The first step of PCR During the first step of a PCR reaction,
A. DNA is heated to allow DNA polymerase to add nucleotides to the growing DNA strands.
B. DNA is heated to break the hydrogen bonds that hold the two strands together
C. DNA is cooled to allow DNA polymerase to add nucleotides to the growing
D. DNA strands DNA is cooled to allow the primers to bind to the DNA strands.
The second step of PCR During the second step of a PCR reaction,
A. DNA is heated to allow DNA polymerase to add nucleotides to the growing DNA strands
B. DNA is heated to break the hydrogen bonds that hold the two strands together
C. DNA is cooled to allow DNA polymerase to add nucleotides to the growing DNA strands.
D. DNA is cooled to allow the primers to bind to the DNA strands Primers

First step:

B. DNA is heated to break the hydrogen bonds that hold the two strands together

Second step:

D. DNA is cooled to allow the primers to bind to the DNA strands Primers

Explanation:

Polymerase chain reaction, or commonly called PCR, is a molecular technique invented by Katy Mullis in the 1980's. It is used to amplify a sequence of DNA template to form several copies.

The process of polymerase chain reaction occurs in three major steps viz;

Step 1: In this step, the DNA template is denatured by heating it to a high temperature. This is done to separate the double stranded molecule into single strands by breaking the hydrogen bonds holding the nucleotides base together.

Step 2: Next, the temperature is reduced or allowed to cook in order for short DNA fragments called PRIMERS to bind to the site on the DNA strands. This step is called ANNEALING.

it should be d) transitional fossils.

they show the gradualism of evolution throughout a period of time

for a different answer set the answer would be because the oxygen in the water had depleted (apex)