The respiratory system brings air into the lungs supplying the blood with oxygen. Oxygen is carried throughout the body to the organs and keeps the heart pumping and when the blood circulates back to the lungs the process starts over again.
<span>Mutations sometimes improve the chances of survival for an animal.
But rather rarely. Advantageous mutations do happen, but neutral and harmful mutations are way more common.
</span>
Biological soil crusts<span> are communities of living organisms on the </span>soil<span> surface in arid and semi-arid ecosystems. They are found throughout the world with varying species composition and cover depending on topography, </span>soil<span> characteristics, climate, plant community, microhabitats, and disturbance regimes.</span>
Answer:
fossil fuel doesnt need atmospheric carbon for burning
