It is important to note that the graph has 0 solar intensity for a long part of the day; around 16 hours. Only from 8 to 16 hours do we have significant sunlight.
This means that the length of day is very short during this time of the year;
The length of the day changes throughout they year; day is equal to night (12 hours each) during the solstices on March 21 and September 23 but during summer day is longer than night in the northern hemisphere; during winter it is smaller. THe smallest daylength is at December 21st (in the northern Hemisphere). This phenomenon is due to the tilt of the axis of the earth.
The correct answer is December 21; (if we talked about a place in the southern hemisphere, the answer would be March 21).
        
             
        
        
        
It's a way of protecting the trees, and making sure they survive the winter and beyond. Leaves die during the winter months. If those dead leaves stayed on the trees, and new ones wouldn't grow in their place, the tree would have no way of making food for themselves. 
Hope it helps. ☺
 
        
             
        
        
        
Urine is stored in the Bladder before it leaves the body.
        
             
        
        
        
It depends upon the protein and also where the deletion of the single amino acid has occurred. Does ur alter or disrupt an important fundamental function or aspect of the protein such as the capability of substrates to bind to the active site, or is near a region that is primarily for developing the additional structure of the protein and is not as important. In most cases, a single amino acid change will not cause the protein to lose its complete function of be denatured.