3.4.1 Stem cells, pluripotency and totipotency Quiz: Pearson Edexcel Biology A (Salters-Nuffield), Unit 3

The 20 questions

1. What is a stem cell?

   • A red blood cell that has lost its nucleus
   • An undifferentiated cell that can divide and give rise to specialised cell types
   • A fully specialised cell that cannot divide
   • A cell that is always found inside the nucleus of a neuron

2. What does totipotency mean?

   • The ability to form only blood cells
   • The ability of a cell to give rise to every cell type, including those needed for a whole organism
   • The ability to form every cell type except extra-embryonic tissues
   • The ability to form only the cells of a single tissue type

3. What does pluripotency mean?

   • The ability to give rise to all cell types of the body
   • The ability to form only one specialised tissue
   • The ability to form only the cells of the immune system
   • The ability to form a whole organism including the placenta

4. Which cells are totipotent in mammals?

   • Red blood cells in circulation
   • The zygote and the cells of the early embryo before they become committed
   • Fully differentiated skin cells
   • Mature neurons in the adult brain

5. Which statement best describes adult stem cells?

   • They are totipotent and can form a whole organism
   • They cannot divide and only replace mature cells by differentiation
   • They are always found in the embryo and cannot persist into adulthood
   • They are multipotent, able to form a limited range of cell types in their tissue of origin

6. Why are plant cells considered totipotent?

   • Plant cells contain centrioles that direct their differentiation
   • Plant cells have no cell wall, so they can change into any tissue
   • Plant cells are always diploid and can divide without limit
   • Many plant cells can be induced in tissue culture to regenerate a whole plant

7. Which therapeutic use of stem cells is established in medicine?

   • Using totipotent cells to clone whole human organs on demand
   • Haematopoietic stem cell transplants, for example to replace blood-forming cells
   • Growing new limbs from skin cells in a laboratory
   • Replacing all neurons in the brain with embryonic stem cells

8. Why do ethical debates arise about embryonic stem cells?

   • They cause cancer in every person who receives them
   • They are always rejected by the recipient's immune system
   • They can only be grown from the cells of plants
   • Obtaining them usually destroys an embryo

9. A cell can be reprogrammed to become pluripotent. What is such a cell called?

   • A totipotent zygote
   • An induced pluripotent stem cell
   • A multipotent haematopoietic cell
   • A differentiated neuron

10. In which order does potency decrease from the most to least versatile?

    • Unipotent, multipotent, pluripotent, totipotent
    • Totipotent, pluripotent, multipotent, unipotent
    • Pluripotent, totipotent, unipotent, multipotent
    • Multipotent, unipotent, totipotent, pluripotent

11. A stem cell divides to produce two cells, one of which remains a stem cell and one of which becomes specialised. What is this process called?

    • Cytokinesis only
    • Binary fission
    • Asymmetric division
    • Meiosis

12. Which feature defines a stem cell's ability to self-renew?

    • Dividing to produce daughter cells that remain undifferentiated
    • Losing all its organelles before dividing
    • Stopping the cell cycle permanently after the first division
    • Producing only identical cells that are fully specialised

13. A totipotent cell is able to form which of the following?

    • Only red blood cells
    • Only the cells of the heart
    • Only the nervous system
    • A complete organism, including extra-embryonic tissues such as the placenta

14. Which property distinguishes pluripotent embryonic stem cells from totipotent cells?

    • Pluripotent cells are found only in plants
    • Pluripotent cells cannot form extra-embryonic tissues such as the placenta
    • Pluripotent cells are always haploid
    • Pluripotent cells can form a whole organism on their own

15. What is differentiation?

    • The process by which a cell divides to produce identical cells only
    • The process by which a cell loses its genetic material
    • The process by which a cell fuses with another cell to form a zygote
    • The process by which a cell becomes specialised for a particular function

16. A researcher wants a cell type that can form all the cells of the blood but no other tissue. Which potency is most appropriate?

    • Multipotent, within the haematopoietic lineage
    • Pluripotent, because it can form any cell in the body
    • Totipotent, because it can form all tissues
    • Unipotent in the nervous system

17. What does an embryonic stem cell most closely resemble in the early embryo?

    • The inner cell mass of a blastocyst
    • The outer trophoblast layer that forms the placenta
    • The cuticle of a plant leaf
    • The mature myelin sheath of neurons

18. Why is the use of stem cells in therapy a decision for society as well as scientists?

    • Stem cell therapies raise ethical, legal and social questions that depend on public values
    • Stem cells only work in societies that have approved them by vote
    • Stem cell research is controlled by the weather and climate
    • Stem cells can only be used by scientists in the same country

19. A cell is found to have the potential to become any cell of the body except the placenta. Which term describes it?

    • Unipotent
    • Pluripotent
    • Totipotent
    • Multipotent

20. Which statement about stem cell differentiation is correct?

    • Differentiation requires a cell to fuse with another cell
    • Differentiation occurs only in plant cells
    • Differentiation removes most of the DNA from a cell
    • Differentiation is controlled by which genes are expressed, not by a loss of genes from the genome

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