Answer:
Changes can occur to physical properties of a substance, but the chemical composition of the substance remains the same.
Answer:
It is the biological concept of species
Explanation:
In 1970 Mayr stated that "species are formed by groups of potentially intercrossing populations that are reproductively isolated from others". The biological concept of species puts emphasis on existence of barriers that limit the gene flow among groups within the same species
Frogs are said to have two lives because they live on land and in water. When they are born, and then as they grow up to live on land.