Answer:
A dolphin breathes through a single blowhole on the top surface of its head. The blowhole is covered by a muscular flap, which provides a watertight seal.
A dolphin holds its breath while below water.
The dolphin opens its blowhole and begins to exhale just before reaching the surface of the water. To open the blowhole, the dolphin contracts the muscular flap.
Explanation:
The process that keeps the number of chromosomes or chromosome number the same from one generation to the next is mitosis.
Frog's heart<span> has one ventricle, while humans have 2, hence deoxygenated blood from body mixes with the oxygenated blood coming from lungs.
Source: S</span><span>ocratic</span>
I'm pretty sure that it is polarity I hope I am right and good luck, but I am pretty sure it's polarity
