A student prepared a slide of plant epidermis tissue to view under an optical microscope. The student cut a very thin slice of the plant tissue.
Explain why it is important to cut very thin slices of tissue for viewing under an optical microscope.
The student used a microscope with a magnification of ×250 \times 250\,×250 to view the plant cells. They used a ruler with 1 mm graduations to measure the length of several cells on the printed micrograph. The measured lengths of six different cells on the image were: 12 mm, 10 mm, 15 mm, 11 mm, 13 mm, and 11 mm. Calculate the mean actual length, in μm\mu\text{m}μm, of these plant cells. Show your working.
Give the absolute uncertainty associated with taking a measurement using a ruler with 1 mm graduations, assuming the uncertainty is equal to the resolution of 1 mm (due to two readings being taken). Calculate the percentage error for a measurement of 12 mm using this ruler.
