Answer:
Explanation:
The Earth's axis is titlted so this means that it is pointing to one side of the Sun as it orbits it over a year-long period.
 
        
             
        
        
        
External skeleton is the correct answer. Hope this helps out !
        
                    
             
        
        
        
Answer:
Option (a) and (d).
Explanation:
The breaks in DNA molecule may occur due to replication error and oxidizing agent. The double-stranded breaks in DNA can be corrected by Homologous end joining and non homologous end joining.
Homologous end joining is used to repair the DNA present in G2 nad S phases of the cell cycle. The homologous sequences of DNA is used to repair the DNA. Non homologous end joining occurs in the cell present at G0 and G1 phase of the cell cycle. The DNA broken ends are juxtaposed and later rejoin together by DNA ligase.
Thus, the correct answer is option (a) and (d).
 
        
             
        
        
        
Scientists often perform experiments to check and recheck their work.  They also redo these experiments to ensure correct results.
 
        
             
        
        
        
When Linnaeus developed his system of classification, there were only two kingdoms, Plants and Animals. But the use of the microscope led to the discovery of new organisms and the identification of differences in cells. A two-kingdom system was no longer useful. Today the system of classification includes six kingdoms.