Yes, Only bacteria can convert molecular nitrogen, into a form which can be utilized by other living beings such as plants. The nitrogen fixed by the bacteria, by this process, become available to the plants, which uptakes it, for their own growth, and is also accumulated in their seeds. Further, leguminous plants have nitrogen-fixing bacteria associated with them in synergy. They provide the plant with additional nitrogen, and in exchange obtain nutrients from the plant, for their growth and division.
        
             
        
        
        
Answer:
B.sea floor spreading
Explanation:
The creation of new crusts at the middle of the mid- ocean ridges is also sea floor spreading. 
The process of sea floor spreading entails the creation of new crusts at the margin of the oceanic crusts. 
Basaltic materials from the subsurface upwells to the surface. 
They cool and solidifies to form new crusts. The old crust is moved behind and away from the margin. This way, sea floor is formed and it spreads in like manner. 
At this margin sea floor is created and at a convergent margin, it is destroyed.
 
        
             
        
        
        
Answer:
Among vertebrates, external fertilization is most common in amphibians and fish. Invertebrates utilizing external fertilization are mostly benthic, sessile, or both, including animals such as coral, sea anemones, and tube-dwelling polychaetes. Benthic marine plants also use external fertilization to reproduce.
= Fish
Explanation:
 
        
             
        
        
        
Answer:
This was the only treatment options adopted for the Ebola in  1995 in the Democratic Republic of Congo. The assumption was that immune response is generated by the virus in the WBC of the infected individuals. These response produce antibodies. 
A total if 8 patients were transfused with these blood contained antibodies, but one of these died, the remaining 7 patients survived.
The antibodies were believed to  have  multiplied(produced b-cells) to neutralize the Ebola virus(antigens)  and to ensure the survival of the patients
Explanation:
 
        
             
        
        
        
It’s an organ that is part of the circulatory system