Explanation:
Frogs have a three-chambered heart. It consists of two atria and one ventricle. The right atrium receives deoxygenated blood from the body organs. The left atrium receives oxygenated blood from the skin and lungs. Both the atria send the blood to the ventricle. Since there is only one ventricle there is the mixing of both oxygenated blood and deoxygenated blood.