The Labour Party and a leading parents' group have demanded an inquiry into Leaving Cert marking in light of indications that some subjects are much "easier" than others.
This year's results show the percentage achieving an honours grade in higher level papers varies widely: in physics the figure was 66 per cent whereas in music it was 98 per cent.
Also notable in the results this year are the relatively low grades achieved by students taking ordinary-level papers.
Few were awarded very high grades, which were plentiful at the higher level.
Ms Jan O'Sullivan, Labour's spokeswoman on education, called for the State Examinations Commission to order an extensive review of the marking systems employed "to ensure there is equality and fairness in the system.
"There is still some concern that certain students are opting for \ considered [to be\] marked less harshly than others. That perception, whether real or imagined, should be cleared up and students should be assured that their exams will be marked fairly and appropriately, regardless of the subjects they are studying," she added.
Ms Barbara Johnston, of the Congress of Catholic Secondary Schools Parents' Association (CSPA), last night said the Minister for Education must investigate this trend.
The group expressed concern about "the continuing disparity in the results achieved at higher level and at ordinary level. Figures show students taking pass papers are more likely to fail and less likely to get an A".
Ms Johnston said: "I would ask the Minister to determine if schools are unconsciously diverting the best resources to students taking honours in an effort to make their school academically attractive.
"CSPA recognises that demand from parents and the media could be putting increasing pressure on schools to achieve higher points," she added.
Meanwhile, Fine Gael's deputy education and science spokesman, Mr David Stanton, has expressed concern at figures showing a significant drop in CAO applications for third-level science courses.
"I am deeply concerned at the fall-off in CAO applications for science and applied science subjects at third level. A drop in applications of almost 1,500 on last year's applications is very unwelcome, and could signal future difficulties for our economy," he said.
IBEC, the employers' body, says it is concerned that the numbers sitting science-related subjects may be too low to meet the needs of the economy.
The confederation says a comprehensive review of the State's science curriculum, teaching methods and supports - including laboratory infrastructure and information technology facilities - as well as practical assessment should be undertaken as a matter of priority.
