NTA Abhyas NEET2020BotanyAnimal KingdomPractice
Choose the correct statements: I. Cartilaginous fish swims continuously due to the presence of an air bladder. II. Osteichthyes have four pairs of gills that are covered by an operculum. III. The notochord is persistent throughout life in Chondrichthyes. IV. Teeth of cartilaginous fishes are modified placoid scales.
Options
- AOnly (I) & (II) are correct
- BOnly (II), (III) & (IV) are correct
- COnly (II) & (IV) are correct
- DAll are correct
Correct answer
B. Only (II), (III) & (IV) are correct
Step-by-step solution
Due to absence of air bladder in cartilaginous fishes, they have to swim constantly to avoid sinking. They have usually five pairs of gill slits which are separate and are without operculum.