Control and Coordination NCERT Class 10

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 🔬 Chapter 7: Control and Coordination

Class 10 Science – Biology

(by https://www.thecreativesciences.com/p/contact-us.html ) 

🌟 Overview

All living organisms respond to internal and external stimuli. For this, they require coordination systems.

  • In animals, coordination is carried out by the nervous system and endocrine system.
  • In plants, coordination happens through plant hormones and tropic/nastic movements.

 

🧠 I. Control and Coordination in Animals

 

🔹 1. The Nervous System

🔸 Function:

  • Detects stimuli
  • Processes information
  • Coordinates a response (e.g., muscle action, gland secretion)

🔸 Neuron – Structure and Function

  • Functional unit of the nervous system
  • Transmits electrical impulses

Parts of a Neuron:

Part

Function

Dendrites

Receive signals from receptors or other neurons

Cell body

Contains nucleus, processes the signal

Axon

Conducts impulse away from the cell body

Axon terminals

Transmit signal to next neuron or muscle via synapse

🔸 Synapse

  • A small gap between two neurons
  • Transfers impulse via neurotransmitters
  • Converts electrical signal → chemical → electrical again in next neuron

 

🔹 2. Reflex Action

🔸 Definition:

  • Immediate, automatic, involuntary response to a stimulus (e.g., withdrawing hand from flame)

🔸 Components:

  • Stimulus → Receptor → Sensory neuron → Spinal cord (Relay neuron) → Motor neuron → Effector (muscle)

🔸 Reflex Arc:

  • The neural pathway followed in a reflex action
  • Allows fast response without delay of thinking

 

🔹 3. Human Nervous System

a. Central Nervous System (CNS)

  • Brain and spinal cord
  • Processes and interprets information

b. Peripheral Nervous System (PNS)

  • Nerves that connect CNS to rest of the body
  • Includes cranial and spinal nerves

c. Autonomic Nervous System (ANS)

  • Involuntary actions (e.g., heartbeat, digestion)
  • Two divisions:
    • Sympathetic – "Fight or flight" (increases activity)
    • Parasympathetic – "Rest and digest" (slows down activity)

 

🔹 4. Human Brain

Protected by:

  • Skull
  • Meninges (three-layered membrane)
  • Cerebrospinal fluid (shock absorber)

Parts of the Brain:

Part

Function

Cerebrum

Largest part; intelligence, memory, voluntary actions, thinking

Cerebellum

Coordination of body movement and balance

Medulla oblongata

Controls involuntary functions (heartbeat, respiration)

Pons

Helps medulla in regulating breathing

Midbrain

Controls reflex movements of head and eyes

🧬 II. Coordination through Hormones (Endocrine System)

 

🔹 Hormones

  • Chemical messengers secreted by endocrine glands
  • Transported through blood
  • Act on target organs
  • Help regulate long-term changes (growth, development, metabolism)

🔸 Important Human Endocrine Glands:

Gland

Hormone

Function

Pituitary (master gland)

Growth hormone, others

Controls growth, regulates other glands

Thyroid

Thyroxine

Regulates metabolism, needs iodine

Pancreas

Insulin, Glucagon

Regulates blood sugar levels

Adrenal

Adrenaline

Prepares body for emergency ("fight or flight")

Testes (males)

Testosterone

Male sexual features

Ovaries (females)

Estrogen, Progesterone

Female sexual features, menstrual cycle

🔸 Feedback Mechanism

  • Regulates hormone levels (e.g., low thyroxine → pituitary releases more TSH)

 

🌱 III. Control and Coordination in Plants

 

🔹 1. Plant Movements

a. Tropic Movements (directional)

  • Response to environmental stimuli with growth movement toward/away from stimulus

Type

Stimulus

Example

Phototropism

Light

Shoots grow toward light

Geotropism

Gravity

Roots grow downward

Hydrotropism

Water

Roots grow toward moisture

Thigmotropism

Touch

Tendrils coil around support

Chemotropism

Chemicals

Growth of pollen tube toward ovule

b. Nastic Movements (non-directional)

  • Independent of direction of stimulus
  • Examples:
    • Mimosa pudica folding leaves on touch (thigmonasty)
    • Flower opening or closing due to temperature

 

🔹 2. Plant Hormones (Phytohormones)

Hormone

Function

Auxin

Promotes cell elongation, root initiation, phototropism

Gibberellins

Promotes stem elongation, germination

Cytokinins

Stimulates cell division, delays aging

Abscisic Acid

Inhibits growth, promotes dormancy, causes wilting

Ethylene

Promotes fruit ripening, leaf fall

✅ Key Takeaways

  • Animals use electrochemical systems (nerves) and chemical messengers (hormones) for control and coordination.
  • Reflex actions are fast and bypass brain thinking centers.
  • The brain is the main coordination center with specialized regions.
  • Hormones maintain internal balance, regulate processes like growth and stress.
  • Plants coordinate without a nervous system, using growth-based movements and hormones.

