Which layer of the earth is about 85% of iron

the mantle

Explanation:

2885 kilometers thick and is the middle layer of the Earth

the earth's mantle

the mantle is made up of several minerals such as iron, magnesium, silica and oxygen.

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."