CBSE Class 10 - Control and Coordination Notes & MCQ

January 06, 2026

Control and Coordination

Control and Coordination

1. Introduction – What is Control & Coordination?

All living organisms respond to stimuli (changes in surroundings)

  • Control → Regulation of body functions
  • Coordination → Working together of different organs/systems
  • In animals → Mainly by Nervous system + Endocrine system (hormones)
  • In plants → Mainly by plant hormones (no nervous system)

2. Coordination in Animals – Nervous System

Basic unit → Neuron (Nerve cell)

Structure of a Neuron (Very important diagram)

Main parts:

  • Cell body (cyton) → Contains nucleus & cytoplasm
  • Dendrites → Short branched fibres → Receive impulses
  • Axon → Long fibre → Conducts impulse away from cell body
  • Nerve ending → At the end of axon → Makes connection with next neuron/muscle

Synapse → Gap/junction between two neurons (or neuron & muscle)
→ Impulse jumps via chemicals called neurotransmitters

Types of Neurons:

  • Sensory (afferent) → Carry impulse from receptor → CNS
  • Motor (efferent) → Carry impulse from CNS → Effector
  • Interneuron → Connect sensory & motor neurons

3. Reflex Action & Reflex Arc (Most Important for Exams)

Reflex action → Sudden, automatic, involuntary response to a stimulus (very fast)

Example → Withdrawal of hand on touching hot object, knee-jerk, blinking when something approaches eye

Reflex Arc → Pathway of reflex action (shortest route)

Components (Important diagram):

  • Receptor → Skin/tongue/eye (detects stimulus)
  • Sensory neuron → Carries impulse to spinal cord
  • Spinal cord → Processes & sends response (most reflexes are spinal)
  • Motor neuron → Carries impulse to effector
  • Effector → Muscle/gland (gives response)

Example: Hot object → Pain receptor in skin → Sensory neuron → Spinal cord → Motor neuron → Arm muscle contracts → Hand pulled back

Advantage → Protects body from damage (very fast, no need to think)

4. Human Nervous System

Divided into two parts:

A. Central Nervous System (CNS)
Brain + Spinal cord

B. Peripheral Nervous System (PNS)
Cranial nerves (12 pairs) + Spinal nerves (31 pairs)

Human Brain (Very important diagram & functions)

Protected by cranium (skull) & cerebrospinal fluid (shock absorber)

Part Location Main Functions
Cerebrum Largest part (2 hemispheres) Thinking, memory, reasoning, voluntary actions, intelligence, speech
Cerebellum Hindbrain Maintains body balance, posture & coordination of voluntary movements
Medulla Oblongata Connects brain & spinal cord Controls involuntary actions (breathing, heartbeat, swallowing, vomiting, blood pressure)
Midbrain Small region Controls reflex actions of eye & head
Hypothalamus Below thalamus Controls hunger, thirst, sleep, body temperature, pituitary gland

5. Coordination in Plants

Plants do not have nervous system → Coordination by plant hormones (phytohormones) + tropisms

Important Plant Hormones:

Hormone Main Function Example/Effect
Auxin Cell elongation, promotes growth Phototropism (stem bends towards light)
Gibberellin Stem elongation, seed germination Increases stem length (tall plants)
Cytokinin Cell division, delays ageing Promotes cell division in shoot tips
Abscisic Acid (ABA) Stress hormone, closes stomata, inhibits growth Closes stomata during water stress
Ethylene Fruit ripening, promotes ageing Ripens fruits (banana, mango)

Tropisms → Directional movements in response to stimulus

  • Phototropism → Towards light (stem → positive, root → negative)
  • Geotropism → Towards gravity (root → positive, stem → negative)
  • Hydrotropism → Towards water (root)
  • Thigmotropism → Touch (tendrils of pea, touch-me-not plant)

Nastic movements → Non-directional (e.g., touch-me-not folds leaves on touch)

6. Coordination by Hormones – Endocrine System

Endocrine glands → Ductless glands → Secrete hormones directly into blood

Important Human Endocrine Glands:

Gland Hormone(s) Main Functions
Pituitary (Master gland) Growth hormone, TSH, ACTH etc. Controls other glands, growth, metabolism
Thyroid Thyroxine Regulates metabolism, growth & development
Parathyroid Parathormone Regulates calcium & phosphorus
Adrenal Adrenaline, Cortisol Emergency hormone → increases heart rate, breathing
Pancreas Insulin & Glucagon Regulates blood sugar (Insulin → ↓ sugar, Glucagon → ↑ sugar)
Gonads (Testis/Ovary) Testosterone / Estrogen Secondary sexual characters, reproduction

Feedback mechanism → Helps maintain hormone level (e.g., high sugar → insulin release → sugar decreases → insulin decreases)

Quick Revision Table – Most Important Points for Exams

  • Neuron = Functional unit of nervous system
  • Reflex arc = Shortest path for reflex action
  • Cerebrum → Thinking & voluntary actions
  • Cerebellum → Balance & coordination
  • Medulla → Involuntary actions (breathing, heartbeat)
  • Auxin → Phototropism
  • Adrenaline → Fight or flight hormone
  • Insulin → Decreases blood sugar
  • Pituitary → Master gland

