ncert class 10 SCIENCE ch 7CONTROL AND COORDINATION NOTES
Answers
Answer: Control and Coordination
Systematic working of the various organs of an organism (plants or animals) producing a proper response to the stimulus is called co-ordination.
Coordination in Plants
Not so elaborate, controlled by phytohormones and external stimulus.
Phytohormones
• Control and coordination in plants is done by phytohormones.
• They are naturally occurring chemical substances which control one or other aspect of growth.
• Auxin – Cell enlargement and differentiation.
• Gibberellins – In presence of auxin, promotes cell enlargement and differentiation.
• Cytokinins – Promotes cell division, opening of stomata, etc.
• Abscisic acid – Closing of stomata, wilting and falling of leaves, etc.
Tropic Movements
• Directional plant growth movement in response to an external stimulus.
• Growth of a plant may be towards the stimulus (positive tropism) or away from it (negative tropism).
• Phototropism – movement in response to light.
• Chemotropism – in response to chemicals.
• Hydrotropism – in response to water.
• Geotropism – in response to gravity.
Nastic Movements
• Non-directional movement of a plant part in response to an external stimulus.
• May or may not be a growth movement.
• All parts of the organ of a plant are affected equally irrespective of the direction of the stimulus.
• Thigmonasty – Nastic movement in response to touch of an object.
• Photonasty – Nastic movement in response to light.
Coordination in Animals
Elaborate, very complex and is controlled by neuroendocrine system.
Endocrine (chemical) Coordination
• Consists of hormones (chemical messengers) regulating biological processes and secreted by endocrine glands.
• Homeostasis is maintained by hormones by their integrated action and feed back control.
Nervous Coordination
• Neuron forms the fundamental unit.
• Sensory neurons in sense organs receive stimulus and transmit impulses to CNS.
• Motor neurons transmit impulses from CNS to effectors.
• Relay or connector neurons serve as links between sensory and motor neurons.
Nervous System (Human)
• CNS – Consists of brain and spinal cord.
Brain – Controls various voluntary (walking, riding, running, etc.) and involuntary actions (sneezing, coughing, etc). Also controls thinking, reasoning, and intelligence.
Spinal Cord – Controls reflex action.
• PNS – Consists of cranial nerves (12 pairs) and spinal nerves (31 pairs).
• ANS – Two set of nerves (parasympathetic and sympathetic) supplying visceral organs which are antagonistic to each other.
Hope it helps!!
Please mark it as the brainliest..
Have a good day ahead!! :)