A polysaccharide obtained from seaweed that is used in gel electrophoresis is

• A. Agar
• B. Starch
• C. Agarose
• D. Cellulose

Answer: (C)

In gel electrophoresis, the gel medium comes from a seaweed-derived polysaccharide that forms a porous, inert matrix to separate molecules by size. That substance is agarose, produced from agar found in red seaweed. By adjusting the gel concentration, the pore size changes, so smaller DNA fragments move more quickly than larger ones, giving a clear size-based separation. Agarose is preferred because it creates a uniform, easy-to-handle gel that doesn’t interact with nucleic acids. Other seaweed-derived or plant polysaccharides like agar (less purified), starch, or cellulose don’t form the same consistent gel suitable for accurate DNA separation. So, the correct substance is agarose.