If the respondent does not file a notice of defense or does not appear at the hearing, the agency may take action based upon the respondent’s express admissions or upon other evidence, and affidavits may be used as evidence without notice to the respondent. If the burden of proof is on the respondent to establish that the respondent is entitled to the agency action sought, the agency may act without taking evidence. Nothing in this chapter may be construed to deprive the respondent of the right to make a showing by way of mitigation.