The molecules in the sugar move from an area of higher concentration (sugar cube) to an area of lower concentration in the water.
That is exactly what diffusion is: the net movement of molecules or atoms driven by a gradient , which means that it doesn’t requires energy.
 
        
             
        
        
        
Gravity can be such a tricky subject to talk about I wish I could answer this I need to study more
        
                    
             
        
        
        
Answer:
Embedded in the lipid bilayer are large proteins, many of which transport ions and water-soluble molecules across the membrane. Some proteins in the plasma membrane form open pores, called membrane channels, which allow the free diffusion of ions into and out of the cell.
 
        
             
        
        
        
Meteorology is the science of the weather. The weather person on the TV is a meteorologist. 
Some of them quite liked meteorology, but others only tolerated it as it is not an exact science
 
        
             
        
        
        
So abiotic means nonliving, so the only abiotic option is B. the gravel on the bottom of the aquarium.