Answer:
Passive transport must occur to maintain homeostasis. Active transport must occur to get the needed nutrients in and out of the cell.
Explanation:
 
        
             
        
        
        
Answer:
Natural selection
Explanation:
Natural selection occurs when one allele (or combination of alleles of different genes) makes an organism more or less fit, that it is able to survive and reproduce in a given environment. If an allele reduces fitness, its frequency will tend to drop from one generation to the next.
 
        
             
        
        
        
The Sun is the main cause for our weather, and different season (in different areas where you live it depends on how hot or cold it is also caused by the sun)
Most seasons, like in summer it's hot Also caused by the sun, in winter it snows because the sun is in a different location.
        
             
        
        
        
<span>The deposition of heavy sediment can significantly diminish the water quality and aquatic habitat.  The sentiment in the water can reduce the sunlight that reaches the floor of the waterway, affecting animal and plant life. For example, photosynthesis may be less effective due to the decreased sunlight and the gills of fish may get clogged from the sediment.</span>