Sí can be used for a one-word affirmative answer, yes.
¿Estás casado? Sí.Are you married? Yes.
No can be used a one-word negative answer.
¿Te consideras tú mexicano-estadunidense, mexicano, tejano, chicano? No, chicano, no.Do you consider yourself Mexican-American, Mexican, Texan, Chicano? No, Chicano, no.
Nada nothing, nadie no one, and nunca/jamás never may be used in one-word answers, or along with no for emphasis:
Y bueno, siendo tú hispana, ¿alguna vez has sentido algún tipo de discriminación? –No, nunca.And well, being Hispanic, have you ever felt at some type of discrimination? No, never.