Well, historical events is a broad subject, but there are specific events that could contribute to how we value and think about the environment. for example, events as broad as wars or as specific as the gulf of mexico oil spill contributes to the way we treat our environment. and, as a society, we know about global warming and pollution, and if we analyze mistakes we made in our past through events, it could be possible that it benefits our relationship and care for the environment in the future.
        
             
        
        
        
Answer:
Like questions 16-20? there aren't any questions to be answered.
Explanation:
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Answer to your question what nitrogen base sequence is paired with CATCGA is 
O GTAGCT
        
             
        
        
        
Answer: The only reaction performed by chloroplast through its chlorophyll is photosyntesis. Therefore the chemical formular is below.
    C02         +          H20           →                   C6H1206    +       O2+           H20.
(carbondioxide) +    (Water)     Chlorophyll      (glucose)  +(oxygen)+     (water) 
                                                        and                                                                                            
                                                    enzymes .                    
This is the single reaction of the process of photosynthesis.However two interconnected reactions are involved light dependent stage and light independent stage.
The first reaction takes place in presence of sunlight, and it is called Photolysis of water.it is the spiting of water to H+, electrons and Oxygen. This is  the source of oxygen seen above. 
              4 H20→ 4H+ + 4e- + 02.
The light independent stage; the hydrogen ion from the photolysis is transfer to the light independent stage to reduce the C02 to produce glucose.In the first equation seen above.
Since chloroplast performs photosynthesis through action of its chlorophyll, The above reaction describes the chemical formula.
B.
The cell wall  of plants is made up of the middle lamella, the primary cell wall and the secondary cell wall .
<u>Cellulose</u><u> a complex carbohydrate is the major components</u>. It contains,  monomers of  glucose in small units  linked to one another by bonds.
C
Vacuole helps in plant turgidity needed for uprightness. when filled with water provides  turgor pressure increases as the cell membrane pushes against the cell wall. The resulted turgidity  helps the plants  to maintain resistance to external pressure and therefore resist the effects of gravity.