1) Fish have a two-chambered heart and one circle of blood circulation.
2) Amphibians have a three-chambered heart and two circles of blood circulation.
3) Partially mixed blood in the heart of amphibians and venous blood in the heart of fish.
4) The second (pulmonary) circle of blood circulation, together with the development of the lungs, provided amphibians with the opportunity to live on land
Remember: The process of learning a person lasts a lifetime. The value of the same knowledge for different people may be different, it is determined by their individual characteristics and needs. Therefore, knowledge is always needed at any age and position.