Answer:

(i) The coelom is the fluid-filled body cavity present between the alimentary canal and the body wall.” The true coelom has a mesodermal origin. It is lined by mesoderm. The peritoneal cavity present in the abdomen and similar spaces around other organs such as lungs, heart are parts of the coelom.

(ii) It is found in animals and serves as a basis of classification for the animal kingdom. The presence of a body cavity that is lined by mesoderm is referred to as coelom, the presence of patches of mesoderm in the body cavity is termed pseudocoelom

(iii) The nephridium is a pair of invertebrate kidneys that operate similarly to vertebrate kidneys. In earthworms, nephridia are responsible for maintaining osmoregulation.

(iv) Chitin contributes to the rigidity of the insect cuticle and serves as an attachment matrix for other cuticular proteins. Deficiency of chitin results in abnormal embryos, cuticular structural defects and growth arrest.

(v) The mantle is the mostly-solid bulk of Earth's interior. The mantle lies between Earth's dense, super-heated core and its thin outer layer, the crust.

(vi) 1 : any of the openings or clefts between the gill arches in vertebrates that breathe by gills through which water taken in at the mouth passes to the exterior and so bathes the gills. 2 : any of the rudimentary grooves in the neck region of the embryos of air-breathing vertebrates that correspond to the gill slits.

(vii) Definition of notochord

: a longitudinal flexible rod of cells that in the lowest chordates (such as a lancelet or a lamprey) and in the embryos of the higher vertebrates forms the supporting axis of the body.

(viii) The cranium—the part of the skull that encloses the brain—is sometimes called the braincase, but its intimate relation to the sense organs for sight, sound, smell, and taste and to other structures makes such a designation somewhat misleading.

(ix) The operculum is a series of bones found in bony fish and chimaeras that serves as a facial support structure and a protective covering for the gills; it is also used for respiration and feeding

(x) Cycloid scales are round and flexible structures which are present on the surface of bony fishes. Cycloid scales have an outer layer of calcium and an inner layer made of connective tissues. Cycloid scales are the inner layer of ganoid scales. Example: Trout, Herring, Carp, etc.

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Answer:

Coelom. (ii) Pseudoceolom. (iii) Nephridia. (iv) Chitinous cuticle. (v) Mantle. (vi) Gill slits. (vii) Notochord. (viii) Cranium. (ix) Operculum. (x) Cycloid, Ctenoid, Ganoid scales. [Only correct answer needed & will be marked as brainliest

Explanation:

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