 

INTEXT QUESTION- ANSWERS

SET-1

Q1: What is the difference between a reflex action and walking?

Answer:

  • Reflex action is an involuntary, automatic, and quick response to a stimulus (e.g., pulling hand away from hot object).

  • Walking is a voluntary action that is controlled by our brain and requires thinking and coordination.

Q2: What happens at the synapse between two neurons?

Answer:
At the synapse, the axon terminal of one neuron releases chemical neurotransmitters, which cross the gap and transmit the signal to the dendrite of the next neuron. This converts the electrical impulse → chemical → electrical again.

Q3: Which part of the brain maintains posture and equilibrium of the body?

Answer:
The cerebellum (part of the hindbrain) maintains posture and equilibrium of the body.

Q4: How do we detect the smell of an agarbatti (incense stick)?

Answer:

  • Smell receptors in the nose detect the chemicals from the agarbatti.

  • These receptors send electrical signals to the forebrain.

  • The forebrain interprets these signals as the smell of agarbatti.

Q5: What is the role of the brain in reflex action?

Answer:
The brain does not directly control reflex actions. They are controlled by the spinal cord through a reflex arc. However, the brain is informed of the reflex action afterward.


SET 2

Q1: What are plant hormones?

Answer:
Plant hormones or phytohormones are chemical substances that regulate various physiological processes in plants like growth, flowering, fruiting, and responses to stimuli.

Q2: How is the movement of leaves of the sensitive plant different from the movement of a shoot towards light?

Answer:

Movement in Sensitive Plant (Mimosa)

Movement of Shoot toward Light

Touch-sensitive, quick movement

Growth movement, slow

Nastic movement (non-directional)

Tropic movement (directional)

No growth involved

Growth involved

Temporary movement

Permanent change in position

Q3: Give an example of a plant hormone that promotes growth.

Answer:
Auxin is a plant hormone that promotes growth by cell elongation, especially in shoots.

Q4: How do auxins promote the growth of a tendril around a support?

Answer:
Auxins accumulate on the shaded side of the tendril. This causes faster cell growth on that side, making the tendril curl around the support.

Q5: Design an experiment to demonstrate phototropism.

Answer:
Experiment:

  • Take a potted plant and keep it in a box with a hole on one side (light can enter from one direction).

  • Keep the setup near a light source for a few days.

  • Observation: The plant bends toward the light.

  • Conclusion: This shows positive phototropism in shoots.

SET3

Q1: How does chemical coordination take place in animals?

Answer:
Chemical coordination in animals takes place through hormones secreted by endocrine glands. These hormones are released into the bloodstream and regulate activities like growth, metabolism, reproduction, etc.

Q2: Why is the use of iodised salt advisable?

Answer:
Iodine is essential for the thyroid gland to produce thyroxine. A lack of iodine causes goitre (swelling of the neck). So, iodised salt prevents iodine deficiency.

Q3: How does our body respond when adrenaline is secreted into the blood?

Answer:
Adrenaline increases heart rate, breathing rate, blood pressure, and blood supply to muscles. It prepares the body for a fight-or-flight response during stressful situations.

Q4: Why are some patients of diabetes treated by giving injections of insulin?

Answer:
In diabetes, the pancreas does not produce enough insulin, which is required to control blood sugar levels. Therefore, insulin injections help maintain normal sugar levels.


NCERT Exercise Solutions

🔹 Q1: Which of the following is a plant hormone?

(a) Insulin (b) Thyroxine (c) Oestrogen (d) Cytokinin

Answer:
✅ (d) Cytokinin

(The others are animal hormones.)

🔹 Q2: The gap between two neurons is called a:

(a) dendrite (b) synapse (c) axon (d) impulse

Answer:
✅ (b) synapse

🔹 Q3: The brain is responsible for:

(a) thinking (b) regulating heartbeat (c) balancing the body (d) all of the above

Answer:
✅ (d) all of the above

🔹 Q4: What is the function of receptors in our body?

Think of situations where receptors do not work properly. What problems are likely to arise?

Answer:

  • Receptors detect stimuli (e.g., heat, pain, light, smell) and send signals to the brain/spinal cord.

  • If receptors don’t work properly:

    • The body cannot respond to stimuli.

    • May lead to injuries or danger, e.g., not pulling hand away from fire if pain receptors fail.

🔹 Q5: Draw the structure of a neuron and explain its function.

Answer:

Function of Neuron:

  • Transmits messages as electrical impulses from one part of the body to another.

  • Carries signals from receptors to CNS and from CNS to effectors (muscles/glands).

(You should draw a labeled diagram with: Dendrites, Cell Body, Axon, Axon Terminals, Myelin Sheath.)

🔹 Q6: How does phototropism occur in plants?

Answer:

  • Phototropism is the growth of plant parts in response to light.

