The alveoli. These little air sacs are found on the end of the bronchioles and are the place where oxygen enters the blood and the carbon dioxide leaves. 
        
             
        
        
        
Answer:
F1: Aa Bb Cc: 4.5 lbs
F2: Too many to list: Between 3 lbs and 6 lbs
Explanation:
F1: Aa Bb Cc, will be the genotypes and will weigh 4.5 lbs, the reason for that is because each capital letter allele adds half a pound to the base weight of 3 lbs.
F2: There are many different genotypes that can be present in the second generation, for example (AA BB CC, AA BB Cc, AA BB cc, etc.) each of which will allow the plant to grow to a certain height. The majority of phenotypes will be 4.5 lbs. There will be one who is AA BB CC, and another one person who has the code, aa bb cc.
 
        
             
        
        
        
Answer is;
The animal population in the environment will increase.
 This is because the grass is the main producer in a habitat. Its plentifulness directly influences that of the consumers up the food web. Increase in grass population means reduced competition for primary consumers and their population will therefore increase. This will also reduce competition for secondary consumers and tertiary consumers up the chain.  
 
        
             
        
        
        
photosystem 2, photosystem 1, pumping hydrogen..., and making NADPH