Class 10 Science Chapter 7: Control and Coordination – Notes & Summary

🔰 Introduction

Living organisms respond to various stimuli like light, sound, touch, and chemicals. These responses are controlled and coordinated by their nervous and hormonal systems.

In animals, control and coordination is carried out by:

• Nervous system

• Endocrine (hormonal) system

In plants, control and coordination occurs through:

• Hormones (Phytohormones)

• Tropisms

🧠 1. Control and Coordination in Animals

🔹 Nervous System

• Composed of brain, spinal cord, and nerves.

• The basic unit of the nervous system is the neuron.

🔹 Parts of Nervous System

• Central Nervous System (CNS): Brain + Spinal Cord

• Peripheral Nervous System (PNS): Nerves from CNS to body

• Autonomic Nervous System: Involuntary actions

🔹 Human Brain

• Cerebrum: Intelligence, memory, voluntary actions

• Cerebellum: Balance and coordination

• Medulla: Controls involuntary actions like heartbeat, breathing

🔹 Reflex Action

• Quick automatic response to a stimulus

• Example: Pulling hand away from hot object

• Involves sensory nerve, spinal cord, and motor nerve

💉 2. Hormonal Control in Animals

Hormones: Chemical messengers secreted by endocrine glands directly into the bloodstream.

Important Human Hormones:

🌱 3. Control and Coordination in Plants

Plants do not have a nervous system but still show controlled responses.

🔹 Tropic Movements:

• Tropism: Growth movement toward or away from a stimulus.

• Types:

  • Phototropism: Response to light (shoots grow toward light)

  • Geotropism: Response to gravity (roots grow downward)

  • Hydrotropism: Response to water

  • Thigmotropism: Response to touch (e.g., tendrils)

🔹 Nastic Movements:

• Non-directional response (e.g., touch-me-not plant folds leaves)

🔹 Plant Hormones (Phytohormones):

• Auxins: Cell growth

• Gibberellins: Stem elongation

• Cytokinins: Cell division

• Abscisic Acid: Inhibits growth, causes wilting

✅ Key Points to Remember

• Neuron is the structural and functional unit of the nervous system.

• Reflex actions are quick responses controlled by the spinal cord.

• Hormones help in coordination by chemical control.

• Plants respond to stimuli using hormones and tropic movements.