Trees take in carbon dioxide to build their tissues , which releases oxygen for us in the process.
        
                    
             
        
        
        
Explanation:
There's a simple reason why Japanese people can't pronounce R and L correctly.  They don't exist in Japanese.  
Hope this helps :)
 
        
             
        
        
        
A decrease in dissolved oxygen. 
This is because oxygen is a byproduct of photosynthesis. If the plants are in water, some of the oxygen they produce will become dissolved in it. Without those plants, you have less dissolved oxygen. 
        
             
        
        
        
Answer:
To put it simply, the models need to be smaller to fit on the Earth. If, the model was to scale, we'd risk getting crushed.
Explanation: