Using a microscope and magnificationIB MYP Sciences: Mind map

Exam questions on Using a microscope and magnification

1. A student in Mumbai is using a light microscope for the first time to look at a prepared slide of onion cells. The microscope has an eyepiece lens of magnification ×10, three objective lenses (×4, ×10 and ×40), a stage, a coarse focus knob and a fine focus knob.
   Explain why the student should start by looking at the slide with the lowest-power objective lens.2 marks
2. A technician in Cape Town prepares a temporary slide of the thin, transparent skin from the inside of an onion bulb. She has forceps, a dropper of water, iodine solution, a microscope slide and a cover slip.
   Describe how the cover slip should be placed on the specimen, and give the reason for this.2 marks
3. A student in Seoul observes cheek cells under a light microscope and makes labelled drawings. Her teacher asks her to calculate the magnification of each drawing so that other students can work out the real size of the cells.
   One cheek cell in her drawing is 60 mm wide. Its actual width is 0.03 mm. Calculate the magnification of the drawing.3 marks