[Maximum number: 1]

Which statements about light microscopes are correct?
1 To calculate the magnification of a light microscope, the eyepiece lens and objective lens magnifications are added together.

2 The resolution of a light microscope is limited by the wavelength of light.
3 The divisions on the scale on a stage micrometer are closer together than the divisions on the scale on an eyepiece graticule.

A

1, 2 and 3

B

1 and 2 only

C

2 only

D

3 only

[Maximum number: 1]

Which steps are needed to find the actual width of a xylem vessel viewed in transverse section using a $\times 10$ objective lens?

1 Convert from mm to $\mu \mathrm{m}$ by multiplying by $10^{-3}$ .
2 Calibrate the eyepiece graticule using a stage micrometer on a × 4 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.

A

1, 2, 3 and 4

B

1 and 2 only

C

2, 3 and 4 only

D

3 and 4 only

[Maximum number: 1]

The diagram shows a transverse section through a blood capillary.

What is the magnification of the drawing?

A

$\times 200$

B

$\times 245$

C

$\times 500$

D

$\times 5000$

[Maximum number: 1]

The diagram shows a view of an eyepiece graticule being calibrated using a stage micrometer.

Each division on the stage micrometer scale is 0.1 mm .
Which row shows a correct calculation to calibrate each eyepiece graticule unit and shows the appropriate units?

calculation

units

$\frac{0.1}{27} \div 1000$

mm

$\frac{0.1}{52} \times 1000$

$\mu \mathrm{m}$

$\frac{0.2}{54} \times 1000$

$\mu \mathrm{m}$

$\frac{0.2}{79} \times 1000000$

nm

[Maximum number: 1]

In an electron micrograph, the length of a mitochondrion is measured as 17.1 cm . The magnification of the electron micrograph is $\times 38000$ .

What is the actual length of the mitochondrion?

A

$0.22 \mu \mathrm{~m}$

B

$0.45 \mu \mathrm{~m}$

C

$2.22 \mu \mathrm{~m}$

D

$4.50 \mu \mathrm{~m}$

[Maximum number: 1]

A light microscope is used to observe two structures that are 200 nm apart on the slide.
What is the actual distance between the two structures when the magnification is changed from $\times 40$ to $\times 400$ ?

A

$2 \mu \mathrm{~m}$

B

$20 \mu \mathrm{~m}$

C

200 nm

D

2000 nm

[Maximum number: 3]

Smilax china is a herbaceous plant.
Fig. 1.1 shows part of a transverse section of a root of S. china with root hair cells visible.

Fig. 1.1

(a)

Name the type of microscope that has been used to obtain the image in Fig. 1.1.

[ 1 ]

(b)

Calculate the actual length, in micrometres ( $\mu \mathrm{m}$ ), of the root hair cell labelled in Fig. 1.1. Use the image length of the root hair cell along line X-Y in your calculation.
actual length = $\mu \mathrm{m}$

[ 2 ]

[Maximum number: 1]

An eyepiece graticule can be calibrated using a stage micrometer.
What is the correct reason why an eyepiece graticule is calibrated?

A

An eyepiece graticule can be used to make measurements.

B

An eyepiece graticule is magnified by the objective lens.

C

An eyepiece graticule magnifies the specimen.

D

An eyepiece graticule makes comparisons.

[Maximum number: 1]

A prokaryotic cell which is $1 \mu \mathrm{~m}$ in diameter is magnified 50000 times in an electron micrograph. What is the diameter of the cell in the electron micrograph?

A

$5 \times 10^{-1} \mathrm{~mm}$

B

$5 \times 10^{0} \mathrm{~mm}$

C

$5 \times 10^{1} \mathrm{~mm}$

D

$5 \times 10^{2} \mathrm{~mm}$

[Maximum number: 1]

The diagram shows a stage micrometer scale viewed with an eyepiece graticule, using a magnification of $\times 200$ .

Using the same magnification, a chloroplast is measured as 4 eyepiece graticule divisions long.
How long is the chloroplast?

A

$1.0 \times 10^{1} \mu \mathrm{~m}$

B

$4.0 \times 10^{2} \mu \mathrm{~m}$

C

$2.5 \times 10^{-1} \mu \mathrm{~m}$

D

$2.5 \times 10^{-2} \mu \mathrm{~m}$