Download 2.1 Check your understanding 1. Cells divide to repair damaged or

2.1 Check your understanding
1. Cells divide to repair damaged or worn-out cells, to increase the number of
cells so the organism can grow, and for reproduction.
2. Cell division increases the number of cells, making the organism larger.
3. Cell reproduction could repair/replace damaged nerve cells.
4. Skin cells wear out faster than other cells because they experience more wear
and tear.
5. Cells inside the mouth and bone marrow cells that produce new blood cells
are examples of regions with rapid cell divisions.
6. It takes a long time to add muscle to a body or heal broken bones.
7. (a) repair (b) repair/regeneration (c) reproduction (d) growth
8. Red blood cells last about four months, so everybody’s blood is about the
same age.
9. Skin cells wear out faster than muscle cells. Muscle cells are more specialized
than skin cells so do not divide as fast.
10. Not all cells undergo division; red blood cells do not reproduce, and the cells of
the brain and spinal cord (the central nervous system) do not reproduce under
normal circumstances.
11. As a cell grows, the volume of cytoplasm increases at a greater rate than the
surface area of the cell. Once a cell grows beyond a certain size, it cannot
function efficiently.
12. As in question 11, there is a limit to cell size. A large organism has more cells,
not bigger cells.
13. Bacteria and yeast use cell division for reproduction.
14. After six divisions, 12 cells would become 768 cells.