Question

which of the following is an example of an external checkpoint of the cell cycle? *
p. g1 checkpoint
q. g2 checkpoint
r. m checkpoint
s. hormones
which checkpoint tries to make sure that the correct amount of dna (number of chromosomes) is being divided into each cell?
a. g1 checkpoint
b. g2 checkpoint
c. m checkpoint
d. t checkpoint

Explanation:

• For the first question:
• \(G1\), \(G2\), and \(M\) checkpoints are internal checkpoints of the cell cycle.
• Hormones are external signals that can influence the cell cycle.
• For the second question:
• The \(M\) checkpoint (also known as the spindle - assembly checkpoint) ensures that chromosomes are properly attached to the spindle fibers and that the correct amount of DNA (number of chromosomes) is being divided into each cell.
• The \(G1\) checkpoint checks for cell size, nutrients, growth factors, and DNA damage.
• The \(G2\) checkpoint checks for DNA replication completeness and DNA damage.
• There is no \(T\) checkpoint in the standard cell - cycle checkpoints.

Answer:

1. S. Hormones
2. C. M checkpoint