Name_______Chloe Troulan________________Date____14th September 2010_________________
IB Biology
02.1: Cell Theory
1. What are the functions of life, as demonstrated by all living organisms?
The functions of life are things that all cells have to go through and they are: Nutrition, growth,
reproduction, response to stimulus, movement, excretion and homeostasis.
2. Define the following terms, with examples:
Unicellular
A unicellular organism is an organism that is capable of all functions of life.
Multicellular
A multicellular organism is an organism that has specialized cells that carry out some of the
functions particularly, but altogether all the functions are covered.
Acellular
An acellular organism is an organism that cannot carry out all of the functions, they invade a
host and use the host’s cells apparatus to survive, these are commonly known as viruses.
3. Why are viruses often considered non-living?
Viruses are often considered non-living because they cannot carry out all of the functions that
living cells can carry out.
4. Outline the three fundamental statements of cell theory
i. All living things are composed of one or more cells.
ii. Cells are organisms basic units of structure and function.
iii. Cells come only from pre-existing cells.
5. What is the significance of the discoveries made by Antonie van Leeuwenhoek and Robert
Hooke?
The significance of the discoveries made by Antonie van Leewenhoek and Robert Hooke is that
we now have the invention of the microscope which helps us improve in our theories about
science and also we can the basis of what cells really are which has allowed us to study them
further and find out more about them.
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 all about how an organism can spontaneously appear from
another, for example maggots can just appear in meat but as we know this is not true. So to
prove that this was not true Pasteur made an experiment by placing the broth into an open
Adapted from Stephen Taylor
http://sciencevideos.wordpress.com
Name_______Chloe Troulan________________Date____14th September 2010_________________
IB Biology
02.1: Cell Theory
beaker and some more in a beaker that stopped the airborne particles from being able to enter.
Once the experiment was done this had proved that bacteria grows on other organisms when
the bacteria from the air is able to enter the organism etc.
7. Some types of cell seem to break the laws of cell theory.
a. Give two examples of cells which are multinucleated
Two examples of cells which are multinucleated are: muscle cells and fungal hyphae.
b. Why are viruses often considered ‘acellular’ or even non-living?
Viruses are often considered acellular or non-living because they cannot carry out all
functions that a multicellular or unicellular organism can.
8. Complete this table of SI units of length:
Metric Equivalent
scientific notation
Unit
Abbreviation
kilometer
Km
1 000 m
103 m
meter
M
1m
-
centimeter
Cm
0.01m
10-2 m
millimeter
Mm
0.001 m
10-3 m
micrometer
Μm
0.000 001 m
10^-6m
nanometer
Nm
0.000000001
10-9 m
Whole
9. The diagram below shows the characteristic rod-shaped structure of E. coli bacteria.
a. What is the magnification of the image?
The magnification of this image is:
M=23mm/2um
M=23000/2
M=11,500X
Adapted from Stephen Taylor
http://sciencevideos.wordpress.com
Name_______Chloe Troulan________________Date____14th September 2010_________________
IB Biology
02.1: Cell Theory
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?
Diatom X 1,000:
As= 50mm/1,000
As=0.05mm
As= 5um
Diatom X 5,000
As= 68mm/5,000
As= 0.0136mm
As= 13.6um
Mosquito head X 200
As= 42mm/200X
As= 0.21mm
As= 210um
Hypodermic needle X 100
As= 29mm/100X
As= 0.29mm
As= 290um
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http://sciencevideos.wordpress.com
Name_______Chloe Troulan________________Date____14th September 2010_________________
IB Biology
02.1: Cell Theory
11. Calculate the magnification of these scale bars:
2um:
M= 17mm/2um
M= 17000/2
M= 8,500 X
67um:
M= 16mm/67um
M= 16000/67
M= 238.80
100nm:
M= 32mm/100
M= 32000000/100
M= 320,000X
100um:
M= 32mm/100um
M= 32000/100
M= 320X
50um:
M= 19mm/50um
M= 19000/50
M= 380X
50mm:
M= 19mm/50mm
M= 0.38mm
M=380X
500m:
M= 27mm/500m
M= 0.027/500
M= 0.000054m
Adapted from Stephen Taylor
http://sciencevideos.wordpress.com
Name_______Chloe Troulan________________Date____14th September 2010_________________
IB Biology
02.1: Cell Theory
12. What is the magnification of these images?
a. Scale bar 10µm measures 40mm on the image.
b. Scale bar 5µm measures 25mm on the image.
13. 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?
14. 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?
15. Compare the sizes of these structures. Use SI units.
Plant
cell
Animal
cell
nucleus
bacteria
Mitochondria
10-100
um
10-30
um
3-18 um
1-5 um
5-10 um
virus
ribosome
Membran
e
thickness
molecule
s
10-300
um
20nm
2.5nm
0.278
nm
16. 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/
Adapted from Stephen Taylor
http://sciencevideos.wordpress.com
Name_______Chloe Troulan________________Date____14th September 2010_________________
IB Biology
02.1: Cell Theory
17. As the volume of a cell increases, what happens to…? (increase/ decrease)
a. Production of waste products.
As the colume of a cell increases the production of waste products increase.
b. Usage of nutrients and oxygen.
As the volume of a cell increases the usage of nutrients and oxygen increase.
c. The surface area: volume ratio.
As the volume of a cell increases the surface area: volume ratio decreases.
18. What are the advantages of maximizing the surface area: volume ratio in a cell?
The advantages of maximizing the surface area: volume ratio in a cell is that diffusion of
nutrients becomes easier.
19. What strategies do cells use to maintain an efficient SA:Vol?
The strategies that cells use to maintain efficient Surface area: Volume ratio is to divide.
20. What are some of the ways in which larger organisms maximize SA:Vol?
Some ways in which larger organisms maximize their SA:Vol ratio are that some organisms fold
up to maximize their ratio.
21. How can a large SA:Vol be harmful or costly to smaller animal species?
A large SA:Vol can be harmful or costly to smaller animal species because small animals would
then have to constantly be eating in order to keep their body temperature high.
22. How does the invasive Caulerpa algae genus break the rules of SA:Vol?
The invasive Caulerpa algae genus breaks the rules of SA:Vol because it is a giant single cell with
many nucleis.
23. 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?
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http://sciencevideos.wordpress.com
Name_______Chloe Troulan________________Date____14th September 2010_________________
IB Biology
02.1: Cell Theory
This bacterium copes with being so large by feeding on the nutritious fluid in the intestine of its
host because it is symbiotic.
24. 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?
The term ‘emergent properties’ means when the different 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 advantages of cells differentiating to carry out specific functions is that when the
functions all work together they end up benefiting the organism all together.
25. 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 be used for any specialized cell when required, it can
turn into any specialized cell.
b. What are the following types of stem cells?
Pluripotent: This type of stem cell can become any type of cell except the embryonic
membrane.
Multipotent: This type of stem cell can become a number of different cell types.
Nullipotent: This type of stem cell is the type that is unable to divide. (red blood cells)
c. What type of cell can a liver stem cell become?
The type of cell that a liver stem cell can become is a cancer cell.
26. 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.
Once a stem cell has differentiated, it can only make more stem cells or the differentiated cell
type. The process of cell differentiation is a result of the expression of different genes. Every
single cell in the body all carry the same genes in their nuclei, the only property that makes a cell
different is which gene is expressed in the cell. The expression of the gene is triggered by
changes and the environment around the cell.
Adapted from Stephen Taylor
http://sciencevideos.wordpress.com
Name_______Chloe Troulan________________Date____14th September 2010_________________
IB Biology
02.1: Cell Theory
27. Give three examples of specialized cells in multicellular organisms. Describe how their
structure relates to their function.
i.
ii.
iii.
28. Complete the table below to show how stem cells can be used in medicine.
Therapeutic cloning
Used to replace tissues lost in disease,
Used to treat burned skin or nerve cells
Stem cell transplants
lymphoma
Brief method: They clone the in-vitro culturing of tissues The bone marrow is destroyed by chemo
using someone’s stem cells.
or radio-therapy. But before this
treatment stem cells are harvested from
the bone marrow and stored. These
harvested cells can then be used to
replace the damaged bone marrow which
then will produce healthy blood cells.
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
_to_make_neurons.php
29. What are the objections of some groups to the use of embryonic stem cells?
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http://sciencevideos.wordpress.com
Name_______Chloe Troulan________________Date____14th September 2010_________________
IB Biology
02.1: Cell Theory
30. How might iPS stem cell technology reduce the need for embryonic stem cells?
Adapted from Stephen Taylor
http://sciencevideos.wordpress.com