The mammalian breast arose from a sweat gland called:

The nDNA diversity of humans is estimated to be at least:

The human female breast is a composite of mammary glands, fibrous connective tissue, ducts, and:

Why did Charles David Keeling start sampling atmospheric carbon dioxide at Cal Tech?

Henry Wexler of the US Weather Bureau and Roger Revelle of Scripps Institute of Oceanography both wanted Charles David Keeling to launch a program that would continuously measure __________ at remote weather stations around the world (e.g. Mauna Loa (Hawaii) and Little America (Antarctica). 

When did movie theaters begin selling popcorn in the United States?

What mammal is the only one that can digest milk as an adult?

Which variety of corn is the most widely grown in the United States?

The cycling of carbon between the atmosphere and living organisms relies on producers ______ and consumers _____.

What is the primary function of a chloroplast?