Answer:
they need a high ‘surface to volume’ ratio, which is good for exchanging materials between the inside and outside of cells. But this is probably not really the size-limiting reason, since cells vary enormously in size and surface area to volume ratios.
Explanation:
Answer:
Real dinosaurs can not be studied because they died out many years ago. so this is how we are learning about the past
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".
