Question

Heart of rat differs from that of frog by the absence of

• A. Left atrium
• B. Right atrium
• C. Sinus venosus
• D. Pericardium

Answer 1

The correct option is C Sinus venosus

• The structure of the rat heart is almost identical to that of humans.
• There are four chambers in the heart, two above as right atrium and left atrium and two ventricles as left ventricle and right ventricle.
• The pericardium is the double-walled sac that surrounds the heart and is present in the rat as well as in frogs.
• However, the rat does not possess sinus venous. Sinus venous is a large quadrangular cavity that precedes the atrium on the venous side of the heart of the frog (chordates).

So, the correct answer is option C.