Although humans produce only 400 olfactory receptor proteins, we are able to discriminate possibly 1 trillion odors because:

Which of the following is most important in making the typical seed more resistant to adverse conditions than the typical spore? a) a different type of sporopollenin b) an internal reservoir of liquid water c) integument(s) d) ability to be dispersed e) waxy cuticle

What is the main function of the central vacuole in a plant cell? a. absorbs energy from the sun to produce food b. holds water and maintains turgor pressure c. breaks down molecules to release energy d. contains the cell's genetic material

What is any method of measuring the age of an object or event in years, such as using atomic half-life?