Zoology

The exoskeleton of Arthropods is made up of Chitin.

(A) Hyaluronic Acid - Incorrect: This is a component of animal connective tissue, not exoskeletons.

(B) Chitin - Correct: Arthropod exoskeletons consist of chitin, a nitrogen-containing polysaccharide.

(C) Waxes - Incorrect: While waxes may coat the exoskeleton, they're not its structural component.

(D) Cellulose - Incorrect: This is the plant cell wall component, not found in arthropods.

The correct answer is (B) Chitin, the characteristic tough polysaccharide in arthropod cuticles.

Phylum identification based on characteristics:

(A) Coelenterate - Incorrect: While marine and diploblastic, they lack comb plates and show both sexual/asexual reproduction.

(B) Mollusca - Incorrect: These are triploblastic and show bilateral symmetry (except cephalopods).

(C) Arthropoda - Incorrect: Triploblastic with chitinous exoskeleton and jointed appendages.

(D) Ctenophora - Correct: Comb jellies match all characteristics - eight ciliated comb rows, diploblastic, marine, exclusively sexual reproduction with bioluminescence.

The correct answer is (D) Ctenophora, commonly called comb jellies or sea walnuts.