Answer:
Acid rain is caused by a chemical reaction that begins when compounds like sulfur dioxide and nitrogen oxides are released into the air. These substances can rise very high into the atmosphere, where they mix and react with water, oxygen, and other chemicals to form more acidic pollutants, known as acid rain.
 
        
             
        
        
        
Answer:
The correct answer will be option-formation of heterochromatin
Explanation:
Methylation of DNA is the epigenetic mechanism which controls the expression of a gene by adding a methyl group to the cytosine bases in eukaryotic DNA.
The methylation of DNA converts the cytosine residues to the  5-methylcytosine catalysed by DNA methyltransferase enzyme. This results in the silencing of the gene and transcription get switched off.
Studies have shown that DNA methylation is involved in the formation and maintenance of the heterochromatin structure which is the condensed form of the chromatin in which transcription is switched off.
Thus, the formation of heterochromatin is the correct answer.
 
        
             
        
        
        
The instrument of choice would be the the clam shell sampler, which is also know as a grab sampler. Another instrument they use is the piston corer which is an open tube on a cable that gets dropped from a ship. 
        
             
        
        
        
Answer:
Bones are organs composed of hard living tissue providing structural support to the body – it's scaffolding. It is a hard matrix of calcium salts deposited around protein fibers. Minerals make bone rigid and proteins (collagen) provide strength and elasticity. ... The outer layer of bone is called Cortical bone.
 
        
                    
             
        
        
        
It is not possible for two species with the same niche to coexist. one species will eventually drive the other into extinction