1
1.
11TH GRADE
BIOLOGY
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Notes
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🐾 Detailed Notes on Animal Kingdom (NCERT Class 11)
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🔹 Introduction
●Animals are multicellular, eukaryotic, heterotrophic organisms.
They lack cell walls, unlike plants and fungi.
●Mode of nutrition is holozoic (ingestion, digestion, absorption).
●Most animals can move (locomotion) and have well-developed sensory and neuromotor
mechanisms.
, 2
●They reproduce sexually; development may be direct (young resembles adult) or
indirect (larval stages present)
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🔹 Basis of Classification
Animals are classified using the following criteria:
1. Levels of Organisation
Cellular (e.g., Porifera)
Tissue level (e.g., Cnidaria)
Organ system level (e.g., higher animals)
2. Body Symmetry
Asymmetrical (Porifera)
Radial (Cnidaria, Echinodermata adults)
Bilateral (Platyhelminthes → Chordates),(Echinodermata larva)
3. Germ Layers
Diploblastic (two layers: ectoderm + endoderm; e.g., Cnidaria)
Triploblastic (three layers: ectoderm + mesoderm + endoderm;
e.g., Platyhelminthes onwards)
4. Coelom (Body cavity)
Acoelomate (no coelom; e.g., flatworms)
1.
11TH GRADE
BIOLOGY
___
Notes
---
🐾 Detailed Notes on Animal Kingdom (NCERT Class 11)
—--------------------------------------------------------------------------------
🔹 Introduction
●Animals are multicellular, eukaryotic, heterotrophic organisms.
They lack cell walls, unlike plants and fungi.
●Mode of nutrition is holozoic (ingestion, digestion, absorption).
●Most animals can move (locomotion) and have well-developed sensory and neuromotor
mechanisms.
, 2
●They reproduce sexually; development may be direct (young resembles adult) or
indirect (larval stages present)
—--------------------------------------------------------------------------------
🔹 Basis of Classification
Animals are classified using the following criteria:
1. Levels of Organisation
Cellular (e.g., Porifera)
Tissue level (e.g., Cnidaria)
Organ system level (e.g., higher animals)
2. Body Symmetry
Asymmetrical (Porifera)
Radial (Cnidaria, Echinodermata adults)
Bilateral (Platyhelminthes → Chordates),(Echinodermata larva)
3. Germ Layers
Diploblastic (two layers: ectoderm + endoderm; e.g., Cnidaria)
Triploblastic (three layers: ectoderm + mesoderm + endoderm;
e.g., Platyhelminthes onwards)
4. Coelom (Body cavity)
Acoelomate (no coelom; e.g., flatworms)
