Chapter 6 — Control and Coordination

NCERT Class 10 Science Chapter 6 covers Control and Coordination — the mechanisms by which the nervous system and hormones enable animals and plants to detect environmental stimuli and respond appropriately through electrical impulses, reflex arcs, brain regions, and chemical signals.

Chapter 6 explains how living organisms achieve control and coordination through two main systems. In animals, the nervous system uses specialised nerve cells (neurons) to transmit electrical impulses across synapses, enabling reflex actions (processed in the spinal cord) and voluntary actions (processed in the brain). The human brain comprises the fore-brain (thinking, sensory interpretation), mid-brain and hind-brain (involuntary actions, balance via cerebellum). Plants lack nerves but respond via directional growth movements called tropisms (phototropism, geotropism) driven by hormones such as auxin, gibberellins, cytokinins and abscisic acid. Animals use hormones like adrenaline, insulin, thyroxin and growth hormone for chemical coordination, regulated through feedback mechanisms.

1. 01Neurons carry information as electrical impulses from dendrites through the cell body and axon; chemicals released at synapses bridge the gap to the next neuron or effector cell.
2. 02Reflex arcs are rapid, involuntary pathways processed in the spinal cord (not the brain), allowing quick responses such as withdrawing a hand from a flame.
3. 03The human brain has three regions: fore-brain (thinking, sensory areas), mid-brain/hind-brain (involuntary actions, blood pressure, salivation), and cerebellum (posture and balance).
4. 04Plants show two types of movement: growth-independent (e.g., sensitive plant folding leaves via water pressure changes) and growth-dependent tropisms (phototropism, geotropism, hydrotropism, chemotropism).
5. 05Auxin synthesised at the shoot tip causes unequal cell elongation, bending the plant towards light; gibberellins and cytokinins promote growth while abscisic acid inhibits it and causes leaf wilting.
6. 06Animal hormones including adrenaline (fight-or-flight), insulin (blood sugar regulation), thyroxin (metabolism), and growth hormone (development) are secreted by endocrine glands and regulated by feedback mechanisms.