1.1 - Stem Cells, Cell Theory, & Microscopy

Which statement best describes stem cells?

• A.$\hspace{1em}$ Stem cells cannot be found in the adult body.

• B.$\hspace{1em}$ The foetus is composed only of stem cells.

• C.$\hspace{1em}$ Stem cells can divide and differentiate into different types of specialised cells.

• D.$\hspace{1em}$ Stem cells have undergone specialisation and maturation.

Magnification: 100 x $\hspace{3em}$Scale bar = 10 µm

[Source: Adapted from User: NEON. (2014). Chlorella vulgaris Beijerinck Nies-2170 / Olympus IX71+DP72. Wikimedia Common. Retrieved April 6, 2022, from https://commons.wikimedia.org/wiki/File: Chlorella_vulgaris_NIES2170.jpg. Copyright by CC BY-SA 3.0]

Chlorella contains the molecule chlorophyll which makes it to appear green. What life function is exhibited in this example?

• A.$\hspace{1em}$ Nutrition

• B.$\hspace{1em}$ Reproduction

• C.$\hspace{1em}$ Response

• D.$\hspace{1em}$ Excretion

Which of the following statements are true about the structure of cells?

• I.	All cells contain cytoplasm enclosed by the plasma membrane.
  II.	The microscope was important in understanding the structure of the cell.
  III.	Prokaryotes do not have genetic material.

• A.$\hspace{1em}$ I and II only

• B.$\hspace{1em}$ II and III only

• C.$\hspace{1em}$ I and III only

• D.$\hspace{1em}$ I, II and III

Why do multicellular organisms exhibit emergent properties?

• A.$\hspace{1em}$ All the cells of multicellular organisms have the same function.

• B.$\hspace{1em}$ Cells of multicellular organisms do not communicate with one another.

• C.$\hspace{1em}$ Cells of multicellular organisms interact with one another.

• D.$\hspace{1em}$ Cells of multicellular organisms have similar structures.

Which statement is false about the genome?

• A.$\hspace{1em}$ The genome is an organism’s entire set of genetic material.

• B.$\hspace{1em}$ All the information carried by the genome is expressed in each cell.

• C.$\hspace{1em}$ The genome is a set of instructions to be followed by the cell.

• D.$\hspace{1em}$ Each skin cell contains a full copy of the genome.

The photo shows an Australian shelduck (Tadorna tadornoides).
Which is not a feature that is adapted to aid in locomotion?

[Source: Adapted from Harrison, J. (2023, July 25). Australian shelduck. Wikipedia. Retrieved July 26, 202, from URL https://en.wikipedia.org/wiki/Australian_shelduck. Copyright under CC BY 4.0]

• A.$\hspace{1em}$ Dense bones

• B.$\hspace{1em}$ Wings

• C.$\hspace{1em}$ Webbed feet

• D.$\hspace{1em}$ Oily coating on feathers

Paramecium produces enzymes that catalyse different chemical reactions taking place in the cytoplasm. What function of life is demonstrated in this situation?

• A.$\hspace{1em}$ Excretion

• B.$\hspace{1em}$ Homeostasis

• C.$\hspace{1em}$ Reproduction

• D.$\hspace{1em}$ Metabolism

Some cells are exceptions to the cell theory. In the table below, which information about cells and reasons for them being exceptions is not correct?

Which of the following statements supports the position that using human stem cells for scientific research is ethical?

• I.	Harvesting embryonic cells can advance scientific understanding of cell differentiation.
  II.	An embryo has not yet developed its nervous system; therefore, the process of harvesting stem cells is painless.
  III.	Many embryos made through the process of IVF are never implanted and would otherwise be discarded.

• A.$\hspace{1em}$ I and II

• B.$\hspace{1em}$ II and III

• C.$\hspace{1em}$ I and III

• D.$\hspace{1em}$ I, II and III

What do aseptate fungal hyphae, skeletal muscle, red blood cells, and phloem sieve tube elements have in common?

