Greenhouse gases arise naturally, and are part of the make-up of our atmosphere. Earths conditions are just right to allow life, including us, to flourish. Part of what makes Earth so amenable is the naturally-arising greenhouse effect, which keeps the planet at a friendly 15 °C (59 °F) on average. But in the last century or so, humans have been interfering with the energy balance of the planet, mainly through the burning of fossil fuels that give off additional carbon dioxide into the air. The level of carbon dioxide in Earth’s atmosphere has been rising consistently for decades and traps extra heat near the surface of the Earth, causing temperatures to rise.
        
                    
             
        
        
        
Tourism can affect the swamp water, if traveled on a boat, with all the oil and stuff that is needed to get the boat running, and over hunting, can slowly kill all the crocodiles that live there affecting the crocodile population! <span />
        
             
        
        
        
Answer:
DNA is duplicated, or copied
Explanation:
Hope this helps
 
        
                    
             
        
        
        
Answer:
Based on this, you know that Sampson is using the whistle as a <u><em>secondary </em></u> reinforcer to train the dolphins.
Explanation:
Secondary Reinforcement can be described as a condition in which  a stimulus initiates a behavior after being previously associated with a primary reinforcer. A secondary reinforcement is a stimulus that satisfies basic survival instinct such as food, drinks, and clothing. 
The same phenomenon was being used by Samson to train his dolphins to perform tasks. The dolphins enjoyed the sound of the whistle because previously that sound was paired to them getting their food. 
 
        
             
        
        
        
The answer u r looking for is- D, Nuclear Envelope. Hope I’ve helped ;)