Peace be upon you. If the extra mark given by the teacher is considered cheating in the exams, then it is not permissible to remain silent about it, as cheating in exams is not allowed. However, if the extra mark falls within the teacher's discretion, such as being a substitute for class participation or similar, or if it compensates for the total questions that we deserved, then there is no objection to that. May you be successful in all good things.