AS
Cambridge (CIE)
Biology
2 hours
15 questions
Structured Questions
The Microscope in Cell
Studies
The Microscope in Cell Studies / Magnification Calculations / Eyepiece Graticules &
Stage Micrometers / Resolution & Magnification / Calculating Actual Size
Easy (5 questions)
/42
Medium (5 questions)
/49
Hard (5 questions)
/43
Total Marks
/134
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Easy Questions
1 (a) Define the term magnification.
(1 mark)
(b) Define the term resolution.
(1 mark)
(c) A student is reading a biology textbook. There is an image of a cell with the magnification
stated as ×10 000.
Describe how the student would calculate the actual length of the cell.
Assume that the student has a ruler which measures in cm and mm.
(3 marks)
(d) The student wanted to make a biological drawing of the photomicrograph of the cell.
State three conventions for biological drawing that the student should follow.
(3 marks)
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2 (a) A student wants to prepare a temporary mount of some cells isolated from the root tip
of a garlic bulb. They placed a thin layer of tissue onto a slide before adding a drop of
iodine and a coverslip.
Explain how the coverslip should be added to the slide.
(2 marks)
(b) State how the procedure described in (a) would differ if animal tissue were being viewed
rather than plant tissue.
(1 mark)
(c) Fig. 1 shows an image as seen down the microscope.
The actual diameter of the structure, labelled X, is 200 µm.
A student used a ruler and measured the length of X as 8 cm.
Fig. 1
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Calculate the magnification of the image.
(2 marks)
(d) Fig. 2 shows a labelled organelle taken using an electron microscope.
Fig. 2
Explain the evidence from Fig. 2 that shows that this is an image from an electron
microscope.
(2 marks)
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3 (a) Table 1 compares some of the features of light and electron microscopes.
Table 1
light microscope
electron
microscope
image is formed using...
light
A
resolution
B
C
magnification
lower
D
can be used to observe organelles as
small as...
mitochondria /
chloroplasts
E
Identify the missing words labelled A-E.
(5 marks)
(b) A student used a light microscope to view a specimen. They wanted to work out the
actual size of the specimen and decided to use a stage micrometer together with an
eyepiece graticule.
Explain why the stage micrometer is needed as well as the eyepiece graticule.
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(2 marks)
(c) The specimen the student wanted to view required a stain.
State why stain is needed for some structures and specimens.
(2 marks)
(d) The specimen also needs to be thin to view with a light microscope.
Explain why.
(1 mark)
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4 (a) Fig. 1 shows a cell as viewed down a scanning electron microscope.
x 400
Fig. 1
In the space below sketch a biological drawing of the field of view. Do not include labels.
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(5 marks)
(b) Identify visible organelles in your biological drawing by adding appropriate labels.
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(5 marks)
(c) The cells in Fig. 1 appear blue when viewed down the microscope lens.
Suggest why.
(1 mark)
(d) State the function of one of the organelles labelled in part (b).
State the name of the organelle to which your answer refers.
(1 mark)
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5 (a) Fig. 1 shows an electron micrograph of ciliated epithelial cells. The actual height of the
cilia cell is 30 µm, and the image height is 28 mm.
Fig. 1
Calculate the magnification used to generate the image. Give your answer to three
significant figures.
(1 mark)
(b) Although cilia can be viewed under a light microscope, they are best seen with an
electron microscope.
Suggest why this is the case.
(1 mark)
(c) When viewed under a light microscope it is hard to distinguish individual cilia.
Explain why.
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(2 marks)
(d) Light microscopes have limitations that make some structures difficult to study in detail.
Electron microscopes also have limitations.
State one limitation of an electron microscope.
(1 mark)
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Medium Questions
1 (a) Fig. 1 is a drawing of part of a plant cell as seen with an electron microscope. The scale
bar (measuring 45 mm in length) on this drawing represents a length of 10 μm.
Fig. 1
Calculate the magnification of the drawing in Fig. 1
(2 marks)
(b) Calculate the actual width of the cell in Fig. 1 from A to B. Give your answer in
micrometres (µm).
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(2 marks)
(c) Fig. 2 is a drawing of a mitochondrion at a magnification of ×20 000. The distance
between points A and B in the diagram is 6.4 cm.
Fig. 2
Calculate the actual length of the mitochondrion in Fig. 2 in micrometres (µm).
(2 marks)
(d) The circumference of a mitochondrion, labelled C in Fig. 2, is 1.5 µm. A student is making
an accurate scale model of a mitochondrion for a school science project and wants to
magnify a mitochondrion 50,000 times.
Calculate (in cm) what the circumference of the student’s model will be.
(2 marks)
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2 (a) A student is given a sample of plant tissue.
Describe how the student would prepare a sample of cells from this tissue to be viewed
using a light microscope.
(3 marks)
(b) Describe how the student in part (a) would then view their sample of cells using a light
microscope.
(4 marks)
(c) Identify two structures in a eukaryotic cell that cannot be identified using a light
microscope.
(2 marks)
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3 (a) Fig. 1 below shows a cross-section of a leaf taken using a light microscope with a
magnification of x250.
Fig. 1
Fig. 1 shows some cell organelles inside the cells of the leaf, but it doesn’t show
structures such as ribosomes or cell membranes.
Use your knowledge of microscopes to explain why this is the case.
(2 marks)
(b) If the leaf sample in Fig. 1 were viewed under an electron microscope, ribosomes and cell
membranes could be viewed clearly.
Explain why.
(1 mark)
(c) Outline the general advantages and disadvantages of using an electron microscope.
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(4 marks)
(d) Fig. 2 below shows an image of algae taken using an electron microscope.
SecretDisc, CC BY-SA 3.0, via Wikimedia Commons
Fig. 2
For the image shown in Fig. 2
(i) Name the type of microscope used to produce this image.
[1]
(ii) Give one piece of evidence to support your answer to part i)
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[1]
(2 marks)
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4 (a) A student decided to produce a biological drawing of a plant cell they were viewed using
a light microscope.
Give four conventions that the student must be sure to follow for their diagram to be
classed as a biological drawing.
(4 marks)
(b) In order to produce a scale line for their biological drawing in part a), the student needs
to calculate the size of each eyepiece graticule subdivision. Fig. 1 shows the field of view
of the light microscope used by the student at a magnification of x200. The student is
told that each subdivision on the stage micrometer represents 10 µm.
Fig. 1
Calculate the distance represented by one subdivision of the eyepiece graticule scale at
this magnification.
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(2 marks)
(c) The student in parts a) and b) wants to be able to draw more detail of the plant cell
infrastructure.
Explain why an electron microscope would give a more detailed image of the plant cell
infrastructure than a light microscope.
(2 marks)
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5 (a) With reference to resolution, explain the limitations of using a light microscope.
(2 marks)
(b) Fig. 1 shows a photomicrograph of onion epidermal cells at a magnification of x250.
Fig. 1
(i) Draw a biological drawing of the cells in Fig. 1.
[5]
(ii) Name three organelles that are not visible in Fig. 1.
[3]
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(8 marks)
(c) One of the cells of the image in Fig. 1 was measured to be 24 mm.
Calculate the actual width of one of the cells in Fig. 1. Give your answer in micrometres
(µm).
(2 marks)
(d) Describe how a student would make a temporary mount of some onion epidermal
tissue.
(3 marks)
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Hard Questions
1 (a) A student used a light microscope to view a specimen. They wanted to work out the
actual size of the specimen, and decided to use a stage micrometer, together with the
ruler visible inside the eyepiece of the microscope (known as the eyepiece graticule).
Outline why a stage micrometer is needed as well as the eyepiece graticule.
(2 marks)
(b) Describe the steps required to calibrate the eyepiece graticule of a light microscope
using a stage micrometer.
(3 marks)
(c) Explain why the steps outlined in part (b) would need to be repeated when the student
changes to a more powerful objective lens.
(2 marks)
(d) Fig. 1 shows the appearance of the scale of a stage micrometer. The length of the whole
scale is 1 mm. Point A shows the point at which the edge of a human cheek cell appears
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in the microscope display. A typical cheek cell has diameter of approximately 50 μm.
Fig. 1
Indicate on Fig. 1, with an arrow labelled B, the position of the opposite edge of the
cheek cell.
(1 mark)
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2 (a) Biologists use two main types of microscope to examine cellular structure: optical
microscopes and electron microscopes.
Give two advantages and two limitations of using electron microscopes to investigate
cell structure.
(4 marks)
(b) Fig. 1 shows an electron micrograph of part of an intestinal epithelial cell.
Fig. 1
Name the structures labelled X.
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(1 mark)
(c) Use the scale bar to calculate the magnification of the drawing in Fig. 1.Show your
working.
(2 marks)
(d) The two mitochondria identified in Fig. 1 appear to be different in shape.
Suggest two reasons for this difference.
(2 marks)
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3 (a) Describe the process of making a temporary mount of a piece of plant tissue that would
allow observation of starch grains within a cell with a light microscope.
(3 marks)
(b) Fig. 1 shows two micrographs.
Photo by Dr. Mae Melvin, CC0, via
Photo by Janice Carr, CC0, via
pixnio.com
pixnio.com
Fig. 1
Compare the images shown by the two micrographs.
(1 mark)
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(c) (i) State the role of the cell type visible in Fig. 1.
[1]
(ii) Explain the adaptations of these cells.
[3]
(4 marks)
(d) A student doctor wanted to take a number of different measurements from a sample of
blood cells in a blood smear.
They used a light microscope with an eyepiece graticule as part of their method, but they
did not use a stage micrometer.
Identify the type of error this would lead to and explain the effect on their data.
(3 marks)
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4 (a) Fig. 2 below shows a stage micrometer scale and an eyepiece graticule in a light
microscope. The upper scale is the micrometer while the lower scale is the eyepiece
graticule.
The length of one division on this stage micrometer is 0.1 mm.
Fig. 2
Calculate the actual length of one eyepiece graticule division using this stage
micrometre. Give your answer in µm and show your working.
(2 marks)
(b) The photomicrograph in Fig. 3 was taken using the same microscope and the same
lenses as part (b).
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The same eyepiece graticule was also used and is shown in Fig. 3.
Fig. 3
Use the calibration of the eyepiece graticule unit from part (a) and the information in the
photomicrograph to estimate the actual length in μm of the region of plant tissue shown
between C and D.
(1 mark)
(c) Draw a biological drawing of at least four cells from Fig. 3, including the cell labelled C-D.
Your drawing should be drawn to scale at x1000 magnification.
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(4 marks)
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5 (a) A typical animal cell is surrounded by a cell membrane with a mean thickness of 8 nm,
measured using electron microscopy.
A light microscope-generated image of the whole cell itself measures 5 cm across at a
magnification of x1250.
Calculate the number of times wider the whole cell is than the thickness of its
membrane.
(3 marks)
(b) A light microscope and an electron microscope were used to examine the contents of a
plant cell.
The light microscope was used at two different magnification settings to produce the
images shown in Fig .1. The electron microscope image is also shown in Fig.1
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In all three images the field of view contained the same piece of biological material.
Fig.1
Suggest reasons for the differences in the appearance of the three images in Fig. 1.
(3 marks)
(c) Give two possible names of cell components that could be shown in Fig. 1.
Assume that the setup of the microscopes and sample preparation has been carried out
to give the best possible view of the specimens under observation in each case.
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(2 marks)
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