Where is the centromere located on the chromosome, and what is its role? 1. It is not exactly at the center, and it always makes the p-arm longer than the q-arm.
2. It is exactly at the center and it is responsible for making the q-arm longer than the p-arm.
3. It is not exactly at center, and it attaches to spindle fibers during cell division.
4. It is exactly at the center, and it attaches to spindle fibers during cell division.

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