• A.$\hspace{1em}$ The cells are large

• B.$\hspace{1em}$ They all have no cell wall

• C.$\hspace{1em}$ They all lack a nucleus

• D.$\hspace{1em}$ They are all exceptions to the cell theory

[Maximum mark: 6]

The image below is a micrograph of blood.

Magnification: 800x

[Source: Adapted from Berkshire Community College Bioscience Image Library. (2018). Connective Tissue: Human Blood Leukocyte Survey. Flickr. Retrieved April 4, 2022, from https://www.flickr.com/photos/146824358@N03/26921278147. Copyright free]

1. Identify the part of the cells labelled A and B. [2]
   

2. Outline why blood is classified as a tissue. [1]
   

3. State where the stem cells needed to produce red blood cells are located. [1]
   

4. Progenitor cells are produced by dividing stem cells. These cells will eventually differentiate even further. Blood cells have a common progenitor cell. Describe the process that happens to these progenitor cells. [2]
   

What is the actual width of the cell in this image?

[Source: Adapted from Itayba, Hebrew Wikipedia (2006, March 1). File: Electron Microscope Siemens, 1960.jpg - wikimedia commons. Wikimedia commons. Retrieved March 4, 2023, from https://commons.wikimedia.org/wiki/File: Electron_microscope_Siemens,_1960.jpg Copyright under CC BY 3.0]

• A.$\hspace{1em}$ 4μm

• B.$\hspace{1em}$ 40μm

• C.$\hspace{1em}$ 400μm

• D.$\hspace{1em}$ 4000μm

[Maximum mark: 10]

Pictured below are Robert Remak’s original drawings of cells from a chick embryo.

[Source: Wilson, Edmund B. (1897). The Cell in Development and Inheritance. New York: Macmillan, IV, p46. Retrieved January 4, 2023, from https://archive.org/details/cellindevelopmenwils2. Copyright under Public Domain.]

1. Outline how Remak’s observations supported Louis Pasteur’s findings on spontaneous generation. [3]
   

2. State which characteristic of life is carried out by Euglena in each of the following:

   1. flagella [1]
      

   2. eyespot [1]
      

3. Retinal degeneration can be treated with adult or embryonic stem cells. Compare the advantages and disadvantages of the use of adult and embryonic stem cells. [3]
   

4. Predict the effects of the removal of saprotrophs from an ecosystem. [2]
   

Which of the following statements about the effect of surface area and volume on the cell’s processes is false?

• A.$\hspace{1em}$ The rate at which materials enter or leave the cell depends on the surface area.

• B.$\hspace{1em}$ A small cell will be able to take in sufficient materials by diffusion.

• C.$\hspace{1em}$ The rate at which materials are used and produced depends on the surface area.

• D.$\hspace{1em}$ A large spherical cell will not be able to excrete waste products at a sufficient rate by diffusion.

[Maximum mark: 9]

The image shows an African daisy (Osteospermum acanthospermum), a sessile organism and a Humboldt penguin (Spheniscus humboldti), a motile organism.

[Source: Adapted from Pixabay. (2016, January 21). Purple daisybush flower· free stock photo - PEXELS. Pexels. Retrieved July 26, 2023, from URL https://www.pexels.com/photo/purple-daisybush-flower-36753/. Copyright free]

[Source: Adapted from Tolkein, T. (2010, October 25). File : Humboldt Penguin spheniscus humboldti Newquay Zoo.jpg. Wikimedia commons. Retrieved July 26, 2023, from URL https://commons.wikimedia.org/wiki/File: Humboldt_Penguin_Spheniscus_humboldti_Newquay_Zoo.jpg. Copyright under CC BY 2.0]

1. State one way that a daisy moves. [1]
   

2. State two life processes other than movement that the two organisms have in common. [1]
   

3. Explain three adaptations that the penguin has for efficient movement in water and on land. [3]
   

4. In order to reproduce, the penguin may have to travel to find a mate.

   1. Outline one advantage of travelling to find a mate. [1]
      

   2. Outline one disadvantage of travelling to find a mate. [1]
      

5. State two reasons other than reproduction that the penguin may need to travel. [2]
   

What feature distinguishes fungal hyphae and striated muscle from the two cell types shown in the images?

[Source: Adapted from CNX OpenStax. (2016, May 27). File 04 00 00.jpg. Wikimedia Commons. Retrieved March 5, 2023, from https://commons.wikimedia.org/wiki/File: Figure_04_00_00.jpg Copyright under CC by 3.0]

• A.$\hspace{1em}$ They are multinucleate.

• B.$\hspace{1em}$ They only have one nucleus.

• C.$\hspace{1em}$ They have unusually large cells that contain only one nucleus.

• D.$\hspace{1em}$ They contain mitochondria.

Which statements about unicellular and multicellular organisms are correct?

[Maximum mark: 5]

Below are diagrams of specialised cells (not to scale).

[© Revision village 2022 created with BioRender.com]

1. Put these cells in order of size, from the smallest to the largest. [1]
   

2. Compare and contrast totipotent, pluripotent and multipotent stem cells. [4]
   

[Maximum mark: 8]

1. Outline the steps in calculating the magnification of a micrograph. [4]
   

2. Describe the steps taken to focus on a specimen using the 40x objective lens of a light microscope. [4]
   

[Maximum mark: 3]

Leukemia is a cancer of the bone marrow specifically affecting white blood cells. Outline the steps of how stem cells could be used as a treatment for leukemia.

[Maximum mark: 6]

The diagram below shows a cell.

[Source: Adapted from Gonzalez, R., & Kerfeld, C. (2022, June 13). Synechococcus elongatus. Wikipedia. Retrieved June 19, 2022, from https://en.wikipedia.org/wiki/Synechococcus_elongatus Copyright under CC BY 3.0]

1. 1. Deduce with a reason, what type of cell this is. [1]
      

   2. Calculate the magnification of the cell. [1]
      

   3. Outline two functions of life carried out by the cell in the diagram. [2]
      

2. 1. State the type of microscope used to produce the image. [1]
      

   2. Explain your choice of microscope for part (i). [1]
      

Which of the following is a reason that embryonic stem cells are not used in the treatment of leukaemia?

• A.$\hspace{1em}$ They have limited differentiation potential.

• B.$\hspace{1em}$ It is difficult to control which cell type they differentiate into.

• C.$\hspace{1em}$ They are difficult to obtain.

• D.$\hspace{1em}$ They have a higher chance of accumulated mutations.

[Maximum mark: 16]

1. Describe the use of stem cells to treat Stargardt's disease. [4]
   

2. Explain the factors that limit cell size in humans. [4]
   

3. Explain how life functions are performed by Paramecium. [7]
   

The dimensions of a theoretical cube are doubled. By what factor would its volume increase?

• A.$\hspace{1em}$ 2

• B.$\hspace{1em}$ 4

• C.$\hspace{1em}$ 6

• D.$\hspace{1em}$ 8

The table shows the diameters of red blood cells from different organisms. Which red blood cell will have the highest surface area to volume ratio?

[Source: Adapted from Elson, J. A. (2014, December 24). File: Newbloodm.jpg. Wikimedia Commons. Retrieved March 5, 2023, from https://commons.wikimedia.org/wiki/File: Newbloodm.jpg Copyright under CC BY 3.0]

[Maximum mark: 16]

1. Outline the features of cells that do not conform to the cell theory. [3]
   

2. Use named species to explain how unicellular organisms carry out processes of life. [4]
   

3. Compare and contrast the structure of prokaryotic and eukaryotic cells. [8]
   

[Maximum mark: 4]

The diagram below shows a cell.

