How cells specialize, and what stem cells are

Grade 9 Science Worksheet

Circle the best answer.

1. Read this first

   Genes in three cells (model data)

   cell	gene for myosin	gene for hemoglobin	basic-upkeep gene
   muscle cell	on	off	on
   developing red blood cell	off	on	on
   nerve cell	off	off	on

   On means the cell is using the gene. Off means the gene is in the DNA but the cell is not using it. All three cells have a nucleus. Myosin helps muscle cells contract. Hemoglobin carries oxygen in red blood cells.

2. 1.

   Bo reads the card. Which statement does it support?

   • The nerve cell lacks the myosin gene, so it has different DNA
   • The three cells hold the same genes but use different ones
   • The three cells use the same genes, so they should look alike
   • The upkeep gene is on in each, so the three cells are one type

3. Use this

   Genes in two cells (model data), 2 rows. Columns: cell, gene for keratin, gene for myosin, gene for hemoglobin. cell P, a skin cell, on, off, off. cell Q, off, off, on. Both cells are from one person and have a nucleus. On means the cell is using the gene. Off means the gene is in the DNA but unused. Keratin is a protein of the outer skin. Myosin helps muscle cells contract. Hemoglobin carries oxygen in red blood cells.

4. 2.

   Esme reads the card. Cell P is a skin cell. What is cell Q most likely, and why?

   • A skin cell like P, since it holds the keratin gene too
   • A muscle cell, since the myosin gene is in its DNA
   • A developing red blood cell, since its hemoglobin gene is on
   • A cell with different DNA from P, since its genes differ

5. Stem cell rounds (model data)

   round	stem cells	specialized cells
   0	1	0
   1	1	1
   2	1	2
   3	1	3

   A stem cell divides. Each division makes one stem cell and one daughter that specializes. A specialized daughter does not divide again.

6. 3.

   Kira extends the table by one more round. After round 4, how many cells are there, and how many are stem cells?

   • 4 cells in total, 1 of them a stem cell
   • 8 cells in total, 4 of them stem cells
   • 5 cells in total, 0 of them stem cells
   • 5 cells in total, 1 of them a stem cell

7. Growing then specializing (model data)

   round	stem cells	specialized cells
   0	1	0
   1	2	0
   2	4	0

   In the first two rounds, each stem cell divides into two stem cells. In the third round, each stem cell makes one stem cell and one specialized cell. Specialized cells do not divide again.

8. 4.

   Luz follows the table. After the third round, how many stem cells and specialized cells are there?

   • 2 stem cells and 4 specialized cells
   • 4 stem cells and 8 specialized cells
   • 4 stem cells and 4 specialized cells
   • 8 stem cells and 0 specialized cells
9. 5.

   Each round, every stem cell makes one stem cell and one specialized cell. Specialized cells do not divide again. Milo continues the pattern. After the third round, how many specialized cells and stem cells are there?

   • 8 specialized cells and 2 stem cells
   • 4 specialized cells and 2 stem cells
   • 6 specialized cells and 6 stem cells
   • 6 specialized cells and 2 stem cells

10. Use this

    Adult stem cells (real data, from OpenStax Anatomy and Physiology 2e), 2 rows. Columns: adult stem cell, cells it gives rise to. blood-forming (hematopoietic) stem cell in bone marrow, platelets, red blood cells and white blood cells. epithelial stem cell in skin, keratinocytes.

11. 6.

    Noah reads the card. Which statement does it support about the bone marrow stem cell?

    • It is found in young children and lost in adults
    • It gives rise to platelets and blood cells, but not keratinocytes
    • It can give rise to any cell type, including keratinocytes
    • It gives rise to red blood cells but not to white blood cells
12. 7.

    The front reads: stem cells from umbilical cord blood are multipotent. The back is blank. Pia reads that stem cells from umbilical cord blood are multipotent. What does multipotent mean for these cells?

    • They can give rise to several related cell types within a limited range
    • They divide a few times and then stop
    • They are already specialized and cannot give rise to any other kind of cell
    • They can give rise to any cell type in the body

13. Flash card (model data, not to scale)

    The front reads: a bone marrow stem cell divides to make one stem cell and one cell that goes on to become a red blood cell. The back is blank.

14. 8.

    Ren reads the card. Why is it useful that one daughter cell stays a stem cell?

    • It lets that daughter cell become any other cell in the body
    • It lets the marrow stop making blood cells once a child is grown
    • It lets the specialized daughter divide into other cell types
    • It keeps a supply of stem cells that can make more blood cells later

15. Use this

    Plant meristems (real data, from OpenStax Biology 2e), 2 rows. Columns: kind of meristem, what it does for the plant. apical meristem, at the tips of stems and roots, lets the plant grow longer. lateral meristem, lets the plant grow thicker.

16. 9.

    Tala sees a shoot get longer at its tip. Which statement fits the card?

    • No meristem is at work; the shoot lengthens as old cells stretch
    • Permanent tissue is at work, since its cells keep dividing
    • The lateral meristem is at work, since it adds length
    • The apical meristem at the shoot tip is making new cells

17. Use this

    Two kinds of plant tissue (real data, from OpenStax Biology 2e), 2 rows. Columns: tissue, its cells. meristematic tissue, keep dividing. permanent tissue (dermal, vascular and ground tissue), no longer actively dividing.

18. 10.

    Ari says dermal tissue cells keep dividing like shoot tip cells. Does the card support this?

    • Yes, a specialized plant cell can divide into any other kind
    • No, permanent tissue cells have specialized and no longer actively divide
    • No, plants have no cells that keep dividing, so shoot tip cells do not either
    • No, permanent tissue cells divide, but more slowly than shoot tip cells