The changes will occur in an aquatic ecosystem as a result of nutrient loading are: changes in natural flow regimes as a result of water extraction and supply direct modification or destruction of important habitats barriers to the movement of plants and animals. For example within rivers and between rivers and their floodplain effects of poor water quality competition from introduced, <span>exotic animal and plant species. </span>
        
             
        
        
        
A DNA molecule is like a ladder because there are two sides (the sugar-phosphate backbones of the two strands) and rungs (each rung being a pair of complementary bases). Twisted, because the molecule is twined in a coil called a helix - or rather, a double helix because there are two strands.
        
                    
             
        
        
        
Nutrients and energy from the food (as well as water) we eat are absorbed in the intestines.
        
                    
             
        
        
        
I'd say A: tidal waves. B, C, and D don't really seem to fit for me.