What is Living? NCERT Biology Short Notes with Examples
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| What is Living? Easy NEET Biology notes explaining the five defining characteristics of living organisms. |
What is Living? – Short Notes for NEET
Living Organisms
Living organisms are those that grow, reproduce, perform metabolism, have cellular organisation, and respond to their surroundings (consciousness).
Main Characteristics of Living Organisms
1. Growth
- Growth means increase in size, mass, and number of cells.
- In living organisms, growth is internal (by cell division).
- In non-living things, growth is external (by accumulation of material).
- Example: Mountains and sand dunes grow by deposition.
NEET Point:
➡️ Growth alone is NOT a defining feature of living organisms because non-living things also show growth.
2. Reproduction
- Reproduction means producing new individuals of the same species.
- It occurs by:
- Sexual reproduction
- Asexual reproduction
Asexual Reproduction Examples
| Method | Example |
|---|---|
| Budding | Yeast, Hydra |
| Fragmentation | Filamentous algae, Moss protonema |
| Spores | Fungi |
| True regeneration | Planaria |
- In Amoeba, bacteria, and unicellular algae, growth = reproduction (cell divides to form new individuals).
Exceptions
- Mule
- Sterile worker bees
- Infertile human couples
These are living but do not reproduce.
NEET Point:
➡️ Reproduction is not a defining characteristic of all living organisms.
3. Metabolism
- Metabolism = Sum of all chemical reactions occurring inside the body.
- Includes:
- Anabolism (building up)
- Catabolism (breaking down)
Important
- Every living organism shows metabolism.
- Non-living things do not show metabolism.
NEET Point:
➡️ Metabolism is the defining feature of life without exception.
4. Cellular Organisation
- All living organisms are made up of cells.
- The cell is the basic structural and functional unit of life.
Important
- Metabolic reactions can occur outside the body (in a test tube), but they are living reactions, not living organisms.
- Therefore, cellular organisation is essential for life.
5. Consciousness (Response to Stimuli)
- Living organisms can sense and respond to changes in their environment.
- Stimuli may be:
- Physical
- Chemical
- Biological
Examples
- Plants bend towards light (phototropism).
- Plants respond to water, temperature, pollutants, etc.
- Animals respond to heat, sound, light, and danger.
Special Point
- Humans are the only organisms with self-consciousness (awareness of themselves).
NEET Point:
➡️ Consciousness (response to stimuli) is a defining property of living organisms.
NCERT Definition of Living Organisms
Living organisms are self-replicating, evolving, self-regulating interactive systems capable of responding to external stimuli.
NEET One-Liners (Very Important)
- Growth in living organisms → Internal
- Growth in non-living things → External
- Growth is not a defining property.
- Reproduction is not a defining property (exceptions: mule, sterile worker bees, infertile couples).
- Metabolism → Defining feature of life without exception.
- Cellular organisation → Defining feature of life.
- Consciousness (response to stimuli) → Defining property of living organisms.
- Humans alone possess self-consciousness.
- In Amoeba and bacteria, growth = reproduction.
Memory Trick
G-R-M-C-C
- G = Growth
- R = Reproduction
- M = Metabolism
- C = Cellular organisation
- C = Consciousness (response to stimuli)
Most Important NEET Fact:
Metabolism + Cellular Organisation + Consciousness = Best defining features of living organisms.
NEET Smart Notes – What is Living? (Copy Format)
🌿 WHAT IS LIVING?
📌 Characteristics of Living Organisms
| Characteristic | Living Organisms | Non-Living Objects | NEET Point |
|---|---|---|---|
| Growth | Internal (Cell Division) | External (Deposition) | ❌ Not Defining |
| Reproduction | Sexual & Asexual | Absent | ❌ Not Defining (Exceptions) |
| Metabolism | Present | Absent | ✅ Defining Feature |
| Cellular Organisation | Present | Absent | ✅ Defining Feature |
| Consciousness | Respond to Stimuli | No Response | ✅ Defining Property |
🧠 Flow Chart
LIVING ORGANISMS
│
──────────────────────────────────────
│ │ │ │
Growth Reproduction Metabolism Consciousness
│ │ │ │
Internal Sexual & Chemical Response to
Growth Asexual Reactions Stimuli
│ │ │ │
Not Exceptions Defining Defining
Defining Feature Property
🎯 Mnemonic
GRMCC
G → Growth
R → Reproduction
M → Metabolism
C → Cellular Organisation
C → Consciousness
Memory Sentence
"Great Rahul Makes Clever Choices."
⭐ Defining Features
| Feature | Defining? |
|---|---|
| Growth | ❌ No |
| Reproduction | ❌ No |
| Metabolism | ✅ Yes |
| Cellular Organisation | ✅ Yes |
| Consciousness | ✅ Yes |
Trick
MCC = King of Life
M → Metabolism
C → Cellular Organisation
C → Consciousness
🌱 Growth
Living Organisms
✔ Internal Growth
✔ Cell Division
✔ Increase in Cell Number
Non-Living
✔ External Growth
✔ Deposition of Material
Examples
• Mountain
• Sand Dune
NEET Point
Growth is NOT the defining property of life.
🌸 Reproduction
Types
Sexual
Asexual
| Method | Example |
|---|---|
| Budding | Yeast, Hydra |
| Fragmentation | Filamentous Algae, Moss Protonema |
| Spore Formation | Fungi |
| Regeneration | Planaria |
Exceptions
• Mule
• Sterile Worker Bee
• Infertile Human Couple
NEET Point
Reproduction is NOT a defining property of life.
⚡ Metabolism
Definition
Sum total of all chemical reactions occurring inside the body.
Important Points
✔ Present in all Living Organisms
✔ Absent in Non-Living Objects
✔ Defining Feature of Life
🧬 Cellular Organisation
• All living organisms are made up of cells.
• Cell is the structural and functional unit of life.
NEET Point
Cellular Organisation is a defining feature of life.
🌍 Consciousness
Meaning
Ability to sense and respond to environmental stimuli.
Stimuli
• Light
• Water
• Temperature
• Chemicals
• Other Organisms
Human Special Feature
✔ Self-Consciousness
NEET Point
Consciousness is a defining property of life.
📚 NCERT Definition
Living organisms are self-replicating, evolving, self-regulating interactive systems capable of responding to external stimuli.
🚨 NEET Exceptions
| Topic | Exception |
|---|---|
| Reproduction | Mule |
| Reproduction | Sterile Worker Bee |
| Reproduction | Infertile Human Couple |
| Growth = Reproduction | Amoeba |
| Growth = Reproduction | Bacteria |
| Growth = Reproduction | Unicellular Algae |
Mnemonic
MBA
M → Mule
B → Bee
A → Amoeba
⚠️ NEET Trap Questions
❌ Growth is the defining property of life.
✅ False
❌ All living organisms reproduce.
✅ False
✔ Metabolism is the defining feature of life.
✅ True
✔ Cellular Organisation is essential for life.
✅ True
✔ Consciousness means response to stimuli.
✅ True
⚡ 30-Second Revision
✅ Growth → Internal → ❌ Not Defining
✅ Reproduction → Exceptions → ❌ Not Defining
✅ Metabolism → ✅ Defining Feature
✅ Cellular Organisation → ✅ Defining Feature
✅ Consciousness → ✅ Defining Property
✅ Humans → Self-Conscious
✅ Amoeba → Growth = Reproduction
🎯 Ultimate Memory Formula
GRMCC
Growth → Reproduction → Metabolism → Cellular Organisation → Consciousness
Remember:
❌ G + R = Not Defining
✅ M + C + C = Defining Features of Life
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