A scientist studies cells from a biofilm growing on the inside of a water-treatment pipe. In electron micrographs of these cells, the DNA of each cell forms one circular molecule, and no membrane separates the DNA from the cytoplasm.
Explain whether these cells are prokaryotic or eukaryotic. Predict whether they contain mitochondria, and give a reason for your prediction.
130 exam-style questions on OCR GCSE Biology 1.1 Cell structures, covering 1.1.1 Viewing cells with light microscopes, 1.1.2 Sub-cellular structures and functions, and 1.1.3 Electron microscopy and resolution. Each one has a worked solution and a mark scheme showing where the marks go.