Hemoglobin is a red protein responsible for transporting oxygen in the blood of vertebrates. Its molecule comprises four subunits, each containing an iron atom bound to a heme group.
A <u>population</u><u> </u>is all of the individuals of one species that live together in one place at one time.

Frequency is the term that describes the number of waves passing a point during a certain period of time, frequency is also measured in Hz (hertz).