Two classes of vertebrates(aves and mammals) are endothermic. what is meant by this term?

Zoologically, when something is endothermic, it just means that the creature absorbs heat around them. Humans are a great example of endothermic animals. Our bodies stay roughly about 98.6°F, or 37°C. For our bodily functions to occur normally, our temperature cannot drop below a certain point or raise above a certain point, we will actually die. We are dependent on our own closed, self-regulating heat system. However, for perspective, ectothermic animals such as reptiles are dependent on external energy sources, like heating lamps and the sun, for their bodies to stay functional.

Hope I could help!

Mutations are changes in the dna