Control and Coordination — MCQ Practice
Control and Coordination — Lesson
1) Hook — The Amazing Reflex of a Cricket Player
Imagine a cricket player standing at the crease. A fast bowler delivers the ball at 140 km/h. The player’s eyes see the ball, the brain processes the information, and the muscles of the bat move instantly to hit the ball. All this happens in a fraction of a second! How does the body coordinate such quick actions? This is the magic of Control and Coordination in living organisms.
2) Core Concepts — Understanding Control and Coordination
Control and Coordination is the ability of an organism to regulate its internal activities and respond to external stimuli in a coordinated manner. It involves two main systems in humans:
| System | Function | Example |
|---|---|---|
| Nervous System | Controls rapid, short-term responses using electrical signals | Reflex action when touching a hot object |
| Endocrine System | Controls slow, long-term responses using hormones | Growth and development regulated by hormones like thyroxine |
Nervous System Components
The nervous system consists of:
- Receptors: Detect stimuli (e.g., skin senses heat)
- Brain and Spinal Cord: Process information
- Effectors: Muscles or glands that respond (e.g., muscles move hand away)
Reflex Action (Quick Response)
Reflex action is an automatic and rapid response to a stimulus without conscious thought. It protects the body from harm.
| Step | Description |
|---|---|
| Stimulus | Touching a hot object |
| Receptor | Sensory nerves in skin detect heat |
| Sensory Neuron | Carries impulse to spinal cord |
| Interneuron | Processes information in spinal cord |
| Motor Neuron | Sends impulse to muscle |
| Effector | Muscle contracts and withdraws hand |
Coordination in Plants
Plants also show control and coordination but without a nervous system. They use chemicals called hormones to respond to stimuli.
- Auxins: Promote stem growth towards light (phototropism)
- Gibberellins: Help in seed germination
- Ethylene: Controls fruit ripening (like mangoes)
3) Key Formulas/Rules
Rule 1: Reflex action is a rapid, involuntary response to a stimulus.
Rule 2: Nervous system uses electrical impulses; endocrine system uses chemical messengers (hormones).
Rule 3: In plants, hormones regulate growth and responses to environment.
4) Did You Know?
The human brain has about 100 billion neurons working together to control your body! And the fastest reflex action recorded is the knee-jerk reflex, which happens in just 0.03 seconds.
5) Exam Tips — Score High in Control and Coordination
- Always label diagrams
- Remember key terms: receptor, sensory neuron, interneuron, motor neuron, effector.
- Don’t confuse: Nervous system (fast, electrical) vs Endocrine system (slow, chemical).
- Practice diagram-based questions: Reflex arc is a common question in board exams.
- Use mnemonics: “R SIME” to remember Reflex arc sequence — Receptor → Sensory neuron → Interneuron → Motor neuron → Effector.
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