Question

1. examine figure 4 and the information on page 224.

a. circle the best choice within the parenthesis to complete the statement: cells that divide more frequently have a cell cycle that is (shorter / the same length / longer) than cells that divide less frequently.
b. why do skin cells divide more frequently than liver cells?
c. why do a child’s cells divide more frequently than an adult’s?

1. examine figure 7 and the information on page 227.

a. how does the cell cycle of cancer cells compare to that of “normal” cells?

Explanation:

a. Cells that divide more frequently need to replicate and replace themselves more quickly, so they have a shorter cell - cycle. Skin cells are constantly exposed to wear and tear and need to be replaced often, while liver cells have a more stable function and don't need as frequent replacement. A child is still growing and developing, so cell division is more rapid to support growth, while an adult's body is mostly in a maintenance phase. Cancer cells have a disrupted cell - cycle regulation and divide more rapidly than normal cells.
b. Skin cells are on the body's surface and are subject to damage, abrasion, and environmental factors. They need to be replaced frequently to maintain the integrity of the skin barrier. Liver cells have a more stable internal environment and are not as exposed to external damage, so they divide less often.
c. A child's body is in a state of growth and development. Cell division is necessary for the growth of tissues and organs, and to replace cells that are used up during normal metabolic processes. In adults, most tissues and organs have reached their full size, and cell division is mainly for repair and maintenance.
d. Cancer cells have a shorter cell - cycle compared to normal cells. They divide uncontrollably due to mutations in genes that regulate the cell - cycle, such as tumor - suppressor genes and proto - oncogenes. This allows them to multiply rapidly and form tumors.

Answer:

a. shorter
b. Skin cells are exposed to more damage and need to be replaced frequently to maintain the skin barrier, while liver cells have a more stable internal environment and are not as exposed to external damage.
c. A child's body is growing and developing, requiring more cell division for growth of tissues and organs, while an adult's body is mainly in a maintenance phase.
d. Cancer cells have a shorter cell - cycle and divide uncontrollably compared to normal cells due to mutations in cell - cycle regulating genes.