Kingdom Monera Explained for NEET: Bacteria, Types & Examples

 Kingdom Monera Notes for NEET Biology: Simple & Easy Revision

Kingdom Monera showing different bacterial shapes and types including archaebacteria, eubacteria, and cyanobacteria in diverse habitats.

- Dr.Sanjaykumar Pawar 

When we study the classification of living organisms, one of the most fundamental groups is Kingdom Monera. It includes the simplest and most primitive life forms on Earth—bacteria. Despite their tiny size, bacteria are extremely important for life processes, ecosystems, and even human industries.

---

🌍 What is Kingdom Monera?

Kingdom Monera consists of all bacteria. These organisms are unicellular (single-celled), prokaryotic, and lack a well-defined nucleus.

They are considered:

• The oldest living organisms
• The most abundant organisms on Earth
• Found in almost every environment, including extreme habitats

---

🌱 Where are bacteria found?

Bacteria are truly everywhere. They can survive in:

• Soil (in huge numbers)
• Water bodies
• Air
• Inside living organisms
• Extreme environments like:
  • Hot springs 🌋
  • Salt lakes 🧂
  • Deep oceans 🌊
  • Snow-covered regions ❄️

Some bacteria also live as parasites, depending on other organisms for survival.

---

🔬 Shapes of Bacteria (Very Important for NEET)

Bacteria are classified based on their shape:

• Coccus (cocci) → spherical or round
• Bacillus (bacilli) → rod-shaped
• Vibrio → comma-shaped
• Spirillum (spirilla) → spiral-shaped

This simple classification is often asked in exams and helps in identification.

---

⚡ Metabolic Diversity: Their Hidden Strength

Even though bacteria look simple, they show huge metabolic diversity.

They can be:

🌿 Autotrophic bacteria

These bacteria prepare their own food:

• Photosynthetic autotrophs → use sunlight (like plants)
• Chemosynthetic autotrophs → use energy from chemical reactions

🍂 Heterotrophic bacteria (majority)

• Cannot make their own food
• Depend on dead or living organic matter
• Act as decomposers in nature

---

🔥 Archaebacteria: Survivors of Extreme Conditions

Archaebacteria are special bacteria that live in harsh environments where most life cannot survive.

They include:

• Halophiles → live in high salt areas
• Thermoacidophiles → live in hot acidic springs
• Methanogens → live in marshy areas

🧪 Important fact:

Methanogens are found in the stomach of cows and buffaloes, where they help produce methane gas (biogas) from dung. This makes them important for renewable energy.

---

🌿 Eubacteria: True Bacteria

Eubacteria are the largest and most common group of bacteria, also called “true bacteria”.

Key features:

• Have a rigid cell wall
• Some have flagella for movement
• Found everywhere in nature

---

🌊 Cyanobacteria (Blue-Green Algae)

Cyanobacteria are special photosynthetic bacteria.

They:

• Contain chlorophyll a (like green plants)
• Can prepare their own food using sunlight
• May be unicellular, colonial, or filamentous

Examples include:

• Nostoc
• Anabaena

🌱 Special feature:

Some cyanobacteria have heterocysts, specialized cells that help in nitrogen fixation.

---

🌍 Role in nature:

• Help recycle nutrients like nitrogen, phosphorus, iron, and sulfur
• Some form blooms in polluted water bodies

---

💡 Importance of Bacteria

👍 Useful roles:

• Help in making curd from milk
• Production of antibiotics
• Nitrogen fixation in legume roots
• Act as decomposers

👎 Harmful roles:

Some bacteria cause diseases like:

• Cholera
• Typhoid
• Tetanus
• Citrus canker (in plants)

---

🔁 Reproduction in Bacteria

Bacteria mainly reproduce by:

1. Binary Fission

• One cell divides into two identical cells
• Very fast method of reproduction

2. Spore Formation

• Occurs in unfavorable conditions
• Helps bacteria survive harsh environments

3. Genetic Transfer

• Exchange of DNA between bacteria
• Not true sexual reproduction but increases variation

---

🧬 Mycoplasma: The Unique Bacteria

Mycoplasma are very special because:

• They lack a cell wall
• Are the smallest living organisms
• Can survive without oxygen
• Many are pathogenic

---

📌 Conclusion

Kingdom Monera shows how even the simplest organisms can be incredibly diverse and powerful. From surviving in extreme environments to playing major roles in ecosystems and industry, bacteria are essential for life on Earth.

For NEET students, this chapter is important because it includes classification, examples, and key biological processes that are frequently asked in exams.