  • Auxin hormone collects on the shaded side of the plant.

  • It causes more growth on that side, making the plant bend toward light (positive phototropism).

🔹 Q7: Which signals will get disrupted in case of a spinal cord injury?

Answer:

  • Reflex actions, motor responses, and sensory input will be disrupted.

  • Messages from body to brain and vice versa may not be transmitted, leading to paralysis or loss of sensation.

🔹 Q8: How does chemical coordination occur in animals?

Answer:

  • Through hormones secreted by endocrine glands.

  • Hormones are released into the bloodstream and travel to target organs to regulate growth, metabolism, and other functions.

  • E.g., Insulin controls blood sugar levels.

🔹 Q9: What is the need for a system of control and coordination in an organism?

Answer:

  • To maintain internal balance (homeostasis).

  • To respond to changes in the environment.

  • To coordinate different organs and systems efficiently.

  • Without coordination, body functions would become disorganized.

  • 🔹 Q10: How are involuntary actions and reflex actions different from each other?

    Feature

    Involuntary Action

    Reflex Action

    Controlled by

    Brain

    Spinal cord

    Speed

    Slower

    Very fast

    Conscious thought

    Not under conscious control

    Immediate and automatic

    Example

    Breathing, heartbeat

    Pulling hand from hot object

    🔹 Q11: Compare and contrast nervous and hormonal mechanisms for control and coordination in animals.

    Feature

    Nervous System

    Hormonal System

    Nature of signal

    Electrical impulse

    Chemical (hormones)

    Speed

    Fast

    Slow

    Duration

    Short-term

    Long-term

    Carried by

    Neurons

    Blood

    Voluntary/Involuntary

    Mostly voluntary and reflex actions

    Mostly involuntary

    Example

    Moving hand, reflex action

    Growth, metabolism regulation

    🔹 Q12: What is the difference between the manner in which movement takes place in a sensitive plant and movement in our legs?

    Feature

    Movement in Sensitive Plant

    Movement in Human Legs

    Type of movement

    Nastic movement (non-directional)

    Voluntary movement

    Controlled by

    Plant cells (chemical signals)

    Nervous system and muscles

    Speed

    Relatively slow

    Fast

    Involves growth?

    No

    No

    Example

    Mimosa pudica folds on touch

    Walking, running

     


    https://youtube.com/shorts/bbEiF0BDzJ0?si=69Pg90RCclXCrxm9   


🧠 Mind Map 1: Control and Coordination in Animals

CONTROL & COORDINATION (Animals)

│

├── Nervous System

│   ├── Central Nervous System (CNS)

│   │   ├── Brain (Cerebrum, Cerebellum, Medulla)

│   │   └── Spinal Cord

│   ├── Peripheral Nervous System (PNS)

│   │   ├── Cranial Nerves

│   │   └── Spinal Nerves

│   └── Autonomic Nervous System

│       ├── Sympathetic (fight/flight)

│       └── Parasympathetic (rest/digest)

│

├── Neuron

│   ├── Dendrites → receive signal

│   ├── Cell body → process signal

│   ├── Axon → transmit signal

│   └── Axon terminals → synapse

│

├── Reflex Action

│   ├── Reflex Arc pathway

│   └── Involuntary, fast response

│

└── Brain

    ├── Cerebrum → intelligence, memory

    ├── Cerebellum → balance, coordination

    └── Medulla → involuntary actions

 

 

🧬 Mind Map 2: Endocrine System (Hormonal Control)

 

ENDOCRINE SYSTEM

│

├── Hormones = Chemical messengers

│

├── Endocrine Glands

│   ├── Pituitary → Growth Hormone, Master Gland

│   ├── Thyroid → Thyroxine (Metabolism)

│   ├── Pancreas → Insulin, Glucagon (Blood sugar)

│   ├── Adrenal → Adrenaline (Emergency hormone)

│   ├── Testes → Testosterone (male hormone)

│   └── Ovaries → Estrogen, Progesterone (female hormones)

│

└── Feedback Mechanism

    └── Maintains hormone balance

 

 🌿 Mind Map 3: Coordination in Plants

 

CONTROL & COORDINATION (Plants)

│

├── No Brain/Nerves → Use Hormones

│

├── Plant Movements

│   ├── Tropic (directional)

│   │   ├── Phototropism → light

│   │   ├── Geotropism → gravity

│   │   ├── Hydrotropism → water

│   │   ├── Thigmotropism → touch

│   │   └── Chemotropism → chemicals (pollen tube)

│   └── Nastic (non-directional)

│       └── e.g., Mimosa folding leaves

│

└── Plant Hormones

    ├── Auxin → cell elongation, phototropism

    ├── Gibberellin → stem growth, germination

    ├── Cytokinin → cell division

    ├── Abscisic Acid → inhibits growth, wilting

    └── Ethylene → fruit ripening

 


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