The vertical, bolded line in the middle of this map runs through Greenwich, England. This line is known as: 

The largest component in Earth’s atmosphere is:

A __ provides the map with a directional reference.

The layer of the atmosphere that contains the ozone layer is:

The circumference of the Earth at 33oN is:

To find the solar angle, you must have the latitude and the

__ separates the Earth into Northern and Southern hemispheres

The point at which the earth is farthest from the sun is __

The acidity of sweat contributes to the acid mantle that inhibits bacterial growth in the skin.     

Osteoclasts are derived from this type of cell (be specific) ___________________________.