Answer:
La diferencia entre un iceberg y un glaciar es que el iceberg es la pieza de un glaciar que se desprende (o se rompe) cuando las temperaturas suben. Los glaciares están formados por una gran masa de mezcla de nieve y hielo que cubre el fondo del valle de una cadena montañosa.
Explanation:
Answer:
Oxygen levels stay above 15 percent starting 200 million years ago
Explanation:
Atmospheric oxygen levels are related to the evolution on Earth and changes in geochemical cycles that involve climate variations.
The presence of O
2 and evolution of oxygen gave new opportunities to the life on Earth. Oxygen levels in atmosphere have fluctuated between 15% and 35% of atmospheric volume, since the start of the Cambrian period.
So, form the starting 200 million years ago, oxygen level stay above 15 percent and the correct option is "B".
The identify of the four DNA nucleotides is based on b) covalent bonds.