Secondary Chemistry Teachers of New Zealand co-chairman, Ian Torrie, said members' reaction to the plan was strong.
"It is very strong language, very strongly opposed to the proposals," he said, adding that about 96 per cent of feedback to the association was against the plans.
Torrie said the proposal would leave science with just four level 1 achievement standards covering the ideas that underpin the subject, but not specific knowledge about subjects like physics and chemistry.
Even schools that currently taught general science at level 1 offered achievement standards in chemistry and physics and the ministry should change its proposal to include them, he said.
The four proposed standards were also focused on reports, which many students would not enjoy, Torrie said.
He also said science was being cut from six subjects at level 1 to just two, while much smaller cuts or none at all were proposed for other learning areas.
"We're concerned that future students will be able to choose a course from 10 languages, five arts, five social sciences, four technologies but there's only one science subject that they can do," he said.
"We're really concerned that this will have huge impacts on future numbers of science, engineering and medical graduates."
If the proposal went ahead many schools were likely to stop using NCEA to assess science at all, instead opting for other qualifications such as the Cambridge international exams, Torrie said.
President of the New Zealand Institute of Physics, Natalie Plank, said teachers were shocked by the proposed changes.
"There are a couple of issues at play here. I think what has got our physics teaching community very upset is a lot to do with the process of how this has been announced.
"I think the decision to merge all these subjects into level 1 science - it wasn't really clear that was going to happen."
Plank said they also have issues with how the assessment will be done.
"A lot of our science in physics is very additive. We want to build a really strong foundation in our core subject, so a lot of this comes from assessments that are based on conceptual understanding.
"The new standards are all based on the nature of science and the process of science. We're not saying that is a necessarily bad thing - but we do feel that we've gone from one extreme to the other. That this isn't giving a balanced education for our students.
"What we'd like to see is a bit more balance, not just changing everything in quite a dramatic way. For science, and especially physics, these changes are extremely dramatic.
"This would be the first time in the world, to our knowledge, that you would look at assessing physics like this."
Association of Classical Teachers president, Rob Griffiths, said its members were outraged by the proposal.
He said many students studied classics at level 1 and dropping it in favour of a foundational history course was ironic.
"Classics is a broad foundational subject that introduces students to the history of Western civilisation. It touches on art, literature, philosophy, religion and we just don't understand why the subject which is probably the very definition of the foundations of Western literature and Western education would be chopped."
The plan to drop Latin from all levels of the NCEA was likely to kill the subject entirely, Griffiths said.
Students could study it through foreign qualifications like the International Baccalaureate but he doubted that would happen.
"It would be more or less the death knell."
"If the subject is only offered for one qualification pathway then it's unlikely they're going to study it at a younger age because it effectively narrows down their options. Latin gone at NCEA is in my opinion killing it off for all students studying all qualifications."
The ministry also proposed merging accounting, economics and business studies at level 1 into a single subject called commerce.
The Commerce and Economics Teachers Association told its members in a newsletter that would provide only surface learning and make the transition to specialist subjects at level 2 more challenging.
Consultation on the proposed subject changes closes on April 20.
