[Maximum number: 1]

Smooth muscle is a tissue composed of smooth muscle cells. The cells contain cytoplasm packed with proteins that are involved in contraction and relaxation.

(a)

When viewed in longitudinal section (LS), smooth muscle cells are elongated and taper at both ends. This is known as a fusiform shape. Each cell has a central nucleus, which also appears elongated.

Fig. 1.1 is a diagram of a smooth muscle cell to show the fusiform shape.

Fig. 1.1

A student used a microscope fitted with a calibrated eyepiece graticule to estimate that the length of one smooth muscle cell was 250 micrometres $(\mu \mathrm{m})$ .

[ 1 ]

(i)

Name the type of microscope slide that the student used to calibrate the eyepiece graticule.

[ 1 ]

[Maximum number: 1]

The eyepiece lens of a microscope can be fitted with an eyepiece graticule.
Which of these statements about eyepiece graticules are correct?
1 They measure the actual length of cells in micrometres.
2 They help biologists to draw cells with correct proportions.
3 They change in size when the objective lens is changed from $\times 10$ to $\times 40$ .

A

1, 2 and 3

B

1 and 3 only

C

1 only

D

2 only

[Maximum number: 1]

What are the appropriate units for measuring diameters of alveoli, diameters of white blood cells and the width of cell walls?

diameters of alveoli

diameters of white blood cells

width of cell walls

mm

$\mu \mathrm{m}$

mm

$\mu \mathrm{m}$

nm

mm

nm

[Maximum number: 1]

The eyepiece of a microscope is fitted with an eyepiece graticule and a stage micrometer scale is placed on the microscope.

Which statements about the stage micrometer scale are correct?
1 It allows you to measure the actual length of cells.
2 It allows you to calibrate the eyepiece graticule.
3 It changes in size as the objective lens changes from $\times 10$ to $\times 40$ .

A

1, 2 and 3

B

2 and 3 only

C

1 only

D

2 only

[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]

Which structure is measured in the units shown using a light microscope?

structure

unit

cell surface membrane

nm

cell wall

nm

chloroplast

$\mu \mathrm{m}$

ribosome

$\mu \mathrm{m}$

[Maximum number: 1]

Which size ranges can be viewed using a light microscope?

A

4 only

B

1 and 2 only

C

2 and 3 only

D

3 and 4 only

[Maximum number: 1]

Using a stage micrometer scale, one unit of an eyepiece graticule was calculated as 0.005 mm . The diameter of a spongy mesophyll cell was counted as 3.5 units on the eyepiece graticule.

What is the estimate of the diameter of the cell?

A

$0.18 \mu \mathrm{~m}$

B

$1.8 \mu \mathrm{~m}$

C

$18.0 \mu \mathrm{~m}$

D

$180 \mu \mathrm{~m}$

[Maximum number: 1]

Which steps are needed to find the actual width of a xylem vessel viewed in transverse section using a $\times 40$ 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 $\times 10$ 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.

A

1, 2, 3 and 4

B

2, 3 and 4 only

C

1 and 2 only

D

3 and 4 only

[Maximum number: 1]

The eyepiece lens of a microscope is fitted with an eyepiece graticule.
Which statements about the graticule are correct?
1 It allows you to measure the actual length of cells.
2 It allows you to draw cells with correct proportions.
3 It changes in size as the objective lens changes from × 10 to $\times 40$ .

A

1, 2 and 3

B

1 and 3 only

C

1 only

D

2 only