How cells specialize, and what stem cells are
Grade 9 Science Worksheet
Circle the best answer.
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.
Bo reads the card. Which statement does it support?
- The upkeep gene is on in each, so the three cells are one type
- The nerve cell lacks the myosin gene, so it has different DNA
- The three cells use the same genes, so they should look alike
- The three cells hold the same genes but use different ones
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.
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 cell with different DNA from P, since its genes differ
- A developing red blood cell, since its hemoglobin gene is on
- A muscle cell, since the myosin gene is in its DNA
Body cells and nuclei (real data, from OpenStax Anatomy and Physiology 2e and Biology 2e)
cell nucleus nerve cell has a nucleus skin cell has a nucleus mature red blood cell of a mammal no nucleus Jun writes: all body cells carry the same DNA. Which reply is the most accurate, given the card?
- The claim is wrong, because each cell type carries different DNA
- The claim is right, because a red blood cell keeps its DNA in the cytoplasm
- The claim is right, because each cell uses the same genes too
- Cells with a nucleus share the same DNA, but a mature red blood cell has no nucleus
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.
Kira extends the table by one more round. After round 4, how many cells are there, and how many are stem cells?
- 5 cells in total, 1 of them a stem cell
- 8 cells in total, 4 of them stem cells
- 4 cells in total, 1 of them a stem cell
- 5 cells in total, 0 of them stem cells
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.
Luz follows the table. After the third round, how many stem cells and specialized cells are there?
- 8 stem cells and 0 specialized cells
- 4 stem cells and 8 specialized cells
- 4 stem cells and 4 specialized cells
- 2 stem cells and 4 specialized cells
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.
Noah reads the card. Which statement does it support about the bone marrow stem cell?
- It gives rise to red blood cells but not to white blood cells
- It gives rise to platelets and blood cells, but not keratinocytes
- It can give rise to any cell type, including keratinocytes
- It is found in young children and lost in adults
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.
Ren reads the card. Why is it useful that one daughter cell stays a stem cell?
- It lets the marrow stop making blood cells once a child is grown
- It keeps a supply of stem cells that can make more blood cells later
- It lets that daughter cell become any other cell in the body
- It lets the specialized daughter divide into other cell types
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.
Tala sees a shoot get longer at its tip. Which statement fits the card?
- The apical meristem at the shoot tip is making new cells
- 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
Use this
Plant tissues (real data, from OpenStax Biology 2e), 3 rows. Columns: tissue, what it does. dermal tissue, covers and protects the plant. vascular tissue (xylem and phloem), carries water, minerals and sugars. ground tissue, site of photosynthesis, support and storage.
Zee follows a cell that leaves the shoot tip and becomes part of the tissue where photosynthesis happens. What is true of it?
- It becomes phloem, the tissue that makes the sugars
- It stays in the meristem, where leaf cells keep dividing
- It becomes dermal tissue, which covers and protects the plant
- It becomes ground tissue and stops dividing as it specializes
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.
Ari says dermal tissue cells keep dividing like shoot tip cells. Does the card support this?
- No, permanent tissue cells divide, but more slowly than shoot tip cells
- No, permanent tissue cells have specialized and no longer actively divide
- Yes, a specialized plant cell can divide into any other kind
- No, plants have no cells that keep dividing, so shoot tip cells do not either