The right answer is "<span>fat soluble are stored in the liver and fatty tissue ...".
Lipids are essentially stored as fatty acids in the cytoplasm of adipocytes. All of these cells form adipose tissue, commonly called "fat".These reserves are much larger in quantity than the reserves in the form of glycogen, in the human body.
"<span>water-soluble vitamins can build to toxic levels ..." is false, hydrosoluble vitamins are rarely toxic, even at high concentrations, and even if they are toxic (which is very rare) is it not due to their circulation in the bloodstream, it is due to their accumulation in cells.</span>
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<span>Organelles are needed for all cells to sustain life. Cell theory states:
-that all living things are made of cells
-all cells camef rom preexisting cells
-and all cells are the basic structure of life.
The function or organelles is that it carries the little organs which are needed for specific functions in the body.</span>
        
                    
             
        
        
        
Answer:
Mutations leading to the better attachement of virus to the host cell would allow the virus to spread the infection and leave more progeny. The reproductive fitness of mutant viruses would allow the mutation to spread. 
Explanation:
1. The organisms with same resource requirement compete with each other. Viruses are not living things but once inside the host cell, they behave like living things. Rapid multiplication of virus overpopulate the host cells.
2. Genetic variations are added to the viral progeny by random errors during replication of the viral genome. These random variations may  impart beneficial trait, harmful feature or remain neutral. If a random mutation in the SARS-CoV2 virus allows it to adhere better to the cells of the respiratory system, the virus would be better able to infect these cells to spread the infection. Once inside the host cells, the mutant virus would leave more progeny. On the other hand, the wild type virus that lack this mutation would  have lesser chances of entering the host cells and may or may not replicate. 
3. The progeny of the mutant virus would compete better with the non mutant ones due to the presence of same mutation. 
4. Differential reproduction and more progeny of the mutant virus would spread the mutation among the virus. 
 
        
             
        
        
        
Viruses are the only thing considered to be a living thing without cells, as they attach themselves to cells to multiply.