The smallest organized unit of life is a cell
        
             
        
        
        
Answer:
Pepsinogen is produced by chief cells and is activated by hydrochloric acid secreted by parietal cells.
Explanation:
Pepsinogen is a proenzyme produced in the chief cells (that are located in the stomach lining) that, when gets activated, is transformed into pepsin - a peptidase with the function to degrade proteins into amino acids.
The reason why pepsinogen is released inactive is that it would break down all of the cell's proteins because of its proteolytic nature. For this reason, it is released as a proenzyme and gets activated when reaches the acidic environment provided by the hydrochloric acid secreted by the parietal cells, also in the stomach lining.
 
        
                    
             
        
        
        
Answer:
If a whole specie of organisms has to survive, they should must possess the ability to reproduce and adopt to environmental conditions in better way. 
For example: If a disaster occurs or a condition of unfavorable weather occurs, the specie will survive even if only few members remain alive. Because those members will reproduce and regrow the community.
The reason is this that reproduction is not important for the survival of one organism, like organism will still survive even if he do not reproduce, but if a whole specie has to survive and continue, reproduction is most important trait.
Hope it help!
 
        
             
        
        
        
Answer:
Aerobic means with oxygen.
 
        
             
        
        
        
Answer: B. Nuclear transfer!
Explanation: 
Nuclear transfer is the process that DNA goes through to get cloned/copied. The cells that make new forms of DNA create a perfect replica.
Hope this answer helps!