Groundwater is the largest available source of freshwater, followed by lakes, rivers, reservoirs and wetlands. Groundwater refers to all subsurface water.
        
                    
             
        
        
        
The vector, which is often a small, circular piece of dna that can exist outside the bacterial chromosome, is known as a plasmid. 
Bacteria and certain other microscopic species contain plasmids, which are tiny circular DNA molecules. Physically distinct from chromosomal DNA, plasmids multiply on their own. They normally contain only a few genes, including some linked to antibiotic resistance, and they can spread from one cell to another. 
Recombinant DNA techniques are used by scientists to splice the genes they want to research into a plasmid. The inserted gene is duplicated along with the plasmid when it duplicates itself. Molecular cloning, the process of creating DNA molecules and introducing them into a host cell, uses plasmid vectors as the means of delivering recombinant DNA into the host cell. 
To know more about plasmids, refer to the following link: 
brainly.com/question/7826558
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Answer:
a.There are three signaling pathway 
1- Reception in which molecule binds to receptor
2- Signal transduction in which activation of intracellular pathway and enzyme occur.
3- Cellular response in which specific response of cell occur according to receptor and ligand.
 b. Three types of receptors are
1- autocrine
2- paracrine
3- endocrine.
Explanation:
autocrine receptors are signaling pathway in which cell releases its molecule and bind to its own cell receptor example cancer cells while paracrine in which ligand binds to other nearby cell receptor and it is used during development  and in endocrine cell target distinct cell and travel through blood stream like hormones functioning.
 
        
                    
             
        
        
        
Cyanobacteria obtain their energy through photosynthesis