MCQs: Control and Coordination

1. Which of the following is the functional unit of the nervous system?
  • a) Nephron
  • b) Neuron
  • c) Alveoli
  • d) Osteon
Answer: b) Neuron
(Neuron is the basic structural and functional unit of the nervous system.)
2. The gap between two neurons through which chemical signals are transmitted is called:
  • a) Axon
  • b) Dendrite
  • c) Synapse
  • d) Axon terminal
Answer: c) Synapse
(Synapse is the junction where neurotransmitters are released.)
3. A sudden automatic involuntary response to a stimulus is called:
  • a) Voluntary action
  • b) Reflex action
  • c) Hormonal response
  • d) Tropism
Answer: b) Reflex action
(Reflex actions are fast, involuntary protective responses.)
4. In the human reflex arc, the correct sequence of components is:
  • a) Receptor → Motor neuron → Sensory neuron → Effector
  • b) Receptor → Sensory neuron → Spinal cord → Motor neuron → Effector
  • c) Effector → Sensory neuron → Spinal cord → Receptor
  • d) Motor neuron → Receptor → Sensory neuron
Answer: b) Receptor → Sensory neuron → Spinal cord → Motor neuron → Effector
(This is the standard pathway for a spinal reflex.)
5. Which part of the brain maintains body balance and posture?
  • a) Cerebrum
  • b) Cerebellum
  • c) Medulla oblongata
  • d) Hypothalamus
Answer: b) Cerebellum
(Cerebellum coordinates voluntary movements and balance.)
6. The main thinking part of the human brain is:
  • a) Cerebellum
  • b) Midbrain
  • c) Cerebrum
  • d) Medulla
Answer: c) Cerebrum
(Cerebrum controls intelligence, memory, reasoning and voluntary actions.)
7. Which hormone is known as the "fight or flight" hormone?
  • a) Insulin
  • b) Thyroxine
  • c) Adrenaline
  • d) Growth hormone
Answer: c) Adrenaline
(Adrenaline prepares the body for emergency situations by increasing heart rate and breathing.)
8. The hormone that regulates blood sugar level is:
  • a) Thyroxine
  • b) Insulin
  • c) Estrogen
  • d) Adrenaline
Answer: b) Insulin
(Insulin lowers blood glucose level; deficiency causes diabetes.)
9. Which plant hormone promotes cell elongation and is responsible for phototropism?
  • a) Gibberellin
  • b) Cytokinin
  • c) Auxin
  • d) Abscisic acid
Answer: c) Auxin
(Auxin causes bending of stem towards light - positive phototropism.)
10. The movement of plant roots towards water is called:
  • a) Phototropism
  • b) Geotropism
  • c) Hydrotropism
  • d) Thigmotropism
Answer: c) Hydrotropism
(Hydrotropism is the response of roots towards water.)
11. The growth of tendrils in pea plants towards support is an example of:
  • a) Phototropism
  • b) Geotropism
  • c) Thigmotropism
  • d) Chemotropism
Answer: c) Thigmotropism
(Thigmotropism is the response to touch.)
12. Which plant hormone is responsible for fruit ripening?
  • a) Auxin
  • b) Ethylene
  • c) Cytokinin
  • d) Gibberellin
Answer: b) Ethylene
(Ethylene promotes ripening in fruits like banana and mango.)
13. The master gland that controls other endocrine glands is:
  • a) Thyroid
  • b) Adrenal
  • c) Pituitary
  • d) Pancreas
Answer: c) Pituitary
(Pituitary is called the master gland as it regulates most other glands.)
14. The hormone that helps plants withstand stress by closing stomata is:
  • a) Auxin
  • b) Gibberellin
  • c) Abscisic acid
  • d) Ethylene
Answer: c) Abscisic acid
(ABA is a stress hormone.)
15. Electrical impulses travel in a neuron from:
  • a) Axon → Dendrite → Cell body
  • b) Dendrite → Cell body → Axon
  • c) Cell body → Axon → Dendrite
  • d) Axon → Cell body → Dendrite
Answer: b) Dendrite → Cell body → Axon
(This is the direction of impulse conduction.)
16. Which of the following controls involuntary actions like breathing and heartbeat?
  • a) Cerebrum
  • b) Cerebellum
  • c) Medulla oblongata
  • d) Hypothalamus
Answer: c) Medulla oblongata
(Medulla controls vital involuntary functions.)
17. The movement of shoot away from gravity is an example of:
  • a) Positive geotropism
  • b) Negative geotropism
  • c) Positive phototropism
  • d) Negative hydrotropism
Answer: b) Negative geotropism
(Stem shows negative geotropism.)
18. Which gland secretes thyroxine hormone?
  • a) Pancreas
  • b) Thyroid
  • c) Adrenal
  • d) Pituitary
Answer: b) Thyroid
(Thyroxine regulates metabolism.)
19. The non-directional movement shown by touch-me-not plant is:
  • a) Tropic movement
  • b) Nastic movement
  • c) Phototropic movement
  • d) Geotropic movement
Answer: b) Nastic movement
(Nastic movements are non-directional.)
20. Which of these is NOT a function of the cerebrum?
  • a) Thinking & reasoning
  • b) Memory
  • c) Maintaining body balance
  • d) Voluntary actions
Answer: c) Maintaining body balance
(Balance is controlled by cerebellum, not cerebrum.)

Post a Comment

0 Comments