Answer: ozone concentration
Explanation: The Dobson Unit is the most common unit for measuring ozone concentration. Becuse ozone concentration is hard to measure they use The Dobson Unit.
 
        
                    
             
        
        
        
Answer;
Insulin and the growth hormone
The hormones that are involved in building and maintaining healthy bone tissues are Insulin and growth hormone
Explanation;
Insulin has some anabolic properties for bone. It is uncertain whether insulin stimulates bone directly or indirectly by increasing muscle work and thus skeletal loading. 
Growth hormone is a peptide hormone secreted from the pituitary gland under the control of hypothalamus. It directly and through IGF-I stimulates osteoblast proliferation and activity, promoting bone formation. Additionally it stimulates osteoclast differentiation and activity,promoting bone resorption. 
        
             
        
        
        
Answer:
It is the varying chemical structure and properties of the R-group that make the amino acids different from one another. About 9 amino acids have non-polar R-groups and are relatively hydrophobic. Another 6 amino acids have strongly polar R-groups which readily attract water molecules.
 
        
                    
             
        
        
        
Answer:
c. the gravitational forces due to the sun and the moon cancel each other's effect
Explanation:
The two diagrams represent Neap tides. Neap tides occur when the Sun, the Moon and the Earth are aligned at right angles. Moderate tides are formed because the bulge due to gravitational pull of the Sun cancels the bulge due to moon. The difference between the high tides and the low tides is the smallest.