If my biological father dies and there is not a Will, am I entitled to a part of his assets?

When a person dies without a Will they are said to have died "intestate".  Accordingly the laws of the state in which they were domiciled as of the date of their death will prevail.  Typically, under most state intestacy laws, an estate is distributed 1/2-1/3 to a surviving spouse and 1/2-2/3 to the deceased's children. If there is no surviving spouse then the children equally divide the assets.

Now you speak of your "biological father". Where you adopted? If so things may differ from what was explained above.  In some states, an adoption terminates a child's rights to inherit from their biological parent; if other states it does not.  At this point, you should consult directly with a probate attorney.