Chemical Coordination in Plants - Biology Chapter 6, Class 10 ICSE

Plants do not possess a nervous system like animals, but they still respond to their environment and coordinate their growth using chemical messengers known as phytohormones. These plant hormones are typically produced in actively growing regions, such as the tips of shoots and roots, and are then transported to other parts of the plant. They help the plant react to changes in light, gravity, and water by either stimulating or inhibiting growth in specific areas. There are five major types of plant hormones, each with distinct functions. Auxins and gibberellins are powerful growth stimulants that promote cell elongation and help stems grow taller. Cytokinins are responsible for stimulating cell division and delaying the aging of plant parts. Ethylene is a unique gaseous hormone widely known for causing fruits to ripen, while abscisic acid acts as a stress hormone that slows down metabolism, inhibits growth, and helps seeds survive harsh conditions. In addition to internal growth regulation, plants exhibit slow, directional growth movements called tropisms in response to external stimuli. For instance, plant shoots naturally grow towards a light source, which is called phototropism, while roots grow downward into the soil due to geotropism. Other important movements include roots growing towards moisture, climbing plants coiling around a support when touched, and pollen tubes growing towards chemicals during reproduction. #dohrao #dohraoicseclass10 #icseclass10 #icseclass10biology