Agene pool consists of all the genes within a

"A gene pool consists of all genes, including all the different alleles that are present in a population. Number of times an allele occurs in a gene pool compared with the number of times other alleles occur. In genetic terms, evolution is any change in the relative frequency of alleles in a population."

population

Explanation:

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