 Kingdom Monera

│

├── General Characteristics

│   ├── Sole members → Bacteria

│   ├── Most abundant microorganisms

│   ├── Found almost everywhere

│   │   ├── Soil

│   │   ├── Water

│   │   ├── Air

│   │   ├── On/In living organisms

│   │   └── Extreme habitats

│   └── Some are parasites

│

├── Types Based on Shape

│   ├── Coccus → Spherical

│   ├── Bacillus → Rod-shaped

│   ├── Vibrio → Comma-shaped

│   └── Spirillum → Spiral-shaped

│

├── Nutrition

│   ├── Autotrophic

│   │   ├── Photosynthetic

│   │   └── Chemosynthetic

│   └── Heterotrophic

│       ├── Depend on living organisms

│       └── Feed on dead organic matter

│

├── Types of Bacteria

│   │

│   ├── Archaebacteria

│   │   ├── Live in extreme habitats

│   │   │   ├── Halophiles → Salty areas

│   │   │   ├── Thermoacidophiles → Hot springs

│   │   │   └── Methanogens → Marshy areas

│   │   ├── Different cell wall structure

│   │   └── Importance

│   │       ├── Present in gut of cows & buffaloes

│   │       └── Produce methane (Biogas)

│   │

│   └── Eubacteria (True Bacteria)

│       ├── Rigid cell wall

│       ├── Flagellum (if motile)

│       ├── Cyanobacteria (Blue-green algae)

│       │   ├── Chlorophyll-a

│       │   ├── Photosynthetic autotrophs

│       │   ├── Unicellular / Colonial / Filamentous

│       │   ├── Freshwater / Marine / Terrestrial

│       │   ├── Gelatinous sheath

│       │   ├── Form blooms in polluted water

│       │   └── Nitrogen fixation

│       │       ├── Heterocysts

│       │       ├── Nostoc

│       │       └── Anabaena

│       ├── Chemosynthetic bacteria

│       │   ├── Oxidize inorganic substances

│       │   │   ├── Nitrates

│       │   │   ├── Nitrites

│       │   │   └── Ammonia

│       │   ├── Produce ATP

│       │   └── Recycle nutrients

│       │       ├── Nitrogen

│       │       ├── Phosphorus

│       │       ├── Iron

│       │       └── Sulphur

│       └── Heterotrophic bacteria

│           ├── Most abundant

│           ├── Decomposers

│           ├── Useful

│           │   ├── Curd making

│           │   ├── Antibiotic production

│           │   └── Nitrogen fixation in legumes

│           └── Harmful (Pathogens)

│               ├── Cholera

│               ├── Typhoid

│               ├── Tetanus

│               └── Citrus canker

│

├── Reproduction

│   ├── Binary fission (Main method)

│   ├── Spore formation

│   │   └── During unfavourable conditions

│   └── Primitive sexual reproduction

│       └── DNA transfer between bacteria

│

└── Mycoplasma

    ├── Lack cell wall

    ├── Smallest living cells

    ├── Can survive without oxygen

    └── Many are pathogenic to plants and animals 

complete CBSE Class 11 NEET/CBSE exam practice set from Kingdom Monera (Bacteria) including all question types.

---

🦠 KINGDOM MONERA – QUESTION BANK (CBSE CLASS 11)

---

✅ 1. VERY SHORT ANSWER QUESTIONS (1 MARK)

Q1. What is Kingdom Monera?

Ans: Kingdom Monera includes all prokaryotic organisms like bacteria.

---

Q2. What is the shape of Spirillum?

Ans: Spiral-shaped bacteria.

---

Q3. Name the smallest living organism.

Ans: Mycoplasma.

---

Q4. What is the mode of reproduction in bacteria?

Ans: Binary fission.

---

Q5. What is a heterocyst?

Ans: A specialized nitrogen-fixing cell in cyanobacteria.

---

Q6. Name one methanogen.

Ans: Methanobacterium.

---

Q7. Do bacteria have a true nucleus?

Ans: No.

---

Q8. What is the cell wall of Mycoplasma?

Ans: Absent.

---

✍️ 2. SHORT ANSWER QUESTIONS (2–3 MARKS)

Q1. Write any three characteristics of bacteria.

Ans:

• Unicellular and prokaryotic
• Reproduce by binary fission
• Present everywhere in nature

---

Q2. Differentiate between autotrophic and heterotrophic bacteria.

Ans:

• Autotrophic: Prepare their own food (photosynthetic/chemosynthetic)
• Heterotrophic: Depend on other organisms for food

---

Q3. What are archaebacteria? Give examples.

