DNA ends up in the alcohol layer at the end of the extraction procedure primarily because it is less dense than the alcohol used. When we perform DNA extraction, we usually break open the cells to release the DNA and then add alcohol to precipitate it out.
To explain this further, during the extraction process, we mix crushed fruit (like a banana) and a solution that helps to break down the cellular structures. This mixture contains water, sugars, and cellular debris that make it quite dense. When alcohol is added, it does not mix with the water and forms a separate layer on top, due to its lower density.
As the mixture settles, the DNA, being less dense than the alcohol, will rise and form a visible layer between the banana mixture (which is denser) and the alcohol. Thus, the correct answer is b) DNA sinks because it’s less dense than the banana mixture.