🧠 Chapter 2 – Control and Coordination (Biology)

📘 Subject: Biology

🧑‍🏫 Class: 10 CBSE
🧪 Book: Science (NCERT)

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🤔 What is Control and Coordination?

It refers to the ability of an organism to respond to stimuli and regulate body functions using:

• Nervous system

• Endocrine system (hormones)

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🧠 Control and Coordination in Animals

1. Nervous System

👉 Made of:

• Brain

• Spinal cord

• Nerves

➤ Neurons

• Functional unit of the nervous system

• Transmit electrical impulses

🔹 Parts:

Part	Function
Dendrites	Receive signals
Axon	Transmit signals
Axon terminals	Pass signal to next neuron

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2. Human Nervous System

Divided into:

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

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

🧠 Human Brain

Part	Function
Cerebrum	Thinking, memory, senses, voluntary actions
Cerebellum	Balance and posture
Medulla (Brainstem)	Involuntary actions like heartbeat, breathing

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⚡ Reflex Action

• Quick, automatic response to a stimulus

• Example: removing hand from hot surface

• Reflex Arc: Path taken by nerve impulse in reflex (Receptor → Sensory Neuron → Spinal Cord → Motor Neuron → Effector)

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🌱 Coordination in Plants

Plants don’t have a brain or nerves but show movement in response to stimuli.

Types of Movements:

Type	Based on Direction	Example
Tropism	Directional	Roots grow towards gravity
Nastic	Non-directional	Touch-me-not plant closes

➤ Tropic Movements:

Tropism	Stimulus	Example
Phototropism	Light	Shoot bends toward light
Geotropism	Gravity	Root grows downward
Hydrotropism	Water	Roots toward water
Thigmotropism	Touch	Tendrils of climbers
Chemotropism	Chemicals	Pollen tube growth

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💉 Hormones in Animals (Endocrine System)

Hormones: Chemical messengers secreted by glands to regulate body functions.

Gland	Hormone	Function
Pituitary	Growth hormone	Controls growth
Thyroid	Thyroxine	Regulates metabolism
Adrenal	Adrenaline	Fight or flight response
Pancreas	Insulin	Controls blood sugar levels
Testes/Ovaries	Testosterone/Estrogen	Sex characteristics

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📌 Important Diagrams to Practice

✅ Neuron structure
✅ Human brain with parts
✅ Reflex arc
✅ Tropic movements in plants

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📝 Extra Questions & Answers

Q1: What is the role of brain in reflex action?
👉 Brain is not involved in reflex actions; it is handled by the spinal cord for quick response.

Q2: Why do tendrils coil around a support?
👉 Due to thigmotropism – response to touch.

Q3: How do auxins affect plant growth?
👉 Auxins are plant hormones that promote growth toward light (phototropism).

Q4: What is the difference between nervous and hormonal control?

Nervous System	Hormonal System
Fast and immediate	Slow and long-lasting
Uses electrical impulses	Uses chemical messengers

Q5: Name two involuntary actions controlled by the brain.
👉 Breathing and heartbeat (controlled by medulla).

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✨ Summary Points

• Neurons: carry signals in body

• Reflex arc: quick reaction system

• Brain: controls voluntary & involuntary actions

• Plant movements: based on light, gravity, touch

• Hormones: regulate body processes (growth, sugar, stress)