OCR A-Level Biology - Module 1 revision (A+ GUARANTEED)

What are the resolution and magnification of a light microscope? correct answers R: 200nm M: x1500 what are the resolution and magnification of a TEM? correct answers R: 0.1nm M: x500,000 what are the resolution and magnification of an SEM? correct answers R: 0.1nm M: x100,000 what is the difference between magnification and resolution? correct answers Resolution is the ability to distinguish between two points that are close together, magnification is the degree to which the size of an image is larger than the image itself (image size relative to actual size) why is there a need to stain samples in light microscopy? correct answers - biological material inside the cell is not naturally coloured therefore it is difficult to see - coloured stains are used as the chemicals bind to other chemicals in the organelles and make it easier to distinguish between cellular material how are samples coloured in electron microscopy? correct answers - micrographs start off as black and white - specialised computer program adds colour afterwards what is the function of the nucleus? correct answers houses all of the cell's genetic material in the form of DNA, which is the code needed for protein synthesis. when the cell divides it forms chromosomes what is the function of the nucleolus? correct answers makes ribosomes and RNA which are transported to the cytoplasm and are used in protein synthesis what is the function of the nuclear envelope? correct answers a double membrane with pores to protect DNA from damage within the cytoplasm what is the function of the RER? correct answers provides a large site for protein synthesis by ribosomes and plays a role in transporting proteins what is the function of the SER? correct answers site of synthesis and transportation of lipids, steroids and carbohydrates what is the function of the Golgi apparatus? correct answers modifies proteins received from the RER and packages them into vesicles so that they can be transported