Question

Mark the incorrectly matched pair –

• A. Petromyzon - Body devoid of scales and paired fins
• B. Exocoetus - Heart two chambered with sinus venous
• C. Scoliodon - Operculum present but air bladder is absent
• D. Rana - Cold blooded with $10$ pairs of cranial nerves and mesonephric kidneys

Answer 1

The correct option is C Scoliodon - Operculum present but air bladder is absent

Solution- b

Cyclostomata (Petromyzon) have a sucking and circular mouth without jaws. Their body is devoid of scales and paired fins.
In Chondrichthyes (scoliodon), gill slits are separate and without operculum (gill cover). Also due to the absence of air bladder, they have to swim constantly to avoid sinking.
Osteichthyes (Exocoetus) have two chambered heart (one auricle and one ventricle) with sinus venous.
Amphibian (Rana) is cold blooded with 10 pairs of cranial nerves and mesonephric kidneys.