Answer:
A secondary pollutant
Explanation:
Pollutants can broadly be classified into two main categories based on their formation or synthesis. 1: Primary pollutants, 2: Secondary pollutants.
1: Primary pollutants
Primary pollutant can be considered as any environmental pollutant that is being directly emitted from a certain source like when we burn coal carbon di oxide is directly emitted into the atmosphere so CO2 is a primary pollutant. 
Similarly sulfur di oxide or SO2 is also a primary pollutant that is emitted by the gas emissions of motor vehicles.
2: Secondary pollutants:
On the other hand, secondary pollutant is something that is not directly emitted on earth as an environmental pollutant but some how it is formed due to a reaction of primary pollutant. 
Such as mentioned in the question that SO2 when oxidized in air in the presence of enzymes and water, it form H2SO4 or acid rain which directly falls on earth and incurs great amount of damage to not only living organisms but also non-living organisms such as marble buildings.
Therefore, acid rain is secondary pollutant. Please see picture for better understanding.
Hope it help!
 
        
             
        
        
        
It’s is heterotroph, hope this helps!
        
             
        
        
        
Answer:
A gene is a stretch of DNA or RNA that determines a certain trait. Genes mutate and can take two or more alternative forms; an allele is one of these forms of a gene. For example, the gene for eye color has several variations (alleles) such as an allele for blue eye color or an allele for brown eyes.
Explanation:
 
        
             
        
        
        
Answer:
Through natural selection, those organisms which have better adaptations to survive in an environment are able to live and pass on their alleles to their offsprings. Hence, any trait which is beneficial to an organism will be favoured by natural selection. 
As tissue pockets is a trait which is required by the shrimps, hence with the passage of time shrimp population having tissue pockets will increase and will be favoured by nature.