NEET Physics: Waves – NCERT Masterclass & 100 MCQ Quiz

ANIMAL KINGDOM

NCERT Masterclass & NEET Biology Study Module

1. Basis of Classification

Animals are classified based on common fundamental features such as arrangement of cells, body symmetry, nature of coelom, and patterns of digestive, circulatory, or reproductive systems.

• Levels of Organisation: Cellular level (Porifera), Tissue level (Coelenterata, Ctenophora), Organ level (Platyhelminthes), Organ system level (Aschelminthes to Chordates).
• Symmetry: Asymmetrical (Sponges), Radial symmetry (Coelenterates, Ctenophores, Adult Echinoderms), Bilateral symmetry (Annelids, Arthropods, etc.).
• Diploblastic & Triploblastic: Diploblastic animals have two germ layers (ectoderm and endoderm) with an undifferentiated mesoglea (e.g., Coelenterates). Triploblastic have a third layer, mesoderm (from Platyhelminthes to Chordates).
• Coelom (Body Cavity):
  • Acoelomates: No body cavity (Platyhelminthes).
  • Pseudocoelomates: Mesoderm is present as scattered pouches (Aschelminthes).
  • Coelomates: True body cavity lined by mesoderm (Annelids, Molluscs, Arthropods, Echinoderms, Hemichordates, Chordates).

2. Non-Chordates (Phylum Porifera to Hemichordata)

🔥 NEET Pro-Tips on Key Phylum Features:

• Porifera (Sponges): Water canal system. Central cavity is spongocoel lined by Choanocytes (collar cells).
• Coelenterata (Cnidaria): Have Cnidoblasts for defense. Show two forms: Polyp (sessile, cylindrical e.g., Hydra) and Medusa (umbrella-shaped, free-swimming e.g., Aurelia). Metagenesis (Alternation of generation) seen in Obelia.
• Ctenophora: Sea walnuts or comb jellies. Possess 8 external rows of ciliated comb plates. Exhibit Bioluminescence. Only sexual reproduction.
• Platyhelminthes: Flatworms. Acoelomate. Have Flame cells for osmoregulation and excretion. E.g., Taenia (Tapeworm), Fasciola (Liver fluke).
• Aschelminthes: Roundworms. Pseudocoelomate. Muscular pharynx. E.g., Ascaris (Roundworm), Wuchereria (Filaria worm).
• Annelida: Metameric segmentation. Have longitudinal and circular muscles. Aquatic forms like Nereis possess lateral appendages called parapodia. Excretion by Nephridia.
• Arthropoda: Largest phylum. Jointed appendages, chitinous exoskeleton. Respiratory organs: gills, book gills, book lungs, tracheal system. Excretion by Malpighian tubules. E.g., Apis (Honey bee), Bombyx, Culex, Limulus (King crab - living fossil).
• Mollusca: Second largest. Unsegmented with head, muscular foot, visceral hump. Covered by calcareous shell. File-like rasping organ in mouth called radula.
• Echinodermata: Spiny bodied. Calcareous ossicles endoskeleton. Adults are radially symmetrical but larvae are bilaterally symmetrical. Unique Water Vascular System.
• Hemichordata: Worm-like marine animals. Body has proboscis, collar, and trunk. Rudimentary structure in collar region called stomochord (similar to notochord). Excretion by proboscis gland.

3. Phylum Chordata

Chordates are fundamentally characterized by the presence of a notochord, a dorsal hollow nerve cord, and paired pharyngeal gill slits. They have a post-anal tail and a closed circulatory system.

Phylum Chordata is divided into three subphyla:

1. Urochordata (Tunicata): Notochord is present ONLY in the larval tail (e.g., Ascidia, Salpa, Doliolum).
2. Cephalochordata: Notochord extends from head to tail region and is persistent throughout life (e.g., Branchiostoma/Amphioxus).
3. Vertebrata: Notochord is present during the embryonic period and is replaced by a cartilaginous or bony vertebral column in the adult. "All vertebrates are chordates but all chordates are not vertebrates."

4. Classes of Vertebrata

Vertebrata $\rightarrow$ Agnatha (Lacks jaw) $\rightarrow$ Class Cyclostomata
Vertebrata $\rightarrow$ Gnathostomata (Bears jaw) $\rightarrow$ Superclass Pisces & Tetrapoda

• Cyclostomata: Ectoparasites on some fishes. Circular, jawless mouth. Devoid of scales. E.g., Petromyzon (Lamprey), Myxine (Hagfish).
• Chondrichthyes (Cartilaginous Fishes): Marine, streamlined body. Mouth is ventral. Gills lack operculum. Skin has placoid scales. Absense of air bladder obligates them to swim constantly to avoid sinking. E.g., Scoliodon (Dog fish), Carcharodon (Great white shark).
• Osteichthyes (Bony Fishes): Marine and freshwater. Mouth is mostly terminal. 4 pairs of gills covered by an operculum. Scales are cycloid/ctenoid. Presence of air bladder regulates buoyancy. E.g., Hippocampus (Sea horse), Labeo (Rohu).
• Amphibia: Can live in aquatic as well as terrestrial habitats. Body is divided into head and trunk. Skin is moist (without scales). Heart is 3-chambered. E.g., Bufo (Toad), Rana (Frog), Ichthyophis (Limbless amphibia).
• Reptilia: Creeping/crawling mode of locomotion. Dry, cornified skin with epidermal scales or scutes. Heart is usually 3-chambered (4-chambered in crocodiles). E.g., Chelone (Turtle), Naja (Cobra).
• Aves (Birds): Presence of feathers, ability to fly (except flightless birds like Ostrich). Forelimbs modified into wings. Long bones are hollow with air cavities (pneumatic). Digestive tract has crop and gizzard. Heart is 4-chambered. Warm-blooded (Homoiothermous). E.g., Corvus (Crow), Pavo (Peacock).
• Mammalia: Most unique characteristic is the presence of milk-producing glands (mammary glands). Have hair on skin, external ears (pinnae). Different types of teeth in jaw. Mostly viviparous. E.g., Ornithorhynchus (Platypus - Oviparous exception), Macropus (Kangaroo), Homo (Man).

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🚀 NEET ANIMAL KINGDOM MEGA QUIZ (100 MCQ)

Solve the 5 parts below to master classification, non-chordates, and vertebrates.

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