How cells specialize, and what stem cells are
Grade 9 Science Worksheet - Challenge Me
Circle the best answer.
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
- A and B cannot come from the tip, since plants have no dividing cells
- A and B differ because the tip hands them different DNA
- The tip's daughter cells specialize into different tissues by using different genes
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 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
- A is specialized, so it divides into a cell that has a nucleus
Read this first
Stem cell rounds with growth (model data)
round stem cells specialized cells 0 1 0 1 2 0 2 2 2 In the first round, the stem cell divides into two stem cells. In later rounds, each stem cell makes one stem cell and one specialized cell. Specialized cells do not divide again. Every cell keeps its nucleus and gets a copy of its parent's DNA.
Kira continues the table to the third round. How many cells then carry a copy of the first stem cell's DNA?
- 4 cells, the number of specialized cells made
- 2 cells, since specialized cells get different DNA
- 6 cells, since every daughter gets a copy of the DNA
- 8 cells, since each of the 4 cells divides again
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?
- 3 rounds, and 4 cells in the sample
- 4 rounds, and 5 cells in the sample
- 4 rounds, and 8 cells in the sample
- 5 rounds, and 5 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?
- 3 more stem cells
- 8 more stem cells
- 5 more stem cells
- 7 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 2, since a nerve cell uses its whole set of genes
- Line 1, since cells with different jobs have different DNA
- Line 4, since equal size means equal cell type
- Line 3, since an unused gene stays in the 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 1, since stem cells are found in children but not adults
- Line 2, since adult bone marrow does hold stem cells
- Line 3, since a bone marrow stem cell can make any cell in the body
- Line 4, since skin stem cells give rise to blood cells
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
- Yes, cells of equal width are the same type of cell
- No, J and K differ in shape and features, which show different types
- No, J and K must carry different DNA, since they are different types
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, multipotent cells give rise to a limited range of related cell types
- No, a stem cell is already specialized, so it cannot give rise to other cells
- 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?
- 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
- Partly: adults have stem cells, but plants have no dividing cells