Leading and lagging DNA strands exist at a replication fork because .A. the DNA polymerase can add new nucleotides onto either the 3' end or the 5' end B. the two strands of DNA are antiparallel, and DNA polymerase can only add new nucleotides onto a 5' end C. the two strands of DNA are parallel and DNA polymerase can only add new nucleotides onto a 3' D. end the two strands of DNA can be either parallel or antiparallel the two strands of DNA are antiparallel, and DNA polymerase can only add new nucleotides onto a 3' end

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

primary succession begins with a bare rock and ends with a forest secondary succession begins after a natural disaster where there is a temporary setback after a forest fire or local destruction, but the surrounding area can fill in

genetic variation can be caused by mutation (which can create entirely new alleles in a population), random mating, random fertilization, and recombination between homologous chromosomes during meiosis (which reshuffles alleles within an organism's offspring).

that is wrong, its not thymus.