The opening scene accomplishes the tasks of informative exposition of the play, i. e., it introduces the important characters, elements of the plot and general atmosphere of the play. The foundations of the two major stories - the Bond Story and the Caskets Story are firmly laid in this scene.
Bassanio is the main link between the main plot and sub-plots. Besides, it dwells on the themes of friendship, fidelity, pretence and display of wealth.
In Bassanio's need for money and Antonio's assurance that he can borrow money in his name, originates the main plot of the play,i. e., the Bond Story.
Bassanio is also the hero of the other main plot, the Caskets Story. He wants money from Antonio to visit Belmont and take up the 'Lottery of Caskets' and win Portia.