Hello Umar, I believe there are many answers to your question, depending on your classroom/teaching/grade level. For example, here in the US, we have many "inclusion" classes in the sciences, which means that students of all academic levels can be in the same class. However, in such situations, learning is always enhanced by the presence of teacher's aides, or para-professionals. There is no doubt that students with low literacy need special help in the sciences.
One thing that is difficult is the science vocabulary; in biology for example, in one academic year, I counted well over 150 new words/names/phrases that were seen in both lessons and exams. Being prepared for this, was essential.
I also noticed that the more hands on labs and such that could be done in class, the less literacy played a factor. There is no doubt that they can definitely achieve competency, as noted in the response above. The real test of this of course would be, "Are such individuals going to be prepared to seek an occupation in science?"
Your areas of instruction, as listed with your name, will be one key to the future for such individuals.
Yes, in maths, painting, sculpture, music, sports,etc. If low literacy means poor reading,could be only dyslexia, if it is poor writing, could be only dysgraphia.( common example, Einstein was dyslexic). Even if a person has a mental disability (not severe, of course), could have some competence in a field or another.