if I were to add salt to water and freeze it, the water would take longer to freeze or is it that it needs a colder temperature to freeze? If i wanted to do this experiment how would I test it, based on time or changing the temperature?

well because of the salt in the water that is why it takes longer to freeze.

Explanation:

To test for it, use two containers, one which contains only water and the second should be one with salt solution.

then experiment the time each take to freeze.

hope it helps .

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."