The partial pressure of oxygen in the alveoli is:

Comparative advantage is the ability of a country, individual, or entity to produce a particular good or service at a lower opportunity cost than another country, individual, or entity. 

The population of ____ has the highest percentage of elderly people.

Which traits below can increase the risk of a species becoming extinct?

The exchange of gases between blood and tissue cells is known as:

The process of logging that removes all of the trees from an area is called ____.

____ is characterized by permafrost.

Pollutant levels in cities are ____.

Succulent plants are most likely to be found in ____.

Maslow’s Hierarchy of Needs show that people act to fulfill 5 needs; Physiological, safety, social, esteem, and self-actualization.