What would be the first step in using pcr to copy a gene?
a. dna polymerase adds nucleotides to separate strands.
b. various strands of dna are allowed to cool.
c. dna is heated to seperate stands.
d. copied strands are used as templates to make more copies.

The correct answer is C.

During the first step of PCR, called denaturation, the tube containing the sample of DNA is heated to more than 90 degrees Celsius (194 degrees Fahrenheit) which separates the double-stranded DNA into two separate strands. The high temperature  breaks the relatively weak bonds between the nucleotides that form DNA.

PCR stands for Polymerase Chain  Reaction. It is an efficient and cost effective way to copy or amplify small segments of DNA or RNA, now in wide use.

answer: - few nutrients

high pressure

low temperatures

explanation: 1. few nutrients:   open-ocean zone is located way far from the land, which is the main source of the essential nutrients.2. high pressure: pressure increases by 1 atmosphere for every 10 meters increase in depth.3. ample sunlight: a large fraction of the sunlight is reflected back to the atmosphere from the sea surface. 4. varying salinity: below the thermocline, the water is isolated from the atmosphere so the salinity remains stable over the year.5. low temperatures:   the temperature of open-ocean zone ranges from a low of -2°c to an average of 17°c