Answer:
They fall from the clouds as ice crystals.
They form around particles in the atmosphere.
They form when water vapor is converted directly to ice crystals.
Explanation:
 
        
             
        
        
        
It proves that living organisms MUST come from other living organisms, an egg couldn't magically appear in a pile of chicken seed, a hen would have had to lay the egg first, just as a nucleoulus makes ribosomes so the cell can have proteins, the proteins don't just materialize within the organism.
        
                    
             
        
        
        
Genetic drift scientific explanarions are based on empirical data and evidence
        
             
        
        
        
Answer: The reason why stem cell research is a big field in biology or even the world is because stem cells might be able to treat degenerative conditions as well as answering questions about human development.
 
        
                    
             
        
        
        
Cell walls are rigid which gives plants their shape. Animals have only cell membranes which allows animals to be flexible as animals are moving organisms. Plants, on the other hand, are sturdy and upright and are sessile organisms. Cell walls allow plants to grow upright as high as their maximum height and to be sturdy enough to survive harsh environments.