The head of an influential Parliamentary committee has condemned controversial proposals to stop practical science work counting towards A-level grades as “daft”.

The criticism, from Andrew Miller, chair of the Commons Science and Technology Committee, came as the scientific community stepped up its opposition to the decision to give A- level practicals simple pass/fail marks, separate from overall grades.

Representatives of leading scientific societies, universities, industry, academics and headteachers, appearing before the committee, warned exams regulator, Ofqual, that its plan would damage practical work in schools and called on the watchdog to “think again”.

Mr Miller said: “My instant reaction when I read one report [on the plan] was ‘This is daft’.” The Labour MP told Ofqual chief regulator, Glenys Stacey, that he wanted to give her the chance to convince him he was wrong.

But he added: “I am firmly of the view that practical knowledge of how science works is equally as valuable as theoretical. It seems that [your] proposals will in the eyes of many not achieve the goal that you are seeking.”

Ms Stacey argued that new requirements in the A-level science exams meant it would “no longer be possible for students to obtain the best of grades in any of the science subjects unless they have sufficient understanding and experience of experimentation”.  

She was backed by education minister Elizabeth Truss, who told the committee hearing last week that the proposals, which will require students to carry out 12 separate practical activities over their two year A-level science courses, would offer more “transparency” about their skills to universities and employers.

“I haven’t seen an alternative workable proposal that will deliver reliability [and] validity,” Ms Truss added. “I don’t think there is a [better] proposal out there. I think that’s the problem… I think if there was Ofqual would have considered it.”

But the minister revealed she had not discussed the issue with university deans of science or with the government’s chief scientific adviser, Sir Mark Walport, who has warned that plans risk “a further downgrading of practical skills”.

It also emerged that the Department for Education currently does not have its own scientific adviser despite the fact that all government departments are supposed to.

Asked whether and when the vacancy would be filled, Ms Truss said: “That is a very interesting point and I will take that back to the department.”

Ofqual unveiled its plans to remove practical science grades from new A-levels being introduced from September 2015, last month. But the watchdog’s own consultation results revealed that less than a fifth of respondents agreed with the idea and just two out of five exam boards. 

The scheme is designed partly to counter concerns about coursework cheating and over generous teacher marking. Ms Stacey has said that Ofqual is “very attracted” to using the same approach for GCSE sciences. 

Schools would be subject to visits from exam boards to check that laboratory experiments take place, under the plan.  But Ofqual still has a lot of work to do to convince the science community.

Ian Hayes, from the UK Deans of Science, told the committee the plan would not “stretch the most able candidates” and would not show whether or not they were good at practical science.

The Campaign for Science and Engineering  director, Sarah Main, described the proposal as “a huge gamble” with students’ lives, that was likely to lead to a diversion of school resources away from practical work.

Professor Julia Buckingham the chair of SCORE, representing a group of leading scientific societies, agreed and said it was “a policy without any evidence to support it”.