What was the result of collision between the early earth and others, smaller protoplanets ?

as resources become scarce because of population growth, the growth decreases after few years due to lack of resources and food.

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."