Four
Explanation:
The hemoglobin molecule gives four binding sites for oxygen molecules: the iron atoms in the four heme groups. so... each Hb tetramer can bind four oxygen molecules
The two most populated cities in Africa are Lagos in Nigeria and Cairo in Egypt. Lagos has a total population of 21 million, whereas Cairo has 20.4 million residents.
Answer:
The universal origin story known as the Big Bang postulates that, 13.7 billion years ago, our universe emerged from a singularity — a point of infinite density and gravity — and that before this event, space and time did not exist (which means the Big Bang took place at no place and no time).
Explanation:
Answer:
c. (the moon revolves around the Earth throughout the day)
Explanation: