Animal Kingdom – Class 11 Biology Complete Notes with MCQs

Animal Kingdom – Class 11 Biology Complete Notes with MCQs

Animal Kingdom – Class 11 Biology Notes

Introduction to the Animal Kingdom

The Animal Kingdom consists of diverse organisms ranging from microscopic invertebrates to the largest animals on Earth. Animals are multicellular, eukaryotic organisms that are heterotrophic (obtain food by ingestion). They exhibit a high degree of mobility and have specialized sense organs, nervous and muscular systems, making them capable of complex interactions with their environment.

Classification of the Animal Kingdom

The Animal Kingdom is classified into two major subgroups:

  1. Invertebrates – Animals without a backbone
  2. Vertebrates – Animals with a backbone

The animal kingdom is further divided into several phyla based on various characteristics, such as body symmetry, the presence of a body cavity, and segmentation.

Major Phyla of the Animal Kingdom

1. Phylum Porifera (Sponges)

Key Characteristics:

  • Symmetry: Asymmetrical or radially symmetrical
  • Body Organization: Cellular level of organization (no true tissues or organs)
  • Habitat: Mostly marine, some freshwater
  • Body Structure: Body contains pores (ostia) through which water flows
  • Reproduction: Both sexual (by gametes) and asexual (by budding)
  • Excretion: Diffusion

Examples:

  • Sponges (e.g., Spongilla, Euspongia)

2. Phylum Coelenterata (Cnidaria)

Key Characteristics:

  • Symmetry: Radial symmetry
  • Body Organization: Tissue level of organization (diploblastic)
  • Habitat: Mostly marine, some freshwater
  • Body Structure: Hollow, sac-like body; presence of cnidocytes (stinging cells) for defense and capturing prey
  • Reproduction: Both sexual and asexual (budding in some)

Examples:

  • Jellyfish (e.g., Aurelia)
  • Sea anemones (e.g., Adamsia)
  • Hydra

3. Phylum Platyhelminthes (Flatworms)

Key Characteristics:

  • Symmetry: Bilateral symmetry
  • Body Organization: Organ level of organization (triploblastic)
  • Body Structure: Flat body with no body cavity (acoelomates)
  • Excretion: Flame cells
  • Reproduction: Sexual (hermaphrodites) and asexual (regeneration)

Examples:

  • Planaria
  • Fasciola (Liver fluke)
  • Taenia (Tapeworm)

4. Phylum Nematoda (Roundworms)

Key Characteristics:

  • Symmetry: Bilateral symmetry
  • Body Organization: Organ level of organization (triploblastic)
  • Body Structure: Cylindrical, unsegmented body with a pseudocoelom (body cavity)
  • Excretion: Renette cells
  • Reproduction: Sexual (distinct male and female)

Examples:

  • Ascaris
  • Wuchereria (Filarial worm)
  • Enterobius (Pinworm)

5. Phylum Annelida (Segmented Worms)

Key Characteristics:

  • Symmetry: Bilateral symmetry
  • Body Organization: Organ system level of organization (triploblastic)
  • Body Structure: Segmented body, true coelom (body cavity)
  • Excretion: Nephridia
  • Reproduction: Sexual (hermaphrodites in earthworms)

Examples:

  • Earthworm (e.g., Lumbricus)
  • Leech (e.g., Hirudo)
  • Nereis (Marine polychaete)

6. Phylum Arthropoda (Arthropods)

Key Characteristics:

  • Symmetry: Bilateral symmetry
  • Body Organization: Organ system level of organization
  • Body Structure: Segmented body, exoskeleton made of chitin, jointed appendages
  • Respiration: Gills, trachea, or lungs depending on class
  • Reproduction: Sexual

Examples:

  • Insects (e.g., Housefly, Butterfly)
  • Arachnids (e.g., Spider, Scorpion)
  • Crustaceans (e.g., Crabs, Shrimps)

7. Phylum Mollusca (Mollusks)

Key Characteristics:

  • Symmetry: Bilateral symmetry (except some adults)
  • Body Organization: Organ system level of organization
  • Body Structure: Soft body, usually covered by a calcium carbonate shell
  • Respiration: Gills or lungs
  • Reproduction: Sexual

Examples:

  • Snails (e.g., Pila)
  • Octopus (e.g., Octopus vulgaris)
  • Oysters (e.g., Ostrea)

8. Phylum Echinodermata (Echinoderms)

Key Characteristics:

  • Symmetry: Radial symmetry (in adults), bilateral symmetry (in larvae)
  • Body Organization: Organ system level of organization
  • Body Structure: Spiny skin, water vascular system
  • Reproduction: Asexual (regeneration) and sexual (external fertilization)

Examples:

  • Starfish (e.g., Asterias)
  • Sea urchins (e.g., Strongylocentrotus)
  • Sea cucumbers (e.g., Holothuria)

9. Phylum Chordata (Chordates)

Key Characteristics:

  • Symmetry: Bilateral symmetry
  • Body Organization: Organ system level of organization
  • Key Features:
    • Notochord (at some stage)
    • Dorsal hollow nerve cord
    • Pharyngeal gill slits
    • Post-anal tail

Subgroups of Chordates:

  1. Invertebrate chordates (e.g., Tunicates, Lancelets)
  2. Vertebrates (Animals with a backbone)
    • Classes of Vertebrates:
      • Pisces (Fish)
      • Amphibia (Amphibians)
      • Reptilia (Reptiles)
      • Aves (Birds)
      • Mammalia (Mammals)

MCQs – Animal Kingdom

1. Which phylum includes animals with a true coelom?

a) Nematoda
b) Porifera
c) Annelida
d) Platyhelminthes

Answer: c) Annelida

2. Which of the following animals belongs to Phylum Arthropoda?

a) Earthworm
b) Starfish
c) Spider
d) Snail

Answer: c) Spider

3. The body of animals in Phylum Coelenterata is characterized by:

a) Segmentation
b) Radial symmetry and cnidocytes
c) Presence of notochord
d) Soft body with a shell

Answer: b) Radial symmetry and cnidocytes

4. Which phylum includes the largest number of animal species?

a) Mollusca
b) Arthropoda
c) Chordata
d) Annelida

Answer: b) Arthropoda

5. Which of the following is a feature of Phylum Mollusca?

a) Exoskeleton made of chitin
b) Soft body with a calcium carbonate shell
c) Water vascular system
d) Jointed appendages

Answer: b) Soft body with a calcium carbonate shell

6. In which phylum do animals have a water vascular system for locomotion?

a) Chordata
b) Mollusca
c) Echinodermata
d) Arthropoda

Answer: c) Echinodermata

7. Which of the following phyla includes animals that are bilaterally symmetrical at some stage?

a) Coelenterata
b) Echinodermata
c) Porifera
d) Platyhelminthes

Answer: d) Platyhelminthes

8. The major characteristic feature of Phylum Chordata is the presence of:

a) Notochord
b) Jointed appendages
c) Pharyngeal gill slits
d) Segmentation

Answer: a) Notochord

9. Which of the following animals belongs to the class Mammalia?

a) Frog
b) Shark
c) Tiger
d) Lizard

Answer: c) Tiger

10. Which phylum includes marine animals that possess cnidocytes (stinging cells)?

a) Mollusca
b) Coelenterata
c) Arthropoda
d) Platyhelminthes

Answer: b) Coelenterata