The reason why at the equator, there are no summers or winters, only wet and dry seasons is : Because at the equator the daytime, night time, temperature and sunlight are moderate. 
<h3>Meaning of equator</h3>
An equator can be defined as an imaginary line that runs from west to east thereby dividing the earth into two equal part.
The equator divides the earth into the northern and southern hemispheres. because the equator is at the middle every thing that is experienced there is moderate, unlike the those at the polar region.
In conclusion, The reason why at the equator, there are no summers or winters, only wet and dry seasons is Because at the equator is at the middle and therefore the daytime, night time, temperature and sunlight are moderate. 
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Answer:
nitrogen fixation.
Explanation:
Nitrogen fixation is the process by which the combination of molecular nitrogen oxygen or hydrogen is given to give oxides or ammonium that can be incorporated into the biosphere. Molecular nitrogen, which is the majority component of the atmosphere, is inert and not directly usable by most living beings.
 
        
             
        
        
        
Answer:energy in the form of heat and matter (nutrients, solids, dissolved substances, and gases) 
Explanation:
 
        
             
        
        
        
Answer: To eliminate bacteria that failed to take in the plasmid.
Explanation: 
Research shows that plasmid DNA is only taken in by small percentage of bacteria in a large population.
Therefore, the need of growing transformed bacteria in the presence of ampicillin is very important. The main reason of this process is to kill off or eliminate bacteria that have failed to take in the plasmid, due to their possession of recombinant DNA plasmid pARA-R (an ampicillin resistance gene), that allows them to survive. 
However, after completion of the aforementioned procedure, the bacteria that have been transformed will be able to take in the plasmid.