Grade 11 : Biology - Animal Kingdom (Set 2)

Explanation: Sponges are multicellular animals exhibiting loose cell aggregates. Thus, they exhibit the cellular level of organization.

Explanation: Any plane passing through the central axis of the body divides the organism into two identical halves in radial symmetry, as seen in cnidarians and ctenophores.

Explanation: Diploblastic animals possess two embryonic germ layers (ectoderm and endoderm) with an intervening undifferentiated mesoglea.

Explanation: In Aschelminthes, the body cavity is not lined by mesoderm; instead, mesoderm is present as scattered pouches between ectoderm and endoderm, forming a pseudocoelom.

Explanation: Annelids display metameric segmentation where the body is externally and internally divided into segments with serial repetition of at least some organs.

Explanation: Porifera (sponges) possess a water canal system where water enters through ostia into the spongocoel and exits through the osculum.

Explanation: Choanocytes (or collar cells) line the interior cavity (spongocoel) and canals, driving water current in sponges.

Explanation: Cnidoblasts (or cnidocytes) contain stinging capsules (nematocysts) used for prey capture, offense, defense, and anchorage.

Explanation: Ctenophores (commonly called comb jellies) are exclusively marine and prominently exhibit bioluminescence.

Explanation: Specialized cells called flame cells help in osmoregulation and excretion in flatworms (Platyhelminthes).

Explanation: Aschelminthes are called roundworms because the body of these animals is circular in cross-section.

Explanation: Annelids possess segmentally arranged coiled structures called nephridia that help in osmoregulation and excretion.

Explanation: Arthropoda is the largest phylum of animals, characterized by jointed appendages and a chitinous exoskeleton.

Explanation: The mouth of molluscs contains a file-like rasping organ used for feeding called the radula.

Explanation: Echinoderms possess a unique water vascular system that assists in locomotion, food capture, and respiration.

Explanation: Hemichordates have a simple body layout divided into proboscis, collar, and trunk, with excretion carried out by the proboscis gland.

Explanation: Class Cyclostomata comprises jawless vertebrates with a sucking and circular mouth; all living members are ectoparasites on some fishes.

Explanation: Chondrichthyes (cartilaginous fishes) have a cartilaginous endoskeleton, ventrally located mouth, and gill slits lacking an operculum (gill cover).

Explanation: Amphibians can live in aquatic as well as terrestrial habitats, possess moist skin without scales, and have a 3-chambered heart (2 atria and 1 ventricle).

Explanation: Birds (Class Aves) feature endoskeletons fully ossified with long bones that are hollow (pneumatic) to reduce body weight for flight.