Answer:  b
Explanation:
An open system is when nutrients and waste are moved through the body   freely through the body cavity, rather than being enclosed in veins. 
 
        
             
        
        
        
It is both biotic and abiotic
        
             
        
        
        
Answer:            The correct option is <span>a long carbon and hydrogen chain and a carboxyl group.
Reason:             Fatty acid is basically consists of two main parts:
a hydrocarbon tail connected with carboxylic group as shown in the figure.</span>
 
        
             
        
        
        
The desert and tundra are alike because they both have limited available water. 
        
                    
             
        
        
        
Answer:
Chromosome are part of DNA cells and threads like structure  which contains the human genetic coded information for the humans . humans have total 46 chromosomes . 
Explanation: