Answer:
24 million years
Explanation:
A: GCACTAAGCATCGATTT 
B: GCACCAGGCACTGGTTC 
There are 6 base pair changes between species A and species B. Since we know the rate of change is 1 base pair every 4 million years, we know 6x 4 million is likely how long ago the species diverged. 6x 4 million = 24 million years
 
        
             
        
        
        
The correct answer is: c. An operon is a region of DNA that codes for a series of functionally related genes under the control of the same promoter.
Operons contain cluster of genes that are transcribed together into mRNA or are not expressed at all. Formed mRNA undergos splicing to create monocistronic mRNAs so that can be translated separately. Operons are more often found in prokaryotic cells but it can appear in eukaryotic cells and in viruses.  
 
        
             
        
        
        
Answer: Macrophages 
Explanation:
Kupffer cells also called as Stellate macrophages are special type of macrophages which are found in liver, which lines the wall of sinusoids.
The main function of these cells is clearing any bacteria and apart from that it also functions by breaking down the hemoglobin molecule.
The globin chains are reused and heme part is broken and degraded down into iron which is also reused.