A sample of an unknown unicellular pathogen is isolated from a patient and analyzed under a high-resolution transmission electron microscope. Which of the following structural observations would definitively classify the pathogen as eukaryotic rather than prokaryotic?
A cell wall surrounding the outer surface of the plasma membrane.
Ribosomes distributed throughout the cytoplasm.
A membrane-bound organelle containing highly folded inner membranes (cristae).
A circular strand of DNA located within a distinct region of the cytoplasm.
Practise OCR GCSE Biology Cell structures with exam-style questions for Foundation and Higher tier. 69 questions, matched to the OCR GCSE Biology (J247) specification and written in the written papers style. Every question includes a full worked solution and mark scheme, so you can see where marks are awarded rather than just whether you got the answer right.