[Source: Adapted from Gonzalez, R., & Kerfeld, C. (2022, June 13). Synechococcus elongatus. Wikipedia. Retrieved June 19, 2022, from https://en.wikipedia.org/wiki/Synechococcus_elongatus Copyright under CC BY 3.0]

1. Compare and contrast the structure of a mictochondrion with the structure of the cell shown in the diagram. [2]
   

2. Explain why the cell in the diagram is structurally similar to a mitochondrion.[2]
   

What is the correct magnification of this image?

[Source: Adapted from Itayba, Hebrew Wikipedia (2006, March 1). File Microscope Siemens, 1960.jpg - wikimedia commons. Wikimedia commons. Retrieved March 4, 2023, from https://commons.wikimedia.org/wiki/File: Electron_microscope_Siemens,_1960.jpg Copyright under CC BY 3.0]

• A.$\hspace{1em}$ 1000 x

• B.$\hspace{1em}$ 100 x

• C.$\hspace{1em}$ 0.1 x

• D.$\hspace{1em}$ 10000 x

[Maximum mark: 10]

The micrograph shows an image of a plant cell taken with a light microscope.

[Source: Adapted from CNX OpenStax. (2016, May 27). File 04 00 00new.jpg. Wikimedia commons. Retrieved June 14, 2023, from https://commons.wikimedia.org/wiki/File: Figure_04_00_00new.jpg . Copyright free]

1. Calculate the magnification of the image, showing your work. [2]
   

2. Label, with the letter N, a nucleus in the image. [1]
   

3. The image was taken using a light microscope. State how you deduce this from the image. [1]
   

4. Draw and label a diagram to show how the same type of plant cell shown in the micrograph would appear when examined with an electron microscope. [3]
   

5. State two differences that would be seen when looking at an electron micrograph of a bacterium cell compared to this plant cell. [2]
   

6. At first, the student who took this image could not see the cell when focusing the microscope. Suggest what may have caused this problem. [1]
   

What is an example of an emergent property?

• A.$\hspace{1em}$ A unicellular organism uses active transport to absorb nutrients.

• B.$\hspace{1em}$ A retinal cell detecting changes in light intensity.

• C.$\hspace{1em}$ The endocrine and nervous system working cooperatively to respond to the environment.

• D.$\hspace{1em}$ A single muscle cell contracting.

The electron micrograph shows a prokaryotic cell, Cyclotella litoralis. What is the actual diameter of the cell in this image?

[Source: Adapted from FWC Fish and Wildlife Research Institute. (2011, June 7). Cyclotella litoralis (scanning electron micrograph). Flickr. Retrieved March 5, 2023, from https://www.flickr.com/photos/myfwc/5808259556 Copyright under CC BY 3.0]

• A.$\hspace{1em}$ 3.5 cm

• B.$\hspace{1em}$ 350 µm

• C.$\hspace{1em}$ 3500 mm

• D.$\hspace{1em}$ 35 µm

The electron micrograph shows a sarcomere, the smallest functional unit of striated muscle tissue. What is the actual length between the two Z lines?

[Source: Adapted from Loison, O., Weitkunat , M., Kaya-Çopur , A., Nascimento Alves, C., Matzat , T., & Spletter , M. L. (2018). Category: sarcomeres. Wikimedia Commons. Retrieved March 5, 2023, from https://commons.wikimedia.org/wiki/Category Copyright under CC BY 3.0][Ruler tool, cm]

• A.$\hspace{1em}$ 10 µm

• B.$\hspace{1em}$ 1 mm

• C.$\hspace{1em}$ 1 cm

• D.$\hspace{1em}$ 1 µm

Which row in the following table gives the correct disadvantages of the different stem cell sources for therapeutic uses?

The giant algae Acetabularia can be a model organism for studying the biology of a plant cell. Which characteristics of Acetabularia make it a good model organism?

• A.$\hspace{1em}$ Both, Acetabularia cells and plant cells, do not have a cell wall.

• B.$\hspace{1em}$ Acetabularia is composed of one large cell.

• C.$\hspace{1em}$ Acetabularia is composed of many large cells.

• D.$\hspace{1em}$ Acetabularia contains a pigment which makes its structures easily visualised.