MPs this week accused science minister Lord Sainsbury of being "astonishingly laid-back" about the threat of closure hanging over many university physical science departments.
The House of Commons science and technology committee quizzed Lord Sainsbury on Monday, alongside government chief scientist Sir David King and research councils director-general John Taylor.
Committee members said that they were worried that the government's top-up fees policy could further damage science courses, many of which are already facing the threat of closure because they are struggling to attract sufficient numbers of students.
Labour MP Tony McWalter attacked Lord Sainsbury for not taking more responsibility for the crisis.
Mr McWalter said: "I think this is so astonishingly laid-back, I really do.
In your written response to us about closures, you said the biggest problem is lack of demand from potential students. It seems to me astonishing if you don't feel you can have an impact in changing that."
Lord Sainsbury refused to be drawn on whether universities should charge lower top-up fees for science courses than for arts courses, saying it was a matter for individual universities to decide.
He told the committee that work was needed to make subjects such as physics, chemistry and maths seem more exciting to young people. But he insisted that science courses had to be market-driven.
Lord Sainsbury said: "I can't see value or merit in saying to universities you must run courses where you are not getting the people to do it. The thing that drives this has to be what young people want to do."
He also acknowledged that there were too many researchers working on short-term contracts. He said the growth in science staff numbers over the past three years had been almost entirely in the form of temporary contracts, which were seen by vice-chancellors as the more secure option.
"This was not an efficient way to do it," he said.
Committee chairman Ian Gibson urged Lord Sainsbury to set a target for the maximum number of research staff on temporary contracts.
But Lord Sainsbury said: "I'm not sure how you'd make that calculation - though I have no reservation in saying (the number) is too high."
When pushed about the forthcoming spending review, Lord Sainsbury conceded that it would be a "tough" settlement for science, although he declined to comment on the likelihood of the budget being cut.
He said: "I've had no nods and winks about it going down, but no nods and winks about it going up either."
Sir David told the committee that the Office of Science and Technology was about to begin a comprehensive review of science in 12 government departments, starting with the Department for Culture, Media and Sport, which funds the British Museum and the Science Museum, among others.
He admitted: "There are weak and strong departments." And he told the committee that his job was to "simply raise the game in each department".
Lord Sainsbury agreed that there was room for improvement in the departments. He said: "There is an uneven quality of scientific expertise across government."