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| Animal Kingdom classification explained with levels of organisation and basic features in easy biology notes. |
Animal Kingdom Easy Notes for Students and NEET Aspirants
Animal Kingdom Notes (Easy Line-by-Line Explanation)
Chapter Introduction
Original Line:
“When you look around, you will observe different animals with different structures and forms.”
Easy Notes:
- Around us, many kinds of animals are present.
- All animals look different from each other.
- Their body shape, size, and structure are different.
Original Line:
“As over a million species of animals have been described till now…”
Easy Notes:
- Scientists have discovered and named more than 10 lakh animal species.
- Because animals are so many, studying them becomes difficult.
Original Line:
“The need for classification becomes all the more important.”
Easy Notes:
- Classification means grouping animals based on similarities.
- It helps us study animals easily and systematically.
Original Line:
“The classification also helps in assigning a systematic position to newly described species.”
Easy Notes:
- When a new animal is discovered, classification helps place it in the correct group.
- It tells us which animals are related to each other.
4.1 Basis of Classification
Original Line:
“Inspite of differences in structure and form of different animals…”
Easy Notes:
- Animals may look different externally.
- But many basic features are common among them.
Original Line:
“There are fundamental features common to various individuals…”
Easy Notes:
- Fundamental features = important basic characteristics.
- Scientists compare these characteristics for classification.
Original Line:
“Arrangement of cells…”
Easy Notes:
- Scientists check how cells are organized in the body.
Example:
- Loose cells → simple animals
- Organized cells → complex animals
Original Line:
“Body symmetry…”
Easy Notes:
- Symmetry means equal division of body parts.
Types:
- Bilateral symmetry → right and left halves equal
- Radial symmetry → body parts arranged around center
Original Line:
“Nature of coelom…”
Easy Notes:
- Coelom = body cavity present between body wall and gut.
- Animals are grouped based on whether coelom is present or absent.
Original Line:
“Patterns of digestive, circulatory or reproductive systems.”
Easy Notes:
- Scientists also study:
- Digestive system
- Blood circulation
- Reproductive system
These systems help identify animal groups.
Original Line:
“These features are used as the basis of animal classification.”
Easy Notes:
- All these characteristics are used to classify animals into groups.
4.1.1 Levels of Organisation
Original Line:
“Though all members of Animalia are multicellular…”
Easy Notes:
- All animals are made of many cells.
- But their cell organization differs.
Original Line:
“All of them do not exhibit the same pattern of organisation of cells.”
Easy Notes:
- Different animals have different levels of body organization.
Cellular Level of Organisation
Original Line:
“In sponges, the cells are arranged as loose cell aggregates…”
Easy Notes:
- In sponges, cells are loosely arranged.
- Cells are not fully organized into tissues.
Original Line:
“They exhibit cellular level of organisation.”
Easy Notes:
- This simple arrangement is called cellular level organization.
Meaning:
- Cells perform activities independently.
Original Line:
“Some division of labour occurs among the cells.”
Easy Notes:
- Different cells do different jobs.
- Example:
- Some cells digest food
- Some cells protect body
Tissue Level of Organisation
Original Line:
“In coelenterates, the arrangement of cells is more complex.”
Easy Notes:
- Coelenterates are more advanced than sponges.
- Their cells are better organized.
Original Line:
“Cells performing the same function are arranged into tissues.”
Easy Notes:
- Similar cells combine to form tissues.
- Each tissue performs a specific function.
Example:
- Muscle tissue
- Nerve tissue
Original Line:
“Hence is called tissue level of organisation.”
Easy Notes:
- This arrangement is called tissue level organization.
Organ Level of Organisation
Original Line:
“A still higher level of organisation i.e., organ level…”
Easy Notes:
- In more advanced animals, tissues combine to form organs.
Original Line:
“Exhibited by members of Platyhelminthes and higher phyla…”
Easy Notes:
- Flatworms and higher animals show organ level organization.
Original Line:
“Tissues are grouped together to form organs…”
Easy Notes:
- Different tissues join together to make organs.
Example:
- Heart
- Stomach
- Kidney
Original Line:
“Each specialised for a particular function.”
Easy Notes:
- Every organ performs a specific function.
Example:
- Heart pumps blood
- Stomach digests food
Quick Revision Points
- Classification helps study animals easily.
- Basis of classification:
- Cell arrangement
- Symmetry
- Coelom
- Organ systems
- Levels of organization:
- Cellular level → Sponges
- Tissue level → Coelenterates
- Organ level → Platyhelminthes and higher animals
Easy Mnemonic
Levels of Organisation
“C T O”
- C → Cellular
- T → Tissue
- O → Organ
Sentence Trick: “Cells Together Organize.”
ANIMAL KINGDOM
│
├── Importance of Classification
│ ├── More than 1 million animal species
│ ├── Helps in easy study
│ ├── Groups similar animals together
│ └── Helps place newly discovered species
│
├── Basis of Classification
│ │
│ ├── Arrangement of Cells
│ │ ├── Loose cells
│ │ └── Organized cells
│ │
│ ├── Body Symmetry
│ │ ├── Bilateral symmetry
│ │ └── Radial symmetry
│ │
│ ├── Nature of Coelom
│ │ ├── Coelom present
│ │ └── Coelom absent
│ │
│ ├── Digestive System
│ ├── Circulatory System
│ └── Reproductive System
│
└── Levels of Organisation
│
├── Cellular Level
│ ├── Found in Sponges
│ ├── Loose cell aggregates
│ └── Simple organisation
│
├── Tissue Level
│ ├── Found in Coelenterates
│ ├── Similar cells form tissues
│ └── More complex body structure
│
└── Organ Level
├── Found in Platyhelminthes & higher animals
├── Tissues combine to form organs
└── Each organ has specific function
CBSE Class 11 Biology Questions & Answers
Chapter: Animal Kingdom (Basis of Classification & Levels of Organisation)
1. MCQs (Multiple Choice Questions)
Q1. Classification of animals is important because:
A. Animals are very small
B. Animals are colorful
C. There are many animal species
D. Animals can fly
✅ Answer: C. There are many animal species
Q2. Sponges show:
A. Organ level organisation
B. Tissue level organisation
C. Cellular level organisation
D. Organ system level organisation
✅ Answer: C. Cellular level organisation
Q3. Tissue level organisation is seen in:
A. Sponges
B. Coelenterates
C. Platyhelminthes
D. Arthropods
✅ Answer: B. Coelenterates
Q4. Organ level organisation is first seen in:
A. Porifera
B. Coelenterata
C. Platyhelminthes
D. Mollusca
✅ Answer: C. Platyhelminthes
Q5. Coelom refers to:
A. Digestive cavity
B. Body cavity
C. Reproductive organ
D. Tissue cavity
✅ Answer: B. Body cavity
Q6. Similar cells grouped together form:
A. Organ
B. Tissue
C. System
D. Coelom
✅ Answer: B. Tissue
Q7. Animals with loose cell aggregates belong to:
A. Sponges
B. Arthropods
C. Molluscs
D. Echinoderms
✅ Answer: A. Sponges
Q8. Which feature is NOT used for animal classification?
A. Symmetry
B. Coelom
C. Color of animal
D. Organ system
✅ Answer: C. Color of animal
2. Very Short Answer Questions (1 Mark)
Q1. What is classification?
✅ Classification is the process of grouping organisms based on similarities and differences.
Q2. Define coelom.
✅ Coelom is the body cavity present between body wall and digestive tract.
Q3. Name the simplest level of organisation in animals.
✅ Cellular level organisation.
Q4. Which animals show tissue level organisation?
✅ Coelenterates.
Q5. Which phylum first shows organ level organisation?
✅ Platyhelminthes.
3. Short Answer Questions (2–3 Marks)
Q1. Why is classification important?
✅
- It makes study of animals easier.
- It groups similar animals together.
- It helps identify newly discovered species.
Q2. Differentiate between cellular and tissue level organisation.
| Cellular Level | Tissue Level |
|---|---|
| Cells loosely arranged | Cells form tissues |
| Seen in sponges | Seen in coelenterates |
| Simple organisation | More complex organisation |
Q3. What are the bases of animal classification?
✅ Animals are classified on the basis of:
- Arrangement of cells
- Symmetry
- Nature of coelom
- Digestive system
- Circulatory system
- Reproductive system
4. Long Answer Questions (5 Marks)
Q1. Explain different levels of organisation in animals.
✅ Answer:
1. Cellular Level Organisation
- Seen in sponges.
- Cells are loosely arranged.
- No true tissues formed.
2. Tissue Level Organisation
- Seen in coelenterates.
- Similar cells group together to form tissues.
3. Organ Level Organisation
- Seen in Platyhelminthes and higher animals.
- Tissues combine to form organs.
- Each organ performs a specific function.
Q2. Explain the basis of classification in animals.
✅ Answer: Animals are classified using the following features:
- Arrangement of cells
- Body symmetry
- Nature of coelom
- Digestive system
- Circulatory system
- Reproductive system
These features help scientists study animals systematically.
5. Assertion and Reason Questions
Q1.
Assertion (A):
Sponges show cellular level organisation.
Reason (R):
Cells in sponges are loosely arranged.
A. Both A and R are true and R is correct explanation
B. Both A and R are true but R is not correct explanation
C. A is true but R is false
D. A is false but R is true
✅ Answer: A
Q2.
Assertion (A):
Platyhelminthes show organ level organisation.
Reason (R):
Tissues combine together to form organs.
✅ Answer: A
6. Case Study Questions
Case Study 1
A scientist discovered a simple aquatic animal whose cells are loosely arranged and do not form tissues.
Q1. Which level of organisation is present?
✅ Cellular level organisation
Q2. Name the phylum.
✅ Porifera
Q3. Are true tissues present?
✅ No
Case Study 2
An animal has tissues grouped together to form organs.
Q1. Which level of organisation is present?
✅ Organ level organisation
Q2. Name one phylum showing this organisation.
✅ Platyhelminthes
Q3. Which is more advanced: tissue or organ level?
✅ Organ level
7. Statement-Based Questions
Q1. State True or False:
“Coelenterates show tissue level organisation.”
✅ True
Q2. State True or False:
“Sponges have well-developed organs.”
✅ False
Q3. State True or False:
“Classification helps in studying animals easily.”
✅ True
Q4. State True or False:
“All animals show same level of organisation.”
✅ False
8. Match the Columns
| Column A | Column B |
|---|---|
| 1. Sponges | A. Organ level |
| 2. Coelenterates | B. Cellular level |
| 3. Platyhelminthes | C. Tissue level |
✅ Answers:
1 → B
2 → C
3 → A
9. HOTS Questions
Q1. Why are organ level animals considered more advanced?
✅ Because organs perform specialized functions efficiently, making body organisation more complex and effective.
Q2. Why do scientists use body symmetry for classification?
✅ Because symmetry helps identify body structure and evolutionary relationships among animals.
Quick Revision Trick
Levels of Organisation
C → Cellular → Sponges
T → Tissue → Coelenterates
O → Organ → Platyhelminthes
Mnemonic:
“Cells Together Organize”
By- Dr.Sanjaykumar pawar
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