Characteristics of Class Chondrichthyes — NEET Biology
📚 Practice ConceptThey are marine animals with streamlined body and have cartilaginous endoskeleton. Mouth is located ventrally. Notochord is persistent throughout life. Gill slits are separate and without operculum (gill cover). The skin is tough, containing minute placoid scales. Teeth are modified placoid scales which are backwardly directed. Their jaws are very powerful. These animals are predaceous. Due to the absence of air bladder, they have to swim constantly to avoid sinking.
Assertion (A): Cartilaginous fishes have adapted their swimming behavior for survival. Reason (R): Constant swimming depends on the absence of air bladder for buoyancy control.
View solution & NCERT explanation
Correct answer: A — If both assertion and reason are true and the reason is the correct explanation of the assertion.
NCERT confirms cartilaginous fishes swim constantly as adaptation (Assertion true). NCERT states “Due to the absence of air bladder, they have to swim constantly to avoid sinking” (Reason true). The Reason explains the dependency - constant swimming behavior depends on lacking the buoyancy control mechanism that other fishes have, explaining WHY this behavior evolved.
What does NCERT say about They are marine animals?
Has this concept appeared in NEET?
Which chapter is this from?
Through deep analysis of NEET and NTA, 88 of 90 questions from the NEET 2026 paper were matched straight from the MedicNEET Biology question bank.
88/90MedicNEET's Biology question bank is built from the same NCERT lines NTA picks repeatedly. Not random MCQs — questions crafted exactly like NTA crafts them.