Question

complete each statement by selecting the appropriate word or phrase in each drop - down. 1. cell division may be initiated by (click to select) replication. 2. chemical signals called (click to select) may stimulate cell division. 3. when cells (click to select), neighboring cells may be stimulated to divide. 4. cell division stops due to (click to select).

Explanation:

1. DNA replication occurs in the interphase of the cell cycle, and its completion is a key trigger for the initiation of cell division.
2. Growth factors are extracellular chemical signals that bind to cell surface receptors to activate pathways promoting cell division and proliferation.
3. When cells die (e.g., due to injury or apoptosis), signals are released to stimulate neighboring cells to divide and replace the lost cells, maintaining tissue integrity.
4. Density-dependent inhibition is a regulatory mechanism where cells stop dividing when they come into contact with nearby cells, preventing overcrowding in tissues.

Answer:

1. Cell division may be initiated by DNA replication.
2. Chemical signals called growth factors may stimulate cell division.
3. When cells die, neighboring cells may be stimulated to divide.
4. Cell division stops due to density-dependent inhibition