Most Government jobs do have only age criteria and as long as you fulful that age criteria for the Category you belong to, you are eligible for the Government examinations. For example, if you look at UPSC, you should have completed your Graduation in any discipline from a recognised University or Institution. It no where mentions aggregate in Graduation. It only has upper age limit and then there is also age relaxation for Reserved Categories. If you look at the Candidate statistics, there are people who have completed their Graduation through Distance education who apply for UPSC. There are also Candidates who have taken multiple attempts for appearing for UPSC. So when they appear for the first time, they have no gap between their Graduation and the exam. But when they appear for the 3rd or 4th time, there is a gap of atleast 3 years since the time they have completed their Graduation. Inspite of that, they are still eligible for UPSC. Similarly, even if you have a gap after your 12th and even if you took an additional year to complete your Bachelor's degree, as long as you fulfil the eligibility criteria, you can appear for Government exams and also B.Ed.