The structural unit of compact bone is called an osteon, or sometimes referred to as a Haversian system. Compact bone is made up of many osteons
Answer: Global warming is happening because the greenhouse gases are becoming more thicker which makes more of the suns radiation (heat) stay in the earth; as a result, this is increasing the earth's temperature.
The subject is geography :)
Explanation:
<span>B. A prokaryotic cell does not have nucleus and the other one does. The most defining characteristic of eukaryotic cells is their true nucleus. Prokaryotes lack true nucleus</span> and membrane bound organelles.