Answer:
One gram of protein has 4Kcal of calories. Proteins should represent between 10 and 15% of daily energy intake. An adult needs daily 0.8 grams of protein per kilogram of body weight. Children, pregnant women, nursing mothers, athletes, and older adults need a little more protein.
Explanation:
 
        
                    
             
        
        
        
Anything that is considered alive must exhibit ALL 7 characteristics of life. A virus may show some characteristics, but it does not show all, so therefore, its not alive.
        
                    
             
        
        
        
Answer: Pigeon and duck.
Explanation:
From that side of the tree, you can see that the pigeon and the duck are closest together in the tree than the other organisms in the other options.
 
        
                    
             
        
        
        
Well I'm not exactly certain where the teacher is going with this, but an often used example is red blood cells (RBCs) aka: erythrocytes.
RBCs are suspended in blood plasma as they flood through vessels around and around the body, so the osmolarity (amount of small particles that affect osmosis) must remain relatively constant. This is termed "isotonic", meaning the same amount of osmosis-influencing particles that are there inside the RBCs' cytosol, within their plasma membranes. 
If the plasma osmolarity get too high, called hypertonic (as with extra salt particles) then water inside the RBCs will have an osmotic force driving it out of the cells' membranes, to flow where there are more salt particles. This will lead to cell shrinkage (called "crenation").
Counter to that, if the plasma osmolarity gets too low, as due to low plasma salt with excessive water intake (for example from the condition "water intoxication"), then the plasma will be hypotonic with respect to the intracellular cytosol concentration. This can result in water rushing into the RBCs' membranes via osmosis, causing the cells to swell from discs into spheres (balls), or even rupture and burst (a phenomenon called "hemolysis").
HOPE THOSE EXAMPLES HELP!!