SAR uses an active sensor, so it produces its own energy. 

Orthorectification techniques correct imagery so it aligns more closely with the map. 

What are the two types of services?

Why is breathing so important?

In the human urinary system, the kidneys __________ urine.

What is the difference between cellular respiration and organismal respiration?

What determines the ability of a mammal to concentrate its urine?

The first line of defense against body cells infected by viruses is produced by __________.

Animals in which of the following phyla are segmented?

The phylogenetic species concept stresses __________ as the criterion for assigning individuals to the same species.