Consider two mammalian cells, one in G1 and the other in G0 (stationary) phase. If they are stimulated to pass the restriction point (aka START) by the addition of an extracellular proliferation signal, but the signal is then immediately removed, what would you expect to happen?

Both cells will replicate their DNA correct.

Explanation:

Replication is the process by which a double-stranded DNA molecule is copied to produce two identical DNA molecules. DNA replication is one of the most basic processes that occurs within a cell. