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🔬 Biology  ·  Animal Kingdom  ·  NEET

Mammary glands, hair on skin, and a four-chambered heart are characteristic features of which class?

Answer: Mammalia.

  • A Aves
  • B Reptilia
  • C Mammalia
  • D Amphibia

Correct answer: C. Mammalia

Explanation: Mammalia is characterized by mammary glands for nourishing young, hair on the skin, sweat and oil glands, and a four-chambered heart.

Body Plan Progression Across PhylaPoriferaasymmetricalcellular levelCnidariaradial, diploblastictissue levelPlatyhelminthesbilateral, acoelomateorgan levelNematodapseudocoel.Annelida+true coelomorgan systemEach step adds organisational complexity: symmetry → germ layers → coelom type → organ systems

Moving across the animal phyla, body organisation becomes progressively more complex: from no symmetry and cellular organisation (Porifera) through radial/diploblastic (Cnidaria), bilateral/acoelomate (Platyhelminthes), pseudocoelomate (Nematoda), to a true coelom with full organ systems (Annelida and beyond).

Concept context

Phylum-level classification of the animal kingdom from Porifera to Chordata, based on body symmetry, coelom, and segmentation. One of the most example-heavy chapters for NEET.

Read the full Animal Kingdom notes →