54. Amphibians are cold-blooded animals, meaning they do not have a constant body temperature but instead take on the temperature of their environment. They have moist, scaleless skin that absorbs water and oxygen, but that also makes them vulnerable to dehydration (loss of bodily fluids).
55. The first and foremost characteristic of the reptiles is that are cold blooded. They are able to regulate their inner body temperature to the temperature of the environment. They have scaly skins but absence of hair or fur. The scales of the reptiles develop as a surface cells filled with Keratin.
56. Characteristics of Birds. Birds are endothermic and, because they fly, they require large amounts of energy, necessitating a high metabolic rate. As with mammals, which are also endothermic, birds have an insulating covering that keeps heat in the body: feathers.
57. Mammary Glands.
Undercoat and Guard Hair.
Jaw and Ear Bones.
Four-Chambered Heart and Diaphragm.
Complex Brain Functions.
I had this question on one of my lessons the answer is 15.
From molecule, cells, tissue,organ, organ system,organism
And from organism to the population, community, ecosystem, and biosphere :)
The male structure, called the testes
