How cells specialize, and what stem cells are
Grade 9 Science Worksheet - Challenge Me
Circle the best answer.
Read this first
Cycle wheel (model, not to scale), clockwise from the top
G1, S, G2, mitosis (M), cytokinesis. A side branch labeled G0 leaves the wheel near the start of G1. Two branches leave the wheel after G1. Branch A ends at a drawn cell A that is striped, with one nucleus in the middle. Branch B ends at a drawn cell B with a round body, branching projections and one long projection. Genes in cells 1 and 2 (model data), 2 rows. Columns: cell, gene for myosin, gene for a nerve-signal protein. cell 1, on, off. cell 2, off, on. Myosin helps muscle cells contract. On means the cell is using the gene; off means the gene is in the DNA but unused.
Esme joins the drawing and the card. Which statement fits both?
- A matches cell 1, and A and B carry the same DNA but use different genes
- A matches cell 2, since the larger cell is the nerve cell
- A matches cell 1, and B lacks the myosin gene in its DNA
- A matches cell 1, and A and B switch on the same genes at the same time
Off means the gene is in the DNA but unused. Jun joins the drawing and the card. Which statement fits both?
- A and B can still divide into any plant tissue, because specialized cells keep that ability
- The tip's daughter cells specialize into different tissues by using different genes
- A and B differ because the tip hands them different DNA
- A and B cannot come from the tip, since plants have no dividing cells
In cells with a nucleus, genes are used (turned into RNA) inside the nucleus. Pia wants drawn cell A to switch on a new gene. Why can it not do this?
- A is specialized, so it divides into a cell that has a nucleus
- A has different DNA from the cells it came from
- Genes are used in the nucleus, and A has no nucleus, so it has no gene to switch on
- A has switched off its genes for good
Each round, every stem cell makes one stem cell and one specialized cell. Specialized cells do not divide again. Luz works backward from the sample. How many rounds passed, and how many cells are in the sample?
- 5 rounds, and 5 cells in the sample
- 3 rounds, and 4 cells in the sample
- 4 rounds, and 5 cells in the sample
- 4 rounds, and 8 cells in the sample
Two lineages (model data)
round lineage P stem cells lineage Q stem cells lineage Q specialized cells 0 1 1 0 1 2 1 1 2 4 1 2 In lineage P, each stem cell divides into two stem cells. In lineage Q, each stem cell makes one stem cell and one specialized cell.
Milo extends both lineages. After the third round, how many more stem cells does lineage P have than lineage Q?
- 7 more stem cells
- 3 more stem cells
- 8 more stem cells
- 5 more stem cells
Use this
Notebook (model data), 4 rows. Columns: line, what it says. 1, A nerve cell and a muscle cell from one person carry the same DNA. 2, A muscle cell switches on the myosin gene, and a nerve cell leaves it off. 3, A nerve cell has lost the myosin gene, since it does not use it. 4, Two cells of equal size can still be different cell types.
Noah proofreads a notebook about genes. Exactly one line is wrong. Which line, and why?
- Line 3, since an unused gene stays in the DNA
- Line 4, since equal size means equal cell type
- Line 2, since a nerve cell uses its whole set of genes
- Line 1, since cells with different jobs have different DNA
Use this
Notebook (model data), 4 rows. Columns: line, what it says. 1, A stem cell can divide to make more stem cells. 2, Adults do not have stem cells, so bone marrow cannot make new blood cells. 3, Bone marrow stem cells make platelets, red blood cells and white blood cells. 4, Skin epithelial stem cells give rise to keratinocytes.
Pia proofreads a notebook about stem cells. Exactly one line is wrong. Which line, and why?
- Line 3, since a bone marrow stem cell can make any cell in the body
- Line 2, since adult bone marrow does hold stem cells
- Line 4, since skin stem cells give rise to blood cells
- Line 1, since stem cells are found in children but not adults
Tala writes: cells J and K are the same type because both are 10 µm wide. Does the card support this?
- Yes, both have a nucleus, so they are the same type
- No, J and K must carry different DNA, since they are different types
- No, J and K differ in shape and features, which show different types
- Yes, cells of equal width are the same type of cell
The front reads: stem cells from umbilical cord blood are multipotent. The back is blank. Zee writes: multipotent cord blood stem cells can give rise to a nerve cell, a skin cell and a muscle cell. Does the label support this?
- No, a stem cell is already specialized, so it cannot give rise to other cells
- No, multipotent cells give rise to a limited range of related cell types
- Yes, young stem cells are more flexible than adult ones
- Yes, multipotent cells can give rise to any cell type
Use this
Dividing cells in adults and plants (real data, from OpenStax Anatomy and Physiology 2e and Biology 2e), 3 rows. Columns: place, cells that keep dividing. adult bone marrow, hematopoietic stem cells. adult skin, epithelial stem cells. plant shoot and root tips, apical meristem cells, which act like stem cells: they keep dividing and give rise to specialized tissue.
Ari writes: stem cells are found in young animals, so adults and plants have none. Does the card support this?
- Partly: adults have stem cells, but plants have no dividing cells
- Yes, stem cells are found in young animals and are lost with age
- No, since the card lists cells that are already specialized
- No, the card lists stem cells in adults and dividing meristem cells in plants