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Zoology Quiz

Zoology — +3 First Year, Semester I

The first-semester +3 (B.Sc.) zoology core paper is Animal Diversity of the Non-Chordates — from single-celled Protozoa up to the invertebrate phyla. These notes summarise each major group with its defining features and standard type examples, the way most CBCS/NEP universities frame the paper, followed by key terms and a practice set.

How Animals Are Classified

Animals are grouped into phyla using features such as symmetry, number of germ layers, body cavity (coelom), segmentation and level of organisation.

  • Levels of organisation: cellular (Porifera) → tissue (Coelenterata) → organ/organ-system (higher phyla).
  • Symmetry: asymmetrical, radial (Coelenterata, Echinodermata) or bilateral (most others).
  • Germ layers: diploblastic (two layers) vs triploblastic (three layers).
  • Body cavity: acoelomate, pseudocoelomate, or coelomate.

Protozoa (Protista)

Single-celled (acellular) eukaryotes that carry out all life functions within one cell. Standard type studies are Amoeba, Euglena and Paramecium.

  • Amoeba — moves and feeds using pseudopodia; reproduces by binary fission.
  • Euglena — green flagellate; both plant-like (photosynthesis) and animal-like nutrition (mixotrophic).
  • Paramecium — ciliate; feeds via oral groove; has two nuclei and shows conjugation.
  • Locomotory organelles to remember: pseudopodia, flagella and cilia.

Porifera and Coelenterata (Cnidaria)

  • Porifera (sponges): cellular level, pores (ostia) and canal system, choanocytes, spicules; e.g. Sycon, Euspongia, Euplectella.
  • Coelenterata: diploblastic, radial symmetry, tissue level, stinging cnidoblasts, polyp/medusa forms; e.g. Hydra, Obelia, Aurelia, Physalia.
  • Key term: polymorphism — different body forms (polyp and medusa) in one life cycle (e.g. Obelia).

The Worm Phyla

  • Platyhelminthes (flatworms): dorsoventrally flattened, acoelomate; many parasitic — Taenia (tapeworm), Fasciola, Schistosoma.
  • Nemathelminthes / Aschelminthes (roundworms): pseudocoelomate, unsegmented; Ascaris, Wuchereria (filaria), Ancylostoma (hookworm).
  • Annelida (segmented worms): true coelom, metameric segmentation; Nereis, Pheretima (earthworm), Hirudinaria (leech).

Arthropoda, Mollusca and Echinodermata

  • Arthropoda: largest phylum; jointed appendages, chitinous exoskeleton, moulting; e.g. prawn, cockroach, Scorpion.
  • Mollusca: soft body, muscular foot, mantle, often a shell; e.g. Pila, Unio, Sepia, Pearl oyster.
  • Echinodermata: marine, spiny skin, radial (five-fold) symmetry in adults, water-vascular system, tube feet; e.g. Starfish, Sea urchin.

Key Terms

Coelom
A true body cavity lined by mesoderm. Animals are acoelomate, pseudocoelomate or coelomate depending on how the cavity forms.
Diploblastic / Triploblastic
Having two (ectoderm + endoderm) or three (with mesoderm added) germ layers in the embryo.
Metameric segmentation
Division of the body into a series of similar segments, seen first in Annelida.
Water-vascular system
A system of fluid-filled canals and tube feet unique to Echinodermata, used in movement and feeding.

Practice Quiz — 8 Questions

correct out of 8

  1. Which locomotory organelle is used by Amoeba?

    • A.Cilia
    • B.Flagella
    • C.Pseudopodia
    • D.Tube feet
    C. Pseudopodia — Amoeba moves and feeds using temporary projections called pseudopodia.

  2. Coelenterates (Cnidaria) are:

    • A.Triploblastic and bilaterally symmetrical
    • B.Diploblastic and radially symmetrical
    • C.Acellular
    • D.Segmented worms
    B. Diploblastic and radially symmetrical — They have two germ layers and radial symmetry at the tissue level of organisation.

  3. Which phylum shows the cellular level of organisation with a canal system and spicules?

    • A.Porifera
    • B.Annelida
    • C.Mollusca
    • D.Echinodermata
    A. Porifera — Sponges (Porifera) have choanocytes, ostia and spicules at the cellular level.

  4. Taenia and Fasciola belong to which phylum?

    • A.Nemathelminthes
    • B.Platyhelminthes
    • C.Annelida
    • D.Arthropoda
    B. Platyhelminthes — These parasitic flatworms are Platyhelminthes.

  5. Metameric (true) segmentation is first seen in:

    • A.Platyhelminthes
    • B.Annelida
    • C.Porifera
    • D.Protozoa
    B. Annelida — Annelids such as the earthworm show true metameric segmentation.

  6. The largest animal phylum, with jointed legs and a chitinous exoskeleton, is:

    • A.Mollusca
    • B.Arthropoda
    • C.Echinodermata
    • D.Annelida
    B. Arthropoda — Arthropoda is the largest phylum; its name means 'jointed feet'.

  7. The water-vascular system with tube feet is characteristic of:

    • A.Mollusca
    • B.Echinodermata
    • C.Coelenterata
    • D.Annelida
    B. Echinodermata — Only echinoderms (e.g. starfish) possess a water-vascular system.

  8. Which protozoan is mixotrophic (both plant-like and animal-like nutrition)?

    • A.Amoeba
    • B.Paramecium
    • C.Euglena
    • D.Plasmodium
    C. Euglena — Euglena can photosynthesise and also take in food, so it is mixotrophic.

References

  • B.Sc. Zoology CBCS syllabus, Core Paper I — Animal Diversity (Non-Chordata), multiple Indian universities
  • Standard reference: Kotpal, Modern Text Book of Zoology — Invertebrates