How long a typical red blood cell (blood, in general at the blood bank) lasts or is good for?

Red blood cells carry oxygen from your lungs to your tissues. They also bring carbon dioxide back to your lungs. Red blood cells make up almost half of your blood. The lifespan of a red blood cell is around 120 days.

c.) polymerase chain reaction

- "unlike the original dna fingerprinting method, dna profiling does not use restriction enzymes to cut the dna. instead it uses the polymerase chain reaction (pcr)? to produce many copies of specific str sequences. pcr is an automated procedure that generates lots of copies of a specific sequence of dna."

hydrogen is a compound or a single element and a element is a pure substence that cannot be separated into simpler subtances

clorine is a compound its a chemical substance that forms when two or more different elements combine

so both hydrogen and clorine are compounds