About the NDA/CDS 1 2026 Exam
The NDA (National Defence Academy) and CDS (Combined Defence Services) examinations are prestigious national-level exams conducted by the UPSC (Union Public Service Commission). They test candidates’ knowledge in Mathematics, English, and General Knowledge, including General Science. Biology plays an important role in the General Science section, where topics like Animal Kingdom are frequently tested to assess candidates’ understanding of basic zoological concepts.
Introduction to Animal Kingdom
The Animal Kingdom is one of the fundamental units of biological classification. It encompasses all multicellular, eukaryotic, heterotrophic organisms that exhibit locomotion and respond to stimuli. The study of this kingdom helps us understand the diversity, organization, and evolutionary relationships among different groups of animals.
Animals show wide diversity in structure, function, and habitat — from simple sponges to complex mammals — and their classification is based on body organization, symmetry, germ layers, coelom, segmentation, and mode of reproduction.
Major Subtopics Covered
- Basis of Classification
- Levels of organization: Cellular, tissue, organ, organ-system
- Symmetry: Asymmetrical, radial, bilateral
- Germ layers: Diploblastic and triploblastic organization
- Coelom: Acoelomate, pseudocoelomate, and coelomate animals
- Segmentation and notochord presence
- Non-Chordates
- Phylum Porifera – Sponges; simplest animals, canal system
- Phylum Coelenterata (Cnidaria) – Jellyfish, corals; cnidoblasts
- Phylum Platyhelminthes – Flatworms; parasitic forms like tapeworm
- Phylum Aschelminthes (Nematoda) – Roundworms; pseudocoelomates
- Phylum Annelida – Earthworm; true segmentation
- Phylum Arthropoda – Insects, spiders, crustaceans; largest phylum
- Phylum Mollusca – Snails, octopus; soft-bodied with shells
- Phylum Echinodermata – Starfish, sea urchins; radial symmetry in adults
- Chordates
- Characteristics of Chordates – Notochord, dorsal nerve cord, pharyngeal gill slits
- Subphylum Protochordata – Amphioxus, Balanoglossus
- Vertebrata (Craniata) – Well-developed brain and endoskeleton
- Pisces (Fishes)
- Amphibia (Frogs)
- Reptilia (Snakes, Lizards)
- Aves (Birds)
- Mammalia (Humans, Mammals)
- Evolutionary Relationships and Adaptations
- Trends in body complexity
- Transition from aquatic to terrestrial life
- Physiological and anatomical adaptations
Conclusion
The Animal Kingdom reflects the unity in diversity among living organisms. Studying it provides insight into the structural, functional, and evolutionary relationships across species. For NDA/CDS aspirants, mastering this topic builds a strong foundation in General Science and enhances analytical understanding required for defense services.
