9700/13 Biology Oct Nov 2011 Online Test | Cambridge AS and A Level MCQ

Which steps are needed to find the actual width of a xylem vessel viewed in transverse section using a ×40 objective lens?
1) Convert from mm to μm by multiplying by 10–3.
2) Calibrate the eyepiece graticule using a stage micrometer on ×10 objective lens.
3) Measure the width of the xylem vessel using an eyepiece graticule.
4) Multiply the number of eyepiece graticule units by the calibration of the eyepiece graticule.