Answer:
Explanation 
the two basic difference between RNA and DNA are 
RNA is single stranded while DNA is double stranded 
RNA contain uracil and DNA contain thymine
 
        
                    
             
        
        
        
<u>Answer:</u>
- few nutrients
- high pressure
- low temperatures
<u>Explanation:</u>
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.
 
        
                    
             
        
        
        
Answer:
D) Density of air and humidity levels
Explanation: