Answer:
Nucleic acid would be responsible.
Explanation:
OK. First, there's the heart. Then there's the blood vessels. The arteries. Then the veins. And then there's the capillaries. <span />
Living on land means reptiles can't rely on absorbing oxygen through their skin like amphibians. All reptiles have lungs they use for breathing -- even those who live most of their lives near or in water, such as crocodiles, must surface to breathe. Lungs allow reptiles to venture far away from aquatic environments.