Answer:
(1) by increasing carbon dioxide and decreases oxygen
 
        
             
        
        
        
D.hot air rising and cooler air falling. A is example of radiation or conduction. B is example of radiation. C is example of conduction. D is example of convection
 
        
                    
             
        
        
        
In a cornfield, only one plant species has dominated the area, that is the corn plant. While in a natural meadow, multiple species of plants occurs of different species. The presence of the different types of plants in the meadow will interact more number of insects in it as compared to the corn field. This will lead to more interactions among the different species in a natural meadow. The greater biodiversity of the natural meadow than the cornfield will support it better. 
In case of any natural disaster, or a pest attack, all the plants will be killed in a corn field and so will the insects dependent on them, but in a natural meadow, if one plant species is killed by a natural disaster, other will still be alive. Hence, the ability to survive is greater in natural meadow.
 
        
             
        
        
        
Answer:
D) In DNA, adenine, thymine, guanine, and cytosine join together and carry all of the genetic information. RNA is made from adenine, uracil, cytosine, and guanine and is used to make proteins.