The answer is letter A.
<span>Organelles and other cellular material are held within a cell by a cellular membrane. These membranes are what consist of a cell's exterior.
</span>
<span>Thank you for posting your question. I hope you found what you were after. Please feel free to ask me more.</span>
 
        
        
        
Answer:
Nitrogen is the most commonly limiting nutrient in plants. Legumes use nitrogen fixing bacteria, specifically symbiotic rhizobia bacteria, within their root nodules to counter the limitation. Rhizobia bacteria convert nitrogen gas (N2) to ammonia (NH3) in a process called nitrogen fixation.
 
        
             
        
        
        
In order to produce an effective immune response within the body, the person must be injected with a dosage of a virus or bacteria, and for it to be allowed to grow in the person, which replicates just enough to stimulate a response from the immune system.
        
             
        
        
        
Answer:
A
Explanation:
<em>The correct option would be </em><em>A.</em>
<u>The presence of ammonia in the atmosphere of primitive earth provided the nitrogen found in the amine groups of amino acid and the nitrogenous bases in DNA. This has been proven through the simulation experiment of the primitive earth's atmosphere by Stanley Miller and Harold Urey.</u>
The water in the primitive atmosphere was formed from the condensation of water vapour from volcanoes that were characterics of the earth's environment while oxygen in itself is not needed for photosynthesis but a by-product of it. 
 
        
             
        
        
        
Cellular resperation releases ATP energy by breaking down the bonds in glucose in the oxygen, energy is produced in order to add a phosphate group to ADP to form <span>ATP.</span>