How does Act 1, Scene 2 display a mood of melancholy, anxiety, and suspense in The Merchant of Venice?

As Act I Scene 2 opens, Portia sighs and in the lugubrious tones of melancholy tells her waiting woman Nerissa that she is weary of the world because she feels that her life is still controlled by her father even though he is no longer alive. This melancholy has been caused because her father has arranged that suitors for Portia must go through a lottery involving three chests--one gold, one silver, and one lead. The man...

As Act I Scene 2 opens, Portia sighs and in the lugubrious tones of melancholy tells her waiting woman Nerissa that she is weary of the world because she feels that her life is still controlled by her father even though he is no longer alive.
This melancholy has been caused because her father has arranged that suitors for Portia must go through a lottery involving three chests--one gold, one silver, and one lead. The man who selects the correct chest gets to marry Portia. Portia bemoans,

O me, the word “choose!” I may neither choose whom I would nor refuse whom I dislike—so is the will of a living daughter curbed by the will of a dead father. Is it not hard, Nerissa, that I cannot choose one nor refuse none? (1.2.22-25)

Nerissa attempts to console her by saying that Portia's father has arranged his lottery so that only a man who would be capable of truly loving her should make the correct choice. But, Portia expresses her anxiety over her potential husband as she evaluates the suitors who have come by so far. Then she tells Nerissa:

If I live to be as old as Sibylla, I will die as chaste as Diana unless I be obtained by the manner of my father’s will (1.2.95-96)

Since many potential suitors have come and gone, Portia is beginning to worry if she ever will find a suitor that she likes. Then, Nerissa reminds Portia of a certain Venetian scholar and soldier, and Portia exclaims, "Yes, yes, it was Bassanio." Nerissa tells Portia that Bassanio is the "best deserving a fair lady." This conversation creates some suspense as the audience wonders who Bassanio is and if he will appear since Portia obviously approves of him.