Agregar asterisco en la clase de examen

Question

Estoy escribiendo un ejercicio para estudiantes que usan examclass. Quiero que alguna pregunta sea un ejercicio después de clase y lo indico poniendo un asterisco después del número de la pregunta, algo así como (a)*. Lo intenté \part[*], pero esto dará (* point). ¿Qué puedo hacer, por favor? ¡Gracias! Mi código es el siguiente.

\documentclass[english]{exam}

\usepackage[T1]{fontenc}
\usepackage[utf8]{inputenc}
\usepackage{babel}
\usepackage{bigints}
\usepackage{amssymb}
\usepackage{amsthm}

\begin{document}

\begin{questions}

\question

\begin{parts}

\part $*$ bla bla

\end{parts}

\end{questions}

\end{document}

Answer 1

A continuación se muestra una forma de definir dos comandos \afterclassparty \standardpartdarle el formato deseado:

\documentclass{exam}

\newcommand\afterclasspart{\renewcommand\partlabel{(\thepartno)$^\ast$}}  
\newcommand\standardpart{\renewcommand\partlabel{(\thepartno)}}
  
\begin{document}

\begin{questions}
\question[10]
Why is there air?
\question
What if there were no air?
\begin{parts}
\part[5]
Describe the effect on the balloon industry.
\afterclasspart
\part[5]
Describe the effect on the aircraft industry.
\standardpart
\part[5]
Describe the effect on the wool industry.
\end{parts}
\question[20]
\begin{parts}
\afterclasspart
\part
Define the universe.
Give three examples.
\standardpart
\part
If the universe were to end, how would you know?
\part
If the universe were not to end, how would you know?
\end{parts}
\end{questions}

\end{document}

El resultado:

Quizás esta variante dé una mejor alineación a las etiquetas:

\documentclass{exam}

\newcommand\afterclasspart{\renewcommand\partlabel{(\thepartno)\makebox[0pt]{$\ ^\ast$}}}  
\newcommand\standardpart{\renewcommand\partlabel{(\thepartno)}}
  
\begin{document}

\begin{questions}
\question[10]
Why is there air?
\question
What if there were no air?
\begin{parts}
\part[5]
Describe the effect on the balloon industry.
\afterclasspart
\part[5]
Describe the effect on the aircraft industry.
\standardpart
\part[5]
Describe the effect on the wool industry.
\end{parts}
\question[20]
\begin{parts}
\afterclasspart
\part
Define the universe.
Give three examples.
\standardpart
\part
If the universe were to end, how would you know?
\part
If the universe were not to end, how would you know?
\end{parts}
\end{questions}

\end{document}

El resultado:

Actualizar

Se puede aplicar un procedimiento similar para agregar el asterisco a las preguntas seleccionadas:

\documentclass{exam}

\newcommand\afterclasspart{\renewcommand\partlabel{(\thepartno)\makebox[0pt]{$\ ^\ast$}}}  
\newcommand\standardpart{\renewcommand\partlabel{(\thepartno)}}
\newcommand\afterclassquestion{\renewcommand\questionlabel{\thequestion.\makebox[0pt]{$^\ast$}}}  
\newcommand\standardquestion{\renewcommand\questionlabel{\thequestion.}}  

\begin{document}

\begin{questions}
\afterclassquestion
\question[10]
Why is there air?
\standardquestion
\question
What if there were no air?
\begin{parts}
\part[5]
Describe the effect on the balloon industry.
\afterclasspart
\part[5]
Describe the effect on the aircraft industry.
\standardpart
\part[5]
Describe the effect on the wool industry.
\end{parts}
\question[20]
\begin{parts}
\afterclasspart
\part
Define the universe.
Give three examples.
\standardpart
\part
If the universe were to end, how would you know?
\part
If the universe were not to end, how would you know?
\end{parts}
\end{questions}

\end{document}