Ans:

• Bacteria living in extreme conditions
• Examples: Halophiles, Thermoacidophiles, Methanogens

---

Q4. What is the role of cyanobacteria?

Ans:

• Photosynthesis
• Nitrogen fixation
• Improve soil fertility

---

Q5. Why are bacteria important in nature?

Ans:

• Decomposition
• Nutrient recycling
• Food production (curd, antibiotics)

---

📘 3. LONG ANSWER QUESTIONS (5 MARKS)

---

Q1. Explain the classification of bacteria based on shape.

Ans: Bacteria are classified into four types:

• Coccus: spherical
• Bacillus: rod-shaped
• Vibrio: comma-shaped
• Spirillum: spiral-shaped
  This classification helps in identification and study of bacteria.

---

Q2. Describe Archaebacteria in detail.

Ans: Archaebacteria are ancient bacteria found in extreme environments:

• Halophiles → salty areas
• Thermoacidophiles → hot acidic springs
• Methanogens → marshy areas
  They have a unique cell wall and can survive harsh conditions.

---

Q3. Explain the importance of bacteria.

Ans:

• Helpful in nitrogen fixation
• Used in curd and antibiotic production
• Decompose organic matter
• Some are harmful pathogens causing diseases

---

🧠 4. MCQs (MULTIPLE CHOICE QUESTIONS)

---

Q1. Bacteria belong to:

A. Protista
B. Monera
C. Fungi
D. Plantae
Ans: B

---

Q2. Cyanobacteria perform:

A. Respiration
B. Photosynthesis
C. Digestion
D. Fermentation
Ans: B

---

Q3. Methanogens are found in:

A. Desert
B. Cow stomach
C. Ocean
D. Air
Ans: B

---

Q4. Mycoplasma lacks:

A. DNA
B. Ribosome
C. Cell wall
D. Cytoplasm
Ans: C

---

Q5. Binary fission is a type of:

A. Sexual reproduction
B. Asexual reproduction
C. Vegetative reproduction
D. Fragmentation
Ans: B

---

⚖️ 5. ASSERTION–REASON QUESTIONS

---

Q1.

Assertion (A): Mycoplasma can survive without oxygen.
Reason (R): They lack a cell wall.

A. Both true, R explains A
B. Both true, R not explanation
C. A true, R false
D. A false, R true
Ans: C

---

Q2.

A: Cyanobacteria fix nitrogen.
R: They have heterocysts.

Ans: A

---

Q3.

A: Bacteria show little diversity.
R: They have simple metabolism.

Ans: D (Both false)

---

🧩 6. FILL IN THE BLANKS

---

Q1. Bacteria reproduce by ________.

Ans: Binary fission

---

Q2. Blue-green algae are called ________.

Ans: Cyanobacteria

---

Q3. Methanogens produce ________ gas.

Ans: Methane

---

Q4. Spirally shaped bacteria are called ________.

Ans: Spirillum

---

Q5. Mycoplasma lacks ________.

Ans: Cell wall

---

🔗 7. MATCH THE COLUMNS

---

Column A

1. Coccus
2. Bacillus
3. Vibrio
4. Spirillum

Column B

A. Spiral
B. Rod
C. Spherical
D. Comma

Ans: 1 → C
2 → B
3 → D
4 → A

---

Column A

1. Methanogen
2. Cyanobacteria
3. Mycoplasma
4. Eubacteria

Column B

A. No cell wall
B. Photosynthesis
C. True bacteria
D. Biogas production

Ans: 1 → D
2 → B
3 → A
4 → C

---

📊 8. CASE STUDY QUESTION

---

Case Study:

A group of students studied microorganisms found in extreme environments. They found organisms in hot springs, salt lakes, and cow stomachs. Some bacteria were found to produce methane gas. Another group of bacteria showed no cell wall and were the smallest living organisms.

---

Q1. Which group survives in extreme environments?

Ans: Archaebacteria

---

Q2. Name bacteria producing methane.

Ans: Methanogens

---

Q3. Which organism lacks a cell wall?

Ans: Mycoplasma

---

Q4. Why are methanogens important?

Ans: They produce biogas from dung.

---

Q5. What is the smallest living organism?

Ans: Mycoplasma

🔗 Internal Links 

/biology/kingdom-monera-notes

/biology/bacterial-cells-structure

/biology/archaebacteria-vs-eubacteria

/biology/cyanobacteria-nitrogen-fixation

/neet/biology-important-chapters

/biology/microorganisms-classification

/biology/reproduction-in-bacteria