Chapter 3: Control and Coordination Notes – Class 10 Science (MSBSHSE)

Welcome to Chapter 3: Control and Coordination — a fascinating topic where we discover how living organisms sense changes and respond accurately. This chapter explores plant and animal systems that coordinate actions, essential for maintaining balance and survival.

🔹 1. What is Control and Coordination?

Definition: The ability of organisms to regulate internal processes and respond to external stimuli through communication systems like nerves and hormones.

Key terms: stimulus, receptors, response, homeostasis, reflex action.

🔹 2. Nervous System in Animals

• Structure: Brain, spinal cord, nerves forming the Central and Peripheral Nervous Systems.
• Function: Receives stimulus via receptors → transmits signal → CNS processes it → sends response via effector organs.

🔹 3. Reflex Action

A rapid, involuntary response to a stimulus without conscious thought.

• Example: Knee jerk reflex—striking patellar tendon causes leg to kick.
• Pathway: Stimulus → receptor → sensory neuron → spinal cord → motor neuron → effector → response.

Reflex arc – stimulus, transmission, response.

🔹 4. Hormonal Coordination in Animals

Endocrine glands secrete hormones carried by bloodstream to effectors, controlling long-term processes:

• Pituitary gland: Growth hormone secretion
• Thyroid gland: Regulates metabolism
• Adrenal gland: Produces adrenaline during emergencies
• Pineal gland: Controls sleep-wake cycle via melatonin

🔹 5. Control in Plants

Though plants lack a nervous system, they respond to stimuli through growth movements called tropisms:

• Phototropism: Growth toward light (shoots)
• Geotropism: Roots grow downward, shoots upward
• Hydrotropism: Roots grow toward water
• Thigmotropism: Climbing plants wrap around support

These movements are regulated by plant hormones such as auxin and gibberellin.

🔹 6. Plant Hormones

• Auxin: Promotes cell elongation, root growth
• Gibberellins: Promote stem elongation
• Cytokinins: Promote cell division
• Ethylene: Promotes fruit ripening
• Abscisic acid: Causes stomatal closure and seed dormancy

🔹 7. Comparison: Nervous vs Endocrine Systems

🔹 8. Solved Examples & Definitions

1. Define reflex arc: Pathway of fastest response through spinal cord.
2. Phototropism situation: How shoots bend toward light due to auxin accumulation.
3. Difference question: Nervous vs endocrine systems – list 2–3 differences.

🔹 9. Exam Tips (Last 5 Years)

• Give diagram of neuron and label its parts.
• Explain reflex action with diagram and sequence.
• List plant movements and identify their tropism type.
• Compare two control systems with three difference points.
• Name 2–3 plant hormones and their functions.

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• Chapter 1: Gravitation
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