yacomine_02.1 cell theory (2)

Name Joseph Yacomine___________Date ________________________________IB Biology

02.1: Cell Theory1. 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

http://sciencevideos.wordpress.com/


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 non-living because they only reproduce when they have infected a cell.

8. Complete this table of SI units of length:

Unit Abbreviation Metric EquivalentWhole scientific notation

kilometer km 1 000 m 103 m

meter m 1 m -

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 nm0.000 000 001

m10-9 m

9. The diagram below shows the characteristic rod-shaped structure of E. coli bacteria.




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:




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




02.1: Cell Theory

14. Compare the sizes of these structures. Use SI units.

Plant cell

Animal cell

nucleus bacteria Mito-chondria 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.




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 genomeshttp://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.



http://scienceblogs.com/notrocketscience/2008/04/enormous_bacterium_uses_thousands_of_genome_copies_to_its_ad.php


02.1: Cell Theory

Nullipotent: A stem cell that is unable to divide.

c. What type of cell can a liver stem cell become?The type of cell that a liver stem cell can become is pancreatic cells.

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. Red Blood Cell:- Its flattened top increases surface area by volume ratio, and it is flexible so it can squeeze through capillaries.

ii. White Blood Cell:- It is designed to surround and destroy harmful substances, so its structure is designed so it can bend.

iii. Cardiac Muscle:- The cardiac muscle connects heart muscle cells together using intercalated disks, allowing the heart to beat.

27. Complete the table below to show how stem cells can be used in medicine.

Therapeutic cloning Stem cell transplants

Used to treatBrain Disease Cancer




02.1: Cell TheoryBrief method: Genetic material from an adult’s cell is

put into an empty egg cell through injection. They then put master cells inside which have the capability to develop into different cell types.

Healthy stem cells are infused into a body.

Ethical considerations

Religious groups, including Christians believe that stem cell research, and the use of stem cells to benefit the life of another human being to be unethical as no life is more important than another and to take a life to enhance a life is unethical, with little difference to murdering another being.

The use of stem cell as experimental material can be viewed as inhumane as they are taken from an embryo which would grow to be a human being. Taking the stem cells is no different from taking a human life.

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

28. What are the objections of some groups to the use of embryonic stem cells?

One must first kill an embryo in order to harvest its stem cells, therefore there are ethical objections from certain religious groups whom believe that killing a human being in order to benefit another life is unethical.

29. How might iPS stem cell technology reduce the need for embryonic stem cells?IPS stem cell technology reduces the need for embryonic stem cells because using the technology they can create motor neurons which are similar to embryonic stem cells, hereby bypassing the objections that some groups have on the usage of embryonic stem cells.



http://scienceblogs.com/notrocketscience/2008/08/stem_cells_created_from_als_patient_and_used_to_make_neurons.php

http://scienceblogs.com/notrocketscience/2008/08/stem_cells_created_from_als_patient_and_used_to_make_neurons.php

http://www.time.com/time/specials/2008/top10/article/0,30583,1855948_1863993,00.html

http://medgadget.com/archives/2007/12/scientists_cure_sickle_cell_anemia_in_mouse_model.html


02.1: Cell Theory



yacomine_02.1 cell theory (2)

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