Primary producers use an energy source (usually sunlight) to build organic molecules.
        
             
        
        
        
Answer:
The correct option is <em>B. Cholesterol is non-polar.</em>
Explanation:
Cholesterol is a non- polar substance and due to this property it is an active part of the cell membrane. Cholesterol molecules help to maintain the stability of a cell. When the temperatures are high, cholesterol stops the cell membrane from crystallization. When the temperatures are low, cholesterol reduces the packaging of molecules of phospholipids. As a result, fluid phase is archived by the cell membrane.  
 
        
             
        
        
        
Answer:
D. the nucleus contains the protons and neutrons which takes up most of the mass of the atom
Explanation:
 
        
                    
             
        
        
        
Answer:
These islands are barrier islands.
Explanation:
Barrier islands are islands in front of the mainland that separate part of the sea from the open sea. They lie parallel to the coast and have an elongated, narrow shape. On the sea side, dunes often shape the surface, on the land side they are flat. They were created by deposits of waves, currents and wind. Their formation requires a shallow coastal fore, a sufficiently large sediment store and a weak to moderate tidal range. 
 
        
             
        
        
        
Answer:
The correct option is <em>A) Carry out DNA cloning of the desired sequence into a plasmid vector and then put that into bacteria and wait for the bacteria to copy the gene every time the cells divide.</em>
Explanation:
The DNA can be easily cloned by the help of vectors like plasmids. Plasmids can be described as an extra-chromosomal ring which is present in bacteria. The plasmid has many multiple cloning sites where the desired DNA can be incorporated. the plasmid with the foreign DNA is then incorporated back into a bacterial cell. As bacterial cells like E.coli divide in a short period of time, many copied of our DNA could be obtained whenever the bacterial cell replicates.