Answer: B 
Explanation:
Ammonia is so toxic that it can be transported and excreted only in large volumes of very dilute solution. As a result most terrestrial animals simply don't have access to sufficient water to routine excrete ammonia. 
The main advantage of urea is its very low toxicity. Animals can transport urea in the circulatory system and store it safely in high concentrations. Also much less water is loss when a given quantity of nitrogen is excreted in a concentrated solution of urea than would be in a dilute solution of ammonia.
 
        
             
        
        
        
Answer: creates genetically identical offspring,  organism doesn’t have to waste energy to find a mate organism, requires the contribution of a single parent.
Explanation: While asexual reproduction only involves one organism, sexual reproduction requires both a male and a female. 
Some plants and unicellular organisms reproduce asexually. Most mammals and fish use sexual reproduction.
Asexual Reproduction                   Sexual Reproduction
Two or more                                     One or more
 
        
             
        
        
        
Answer:12.
Containing two complete sets of chromosomes, one from each parent.
Explanation:   Once mitosis is complete, the cell has two groups of 46 chromosomes, each enclosed with their own nuclear membrane. The cell then splits in two by a process called cytokinesis, creating two clones of the original cell, each with 46 monovalent chromosomes.
 
        
                    
             
        
        
        
Answer:
DNA replication is the process in which the DNA is copied and it occurs during synthesis phase of the eukaryotic cell cycle. It begins with an enzyme breaking the bonds between complementary bases in DNA which exposes the bases inside  the molecules so they can be read by another enzyme and used to build two new DNA strands with complementary bases.
Explanation:
The original strand is: TAGCGTT
                                       ATCGCAA
The Mutated strand is: TGGCGTT
                                        ATCGCAA
<em>The replicated strand is: GAATCAC</em>
<em>                                           CTTAGTG</em>