The structural polysaccharide that forms the exoskeleton of arthropods is: MCQ with Answer and Explanation

Explanation:
Scoliodon is a cartilaginous fish (Chondrichthyes), possessing a cartilaginous endoskeleton, placoid scales, and ventral mouth. Rohu and Catla are bony fishes (Osteichthyes). Hippocampus is also a bony fish. Chondrichthyes include sharks, rays, and skates. They lack an air bladder and have to swim constantly to avoid sinking.

Explanation:
Glycogen is a highly branched polysaccharide of glucose, the storage form in animals, found mainly in the liver and skeletal muscles. Starch is the plant equivalent. Cellulose is structural in plants, sucrose is a disaccharide. Glycogen can be rapidly mobilized to maintain blood glucose.

Explanation:
The appendix is considered vestigial (reduced and non-essential), but recent studies suggest it may have a minor immune function or serve as a reservoir for gut bacteria. So R is not entirely true (it may have a function). Thus, A is true but R is false (no function is an oversimplification).