Question

Describe co-ordination in plants with examples.

Hint:

In plants, coordination occurs through hormones. For example, auxins control growth towards light, gibberellins aid in seed germination, and ethylene regulates ripening of fruits.

Answer 1

Coordination in plants refers to the ability of plants to respond to environmental stimuli and regulate their growth and activities in order to survive. Unlike animals, plants do not have a nervous system, but they use chemical messengers and hormones for coordination. The primary mechanism of plant coordination is the action of plant hormones or phytohormones. The major types of plant hormones involved in coordination are: 1. Auxins: Auxins are responsible for cell elongation and are mainly involved in the growth of the plant towards light (phototropism) or gravity (gravitropism). An example is the way auxins accumulate on the shaded side of a plant shoot, causing it to bend towards the light. 2. Gibberellins: Gibberellins promote growth and development, especially in the elongation of stems and germination of seeds. An example is the way gibberellins help in seed germination by breaking dormancy. 3. Cytokinins: Cytokinins are involved in cell division and differentiation. They are found in areas of rapid growth, such as in the roots and fruits, and promote the growth of lateral buds and delay aging. 4. Ethylene: Ethylene is a gaseous plant hormone that regulates fruit ripening. It also influences leaf abscission and senescence. For example, the ripening of bananas is stimulated by ethylene. 5. Abscisic Acid (ABA): ABA plays a key role in stress responses and in regulating stomatal closure during water scarcity. It helps in the plant's response to drought. Example of Coordination in Plants:
An example of plant coordination is the bending of a plant stem towards light, known as phototropism. The cells on the darker side of the plant shoot elongate due to the action of auxins, causing the plant to bend towards the light source. This process helps the plant to maximize its exposure to sunlight for photosynthesis.