IQ testing

https://en.wikipedia.org/wiki/Raven's_Progressive_Matrices

https://en.wikipedia.org/wiki/Bias_in_Mental_Testing

https://en.wikipedia.org/wiki/Intelligence_quotient

http://wilderdom.com/personality/intelligenceCulturalBias.html

https://geneticliteracyproject.org/2016/07/21/mri-scan-replace-iq-test-measuring-human-intelligence/

https://www.amazon.com/Neuroscience-Intelligence-Cambridge-Fundamentals-Psychology/dp/110746143X

They don't test knowledge. You need a very minimal amount of knowledge for them, such as knowing the language in which it is being delivered, like every test, but they don't test your knowledge they test how well you can reason things out. Pre-requisite competency is assumed in every test, no way around that, every test expects you to have competency in the medium which delivers the questions so citing that says nothing special about IQ. Knowledge does not actually get you through the test, you can be a savant whose brain is a walking encyclopedia with a photographic memory and still do poorly. Because that is not what the test is looking for. And you can read the questions perfectly but still score poorly, test similarly isnt about that.