Definition: All the individuals of a species that live together in one place at the same time Example: this of humans in the United States in 2005 is around 275,000,000

Population

Explanation:

A population is a group of individuals of the same specie that lives together in one place at the same time.

Individuals in a particular population must be able to interbreed and produce viable offspring.

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