and flowering. They stimulate the production of enzymes that break down food reserves in seeds, providing energy for growth. For instance, when a seed absorbs water, gibberellins are activated, leading to the sprouting of the seed.

Cytokinins

Cytokinins promote cell division and are involved in the growth of lateral buds and the delay of leaf senescence (aging). They are often found in areas of active growth, such as roots and developing fruits. An example of their effect is seen when they are applied to cuttings, which can enhance root development.

Abscisic Acid (ABA)

ABA plays a critical role in stress responses, particularly in drought conditions. It helps to close stomata to reduce water loss and can inhibit growth during unfavorable conditions. This hormone acts as a signal for the plant to conserve resources, ensuring survival during tough times.

Ethylene

Ethylene is unique among plant hormones as it is a gas. It regulates fruit ripening, flower wilting, and leaf fall. For example, when fruits ripen, they release ethylene, which accelerates the ripening process in nearby fruits, a phenomenon often utilized in agriculture to synchronize ripening.

Interplay of Hormones

These hormones do not act in isolation; they often interact with each other to regulate various physiological processes. For instance, auxins and cytokinins work together to promote cell division and differentiation, while gibberellins and ethylene can influence fruit development and ripening.

Practical Applications

Understanding these hormones has practical implications in agriculture and horticulture. For example, farmers can use synthetic auxins to promote root growth in cuttings or gibberellins to enhance fruit size and yield. Ethylene is used in controlled ripening processes to ensure that fruits reach the market at the right time.

In summary, Table 5.3 in the NCERT Biology textbook encapsulates the essential roles of various plant hormones, highlighting their significance in plant growth and development. By understanding these hormones, we can appreciate how plants adapt to their environment and how we can manipulate these processes for agricultural benefits.