Cognitive Science Bsc

I have Pure Maths Physics and Chemistry in A levels. Can I apply for cognitive science major? Do I need biology?

Different unis will have different entry requirements, both in terms of the grades they are seeking and the specific subjects they require.

Having said that, my guess is that you're talking about the University of Edinburgh specifically. They do not require Biology:

"A Levels: ABB."
"A Levels: Mathematics at A. Your Mathematics qualifications must have been achieved no more than two academic years prior to entry. GCSEs: English at C or 4."
(source)

HI. I have also been looking at the Aarhus University. They only mentioned in their website that they need IAL for international students but no specific grade is mentioned.

My knowledge is limited to UK-based universities, unfortunately.

I do note, however, that this page on their web site - on their Bachelor's Degree Programme in Cognitive Science - lists the admission requirements as follows (I've highlighted the interesting parts in red):

"All applicants, both for quota 1 and quota 2, must fulfil the following admission requirements for Cognitive Science:

Qualifying entry examination
You must have a qualifying entry examination.

Specific admission requirements
You must fulfil the following specific admission requirements:

• English B
• Mathematics B
• History B or History of Ideas B or Social Studies B or Contemporary History B
B-level is the Danish subject level, not the grade. We assess your subject levels when you apply.

Grade point Average (GPA) requirement of 6.0 in quota 1
You must have a minimum GPA of 6.0 on the Danish 7-point grading scale in your qualifying examination to be assessed in quota 1.

If you do not have a GPA of 6.0 on the Danish 7-point grading scale, then your application can only be assessed in quota 2."

I suspect Google will be able to help your map your current grades to the Danish 7-point grading scale, potentially via an ECTS grade. Of course, even doing that would only get you the minimum requirement. It may be that most applicants typically exceed the minimum.

but they accept a levels. Why do you say it would only get me the minimum requirements?