Control and Coordination – Concept Booster | Class 10 Science CBSE

Q: Imagine seeing a tiger. Your nervous system triggers your Adrenal glands to dump Adrenaline into your blood. This single hormone prepares your entire body simultaneously: The heart beats faster (pumping more oxygen), blood is diverted away from the digestive system and skin towards the skeletal muscles (to run or fight), and the breathing rate increases. This is why chemical coordination is needed—a single chemical can orchestrate a massive, body-wide response that electrical nerves couldn’t coordinate fast enough alone.

(a) Auxins: Synthesized at the shoot tip, help the cells to grow longer.(b) Gibberellins: Help in the growth of the stem.(c) Cytokinins: Promote cell division, present in high concentrations in fruits and seeds.(d) Abscisic Acid: A growth inhibitor, responsible for the wilting and falling of leaves.

Last modified on:50 minutes ago
Reading Time:17Minutes

Home Concept Boosters CBSE CBSE Class 10 Science Control & Coordination

Table of Contents

📖

How to Use This Page

Read each concept carefully, then check the formula, common mistake, and exam tip before moving to the next. This page completely covers Control and Coordination for CBSE Class 10 Science, exploring how multicellular organisms communicate internally to respond to their environment.

Key Concepts

Class 10 · Science · Biology

💡

Internal Communication

Nerves, Brains, and Chemical Messengers

Class 10 · Ch 7

The Neuron (Nerve Cell) Structure

The structural and functional unit of the nervous system.
Dendrites: Acquire information.
Cell Body & Axon: Conduct electrical impulses.
Nerve Ending: Passes the signal to the next cell.

The Synapse Concept

The microscopic gap between two neurons. Electrical signals cannot jump this gap. Instead, the electrical signal triggers the release of chemical neurotransmitters, which cross the gap and start a new electrical signal in the next neuron.

$$\text{Electrical } \rightarrow \text{ Chemical } \rightarrow \text{ Electrical}$$

Reflex Action & Reflex Arc Pathway

A sudden, involuntary, and rapid response to a stimulus. The pathway taken by the nerve impulses is a Reflex Arc, which bypasses the thinking part of the brain to save time.

$$\text{Receptor} \rightarrow \text{Sensory Neuron} \rightarrow \text{Spinal Cord} \rightarrow \text{Motor Neuron} \rightarrow \text{Effector (Muscle)}$$

The Human Brain Divisions

Forebrain: Main thinking part (Cerebrum), controls voluntary actions, memory, sensory processing.
Midbrain: Controls involuntary actions like pupil size.
Hindbrain: Controls involuntary actions. Cerebellum (posture, balance), Medulla (heartbeat, breathing), Pons.

Plant Movements (Tropic) Directional

Growth movements occurring in the direction of, or away from, a stimulus.
Phototropism: Light (shoots grow towards, roots away).
Geotropism: Gravity (roots towards, shoots away).
Hydrotropism: Water. Chemotropism: Chemicals (Pollen tube towards ovule).

Plant Movements (Nastic) Non-directional

Immediate responses to a stimulus where the direction of movement does not depend on the direction of the stimulus. Example: Drooping of leaves of the “Touch-me-not” plant (Mimosa pudica) due to changes in turgor pressure.

Phytohormones (Plant Hormones) Chemicals

Auxins: Cell elongation, synthesized at shoot tips.
Gibberellins: Growth of the stem.
Cytokinins: Promote rapid cell division (fruits/seeds).
Abscisic Acid (ABA): Inhibits growth, causes wilting of leaves (stress hormone).

Human Endocrine System Glands

A system of ductless glands that secrete hormones directly into the bloodstream to coordinate target organs. It is slower than the nervous system but affects cells system-wide and its effects last longer.

Major Human Hormones Functions

Thyroxine (Thyroid): Regulates carbohydrate/fat metabolism.
Growth Hormone (Pituitary): Regulates overall growth.
Adrenaline (Adrenal): “Fight or flight” response.
Insulin (Pancreas): Lowers blood sugar levels.

Feedback Mechanism Concept

A self-regulating mechanism ensuring hormones are secreted in precise quantities. For example, high blood sugar stimulates insulin secretion. When sugar drops, insulin secretion automatically stops.

Concept Deep Dive

The Mechanism of Phototropism

Why do plants bend towards the light?

Core Biological Process

When sunlight hits a plant from directly above, the hormone Auxin diffuses evenly down the stem, causing straight, upward growth.

But when light comes from only one side, Auxin hates light! It diffuses and accumulates on the shaded side of the shoot. Because Auxin promotes cell elongation, the cells on the shaded side grow longer and faster than the cells on the lit side. This unequal growth forces the entire stem to bend towards the light!

The “Fight or Flight” Emergency

Adrenaline takes over

Crucial Understanding

Imagine seeing a tiger. Your nervous system triggers your Adrenal glands to dump Adrenaline into your blood.

This single hormone prepares your entire body simultaneously: The heart beats faster (pumping more oxygen), blood is diverted away from the digestive system and skin towards the skeletal muscles (to run or fight), and the breathing rate increases. This is why chemical coordination is needed—a single chemical can orchestrate a massive, body-wide response that electrical nerves couldn’t coordinate fast enough alone.

Compare & Contrast

✗ Nervous Coordination

Information sent as electrical impulses.
Transmitted via highly specialized nerve cells (neurons).
Transmission is extremely rapid (milliseconds).
Effects are short-lived.
Only reaches specific target cells connected by nerves.

✓ Hormonal (Endocrine) Coordination

Information sent as chemical messengers (hormones).
Transmitted via the bloodstream.
Transmission is relatively slow.
Effects are prolonged and sustained.
Reaches all cells of the body, though only specific “target organs” respond.

◆

Remember

Sensory neurons carry signals IN (from receptors to the brain/spinal cord). Motor neurons carry signals OUT (from the brain/spinal cord to the muscles/glands).

Common Mistakes to Avoid

✗

Mistake 1

Cerebrum vs Cerebellum: They sound similar but do very different things.
The Cerebrum (Forebrain) is the big, wrinkly part where you think, learn, and decide.
The Cerebellum (Hindbrain) is the small structure at the back that handles physical balance, posture, and precision (like riding a bicycle or threading a needle).

✗

Mistake 2

Confusing Direction of Signal in a Neuron: An electrical impulse always travels in one specific direction: Dendrite $\rightarrow$ Cell Body $\rightarrow$ Axon $\rightarrow$ Nerve Ending. It never travels backward because the neurotransmitter vesicles are only present at the nerve endings.

✗

Mistake 3

Misunderstanding Iodine and Thyroid: Students often just say “iodine cures goiter”. Be precise: Iodine is absolutely essential for the thyroid gland to synthesize thyroxine hormone. A deficiency in iodine leads to a deficiency in thyroxine, causing the thyroid gland to swell (Goiter).

Exam Tips

✦

Tip 1

The “Tropic vs Nastic” Distinguisher: If an exam asks to differentiate between the folding of a Touch-me-not plant and the bending of a shoot toward light, focus on Direction and Growth. Phototropism is directional and involves growth. The Touch-me-not response is non-directional, independent of the direction of touch, and does not involve growth.

✦

Tip 2

Draw the Reflex Arc: A simple, well-labeled box diagram of the Reflex Arc (Receptor $\rightarrow$ Sensory Nerve $\rightarrow$ Spinal Cord $\rightarrow$ Motor Nerve $\rightarrow$ Effector) is the single most high-yield drawing for this chapter. Practice it!

Expected Exam Questions

Board Pattern Questions

Class 10 · Science · CBSE Exam

Class 10 · Biology

How does a synapse ensure that nerve impulses travel only in one direction? [2 marks]

Answer Neurotransmitters are only released from the axon terminal. 📝

Explanation

At a synapse, the chemical neurotransmitters are stored in vesicles located only at the axon terminal (nerve ending) of the pre-synaptic neuron. The receptors for these chemicals are located only on the dendrites of the post-synaptic neuron. Since chemicals can only be released from one side and detected on the other, the signal can only travel forward.

Name the plant hormones responsible for the following:
(a) Elongation of cells
(b) Growth of stem
(c) Promotion of cell division
(d) Falling of senescent leaves [2 marks]

Answer (a) Auxin, (b) Gibberellin, (c) Cytokinin, (d) Abscisic Acid. 📝

Explanation

(a) Auxins: Synthesized at the shoot tip, help the cells to grow longer.
(b) Gibberellins: Help in the growth of the stem.
(c) Cytokinins: Promote cell division, present in high concentrations in fruits and seeds.
(d) Abscisic Acid: A growth inhibitor, responsible for the wilting and falling of leaves.

Why is it advised to use iodized salt in our diet? Name the disease caused by its deficiency. [2 marks]

Answer Iodine is needed for Thyroxine synthesis. Deficiency causes Goiter. 📝

Explanation

Iodine is an essential mineral required by the thyroid gland to synthesize Thyroxine hormone. Thyroxine regulates carbohydrate, protein, and fat metabolism in the body to provide the best balance for growth. A deficiency of iodine in our diet reduces thyroxine production, causing the thyroid gland to swell—a disease known as Goiter (characterized by a swollen neck).

Concept Map

Control and Coordination connects to →

Human Biology

Life Processes (Regulating heart/lungs)

Reproduction (Testosterone/Estrogen hormones)

Heredity (Genetics dictating brain structure)

Control and Coordination – Concept Booster | Class 10 Science CBSE

Key Concepts

Internal Communication