The base of an adenine molecule is made of ribose sugar molecules 
 
        
             
        
        
        
When growing cultures, the agar is<u> inoculated</u> to separate pathogenic colonies of organisms from colonies of normal flora.
Agar is the medium that is used for growing natural, common flora of microorganisms as the majority of the microorganisms can sustain in the agar medium.
If we want to determine a separate pathogenic colony of organisms in an agar medium then we need to inoculate the agar growth medium so that the pathogenic organism is separated from the normal flora of the microorganism. This technique allows us to filter out the cells that have the pathogenic microorganism in it.
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Answer:
Explanation: by interacting with the excretory system
 
        
             
        
        
        
The statements that describe steps taking place in the nitrogen cycle are 
- Many biotic and abiotic factors play a role in recycling nitrogen ( A )
- Farming practices and chemicals lead to a build-up of nitrates in the soil ( E )
Nitrogen cycle is biochemical process whereby nitrogen is converted to various chemical forms as it passes through the atmosphere, Marine and terrestrial ecosystems .
Nitrogen cycle undergoes four ( 4 ) important processes which are :  
- Fixation
- Ammonification
- Nitrification and 
- Denitrification
Hence we can conclude that The statements that describe steps taking place in the nitrogen cycle are :
Many biotic and abiotic factors play a role in recycling nitrogen and 
Farming practices and chemicals lead to a build-up of nitrates in the soil 
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