Name___________________________Date________________________________
IB Biology
02.1: Cell Theory
1. What are the functions of life, as demonstrated by all living organisms?
Responsiveness, adaptability, growth, reproduction, movement, metabolism, absorption,
respiration and excretion.
2. Define the following terms, with examples:
Unicellular: Unicellular is when an organism has only one cell. Examples are bacteria and
amoeba.
Multicellular: Multicellular organisms are organisms with more than one cell. They have special
cells that do different things. Examples are humans and dogs.
Acellular: Acellular is when the organism has no cell. An example is a virus.
3. Why are viruses often considered non-living?
They are considered non-living because when they are not in contact with a cell, they remain
dormant and do not partake in any biological activity.
4. Outline the three fundamental statements of cell theory
i. All living things are made of cells.
ii. Cells are the smallest units of life.
iii. Cells come only from other cells.
5. What is the significance of the discoveries made by Antonie van Leeuwenhoek and Robert
Hooke?
They discovered that everything is made of cells.
Adapted from Stephen Taylor
http://sciencevideos.wordpress.com
Name___________________________Date________________________________
IB Biology
02.1: Cell Theory
6. For many years, scientists thought that new organisms came about through ‘spontaneous
generation’. Outline the idea of spontaneous generation and the experiments carried out by
Pasteur and Remak to refute this idea.
Spontaneous generation was the idea that living organisms came from food and other organic
matter. Pasteur prevented airborne particles from touching a nutrient broth, he prevented the
growth of the microbes. Leaving it open allowed them to grow.
7. Some types of cell seem to break the laws of cell theory.
a. Give two examples of cells which are multinucleated : one example is muscle cells, and
another is fungal hyphae.
b. Why are viruses often considered ‘acellular’ or even non-living? : They are considered nonliving because they only reproduce when they have infected a cell.
8. Complete this table of SI units of length:
Metric Equivalent
Whole
scientific notation
Unit
Abbreviation
kilometer
km
1 000 m
103 m
meter
m
1m
-
centimeter
cm
0.01
10-2 m
millimeter
mm
0.001 m
10-3 m
micrometer
μm
0.000 001 m
10-6 m
nanometer
nm
0.000 000 001
m
10-9 m
9. The diagram below shows the characteristic rod-shaped structure of E. coli bacteria.
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Name___________________________Date________________________________
IB Biology
02.1: Cell Theory
a. What is the magnification of the image?
28 mm = 28,000/2 = 14,000 m
b. By which method (shown here) do bacteria
reproduce?
They reproduce through division.
10. What is the actual size of the structures delineated in yellow?
1 = 60 ųm 2 = 17 ųm 3 = 275 ųm 4 = 300 ųm
11. Calculate the magnification of these scale bars:
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Name___________________________Date________________________________
IB Biology
02.1: Cell Theory
A = 10,000 X B = 298.5 X C = 390,000 X D = 390 X E = 460 X F = 0.46 X G = 6.6 x 10-5 X
12. What is the magnification of these images?
a. Scale bar 10µm measures 40mm on the image. 4,000 x
b. Scale bar 5µm measures 25mm on the image. 5,000 x
12. A micrograph has a scale bar of 2µm, which measures 40mm on the image. Measuring the
maximum length of the cell in the image, the ruler reads 180mm. How long is the cell?
180,000/20,000 = 9 ųm
13. A student views an image of a cell magnified 350 times. The image is 250mm long. What is the
actual length of the sample in the image?
714.3 ųm
Adapted from Stephen Taylor
http://sciencevideos.wordpress.com
Name___________________________Date________________________________
IB Biology
02.1: Cell Theory
14. Compare the sizes of these structures. Use SI units.
Plant
cell
Animal
cell
nucleus
bacteria
Mitochondria
virus
ribosome
Membrane
thickness
molecules
10 – 100
ųm
10 – 30
ųm
3 – 18
ųm
1 – 5 ųm
5 – 10
ųm
10 – 300
nm
20nm
2.5 nm
0.278
nm
15. Use some of these electron microscope resources to view molecules, cells and structures and to
practice calculating magnifications and actual sizes.
Virtual Electron Microscope: http://virtual.itg.uiuc.edu/
Microscopy UK: http://www.microscopy-uk.org.uk/
16. As the volume of a cell increases, what happens to…? (increase/ decrease)
a. Production of waste products. The production would increase.
b. Usage of nutrients and oxygen. The usage would increase.
c. The surface area: volume ratio. The ratio would decrease.
17. What are the advantages of maximizing the surface area: volume ratio in a cell?
The advantage is that diffusion is more efficient and it’s easier for concentration gradients to
generate.
18. What strategies do cells use to maintain an efficient SA:Vol?
To maintain an efficient surface area to volume ratio, cells divide.
19. What are some of the ways in which larger organisms maximize SA:Vol?
Some organs fold up to maximize their ratio.
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Name___________________________Date________________________________
IB Biology
02.1: Cell Theory
20. How can a large SA:Vol be harmful or costly to smaller animal species?
Due to the size of the ratio, small animals will have to eat constantly in order to kee p their body
temperature high.
21. How does the invasive Caulerpa algae genus break the rules of SA:Vol?
It breaks the rules because it is a giant single cell with many neclei.
22. Read this article: Giant bacterium with many genomes
http://scienceblogs.com/notrocketscience/2008/04/enormous_bacterium_uses_thousands_of_genome_copies_to_its_ad.php
How does this bacterium cope with being so large?
It feeds on the nutritious fluid in the intestine of its host, as it is symbiotic.
23. Unicellular organisms carry out all the functions of life, multi-cellular organisms differentiate
and show emergent properties.
a. What is meant by the term emergent properties?
Emergent properties are when the parts of an organism are broken down into their
component parts.
b. What are the advantages of cells differentiating to carry out specific functions?
The advantage is that when these functions work together they can benefit the organism as
a whole.
24. All cells in a living organism carry the same genetic information.
a. What is a stem cell?
A stem cell is a type of cell that can turn into any kind of specialized cell when required.
b. What are the following types of stem cells?
Pluripotent: This can turn into any type of cell except the embryonic membrane.
Multipotent: This can change into a number of different cell types.
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Name___________________________Date________________________________
IB Biology
02.1: Cell Theory
Nullipotent: A stem cell that is unable to divide.
c. What type of cell can a liver stem cell become?
25. Outline the process of cell differentiation that leads from an uncommitted stem cell to a
specialized cell, including the role of gene expression. A flow chart might help.
26. Give three examples of specialized cells in multicellular organisms. Describe how their structure
relates to their function.
i.
ii.
iii.
27. Complete the table below to show how stem cells can be used in medicine.
Therapeutic cloning
Used to treat
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Stem cell transplants
Name___________________________Date________________________________
IB Biology
02.1: Cell Theory
Brief method:
Ethical
considerations
Reading:
Stem cells cure sickle cell anemia in mice:
http://medgadget.com/archives/2007/12/scientists_cure_sickle_cell_anemia_in_mouse_model.html
10 amazing medical breakthroughs (read them all):
http://www.time.com/time/specials/2008/top10/article/0,30583,1855948_1863993,00.html
iPS Stem cells used to make human neurons:
http://scienceblogs.com/notrocketscience/2008/08/stem_cells_created_from_als_patient_and_used_t
o_make_neurons.php
28. What are the objections of some groups to the use of embryonic stem cells?
29. How might iPS stem cell technology reduce the need for embryonic stem cells?
Adapted from Stephen Taylor
http://sciencevideos.wordpress.com