Answer:
Smaller the size of the DNA fragment, farther it moves during electrophoresis. The sketch of the position of the fragments has been drawn in the figure below.
Explanation:
As we know DNA is a negatively charged molecule. So during electrophoresis the fragments move towards the positive electrode because opposite charges attract each other.
Different fragment move different distances according to their size during the electrophoresis. Smallest segment travels the largest distance in the gel medium while the largest one travels least distance.
In the question there are four DNA fragments with base pairs 4000, 2500, 2000 and 400 so the smallest segment with 400bp will be farthest from the starting point and the largest fragment with 4000bp will travel least distance in the gel medium. Their respective positions are shown in the figure below. The starting point is near the negative electrode.
