Leaders of the Scottish Green and Scottish Liberal Democrat parties, Patrick Harvie and Willie Rennie, both urged Ms Sturgeon to cancel the exams, in the same way her government has already done for next year's National 5s diet.
However, the First Minister resisted the calls, although she admitted there was a “strong argument” the government should reach a decision on whether they will go ahead sooner rather than later.
The senior exams have already been cancelled in Wales, but Education Secretary John Swinney has said a final decision on whether Highers and Advanced Highers will take place won’t be made until mid-February.
Mr Harvie, who raised the case of a pupil who has already had to self-isolate three times yet faces prelims in a few months’ time, said: “This week the Education Secretary told Parliament that one in four S4-6 pupils have already experienced a Covid-related absence, so it makes no sense to delay the decision on the exam diet any further.
“Young people have experienced enough stress and anxiety this year to last a lifetime. And, as is often the case, it’s those from the most deprived communities who’ve been disproportionately affected.
“So isn’t it time that the First Minister gave teachers and young people the clarity they need and accepted that Higher and Advanced Higher exams cannot go ahead in the coming year?”
Ms Sturgeon insisted the government was considering the issue “very, very carefully”.
She said: “We ideally want Higher and Advanced Higher exams to proceed, but the public health advice must allow that and it must be not just safe to do so, but it must be safe to all learners and we absolutely recognise that.
“We know there is potential for further disruption, which is why contingency plans for Higher and Advanced Higher courses are being developed and the Deputy First Minister has made clear that a final decision on Higher and Advanced Highers will be taken no later than mid-February – but it will be taken sooner than that if the evidence suggests that that is the right thing to do.”
Mr Rennie pointed to the number of pupils and teachers already missing school as a result of Covid-19 – up to 30,000 children and 1,500 staff on any given day.
“That means we need an effective alternative to those Higher and Advanced Higher exams,” he said.
“But to make that happen, teachers and students need plenty of warning. The longer the government waits, the less time teachers have to prepare, the greater the problem becomes.”
He asked if the First Minister would “think again” and cancel the assessments.
Ms Sturgeon said: “It’s important that we take the time to get this right, because that matters to all young people.”
A survey by the National Parent Forum of Scotland published last week found a majority of Scottish parents, 50.6 per cent, believe Higher and Advanced Higher exams should be cancelled, with a decision made before Christmas.
It also found 75 per cent of parents believe it should be announced before Christmas whether the exams will go ahead.