Question

The DNA in some lung cells was damaged by the carcinogenic compounds in tobacco and apoptosis was initiated. Which of the following is the best way for the damaged lung cells to send a message to their neighboring cells that they need to increase the production of DNA repair enzymes or start apoptosis as well?
A) They should send signaling molecules into the bloodstream.
B) They should send signaling molecules through the gap junctions.
C) They should send signaling molecules across a small extracellular space.
D) They should send signaling molecules by secreting them into the local environment.

Answer 1

Answer:

C) They should send signaling molecules across a small extracellular space.

Explanation:

To send a message to nearby cells, signal molecules only need to cross a small amount of space. Bloodstream (choice A) is used for long-distance communication, choice D is too vague, and choice B is used only for cells that are directly touching each other.

Answer 2

Answer:

B) They should send signal molecules through the gap junctions.

Explanation: