Year 12 Bio - Periods 1-2

What is the definition of magnification?

• The real size of the object.

• The number of times larger an image is than the actual object.

• The clarity and detail of the image.

• The size of the microscope lens.

Which formula is used to calculate magnification (M)?

• M = Actual size / Image size

• M = Image size + Actual size

• M = Image size / Actual size

• M = Image size x Actual size

What is the name of the transparent scale placed in the microscope eyepiece to measure cells?

• Stage micrometer

• Ruler

• Eyepiece graticule

• Scale bar

To find the actual size of the divisions on an eyepiece graticule, it must be calibrated. What piece of equipment is placed on the microscope stage for this calibration?

• A ruler

• A cheek cell

• A prepared slide

• A stage micrometer

In the magnification formula M = I / A, what does the 'I' stand for?

• The ideal size

• The observed size of the image

• The instrument's power

• The individual cell

If you need to calculate the actual size (A) of an object, how would you rearrange the magnification formula?

• A = M / I

• A = I x M

• A = I / M

• A = M + I

A key step in many calculations is converting units. How many micrometres (µm) are in 1 millimetre (mm)?

• 10

• 100

• 1000

• 10 000

According to the worked example, what is the first step when using a scale bar on a micrograph to calculate magnification?

• Measure the length of the cell in the image.

• Convert the scale bar's actual size to mm.

• Count the number of cells.

• Measure the length of the scale bar on the image.

Figure 1.10 shows an eyepiece graticule scale. What is this scale used for?

• To measure the magnification directly.

• To measure the size of cells in 'eyepiece units'.

• To change the objective lens.

• To focus the microscope.

In Figure 1.11, two micrographs of the same plant cell are shown at the same magnification. Why might they appear different?

• They were taken with different types of microscopes.

• One is a plant cell and one is an animal cell.

• They are different sections through the cell.

• The magnification is actually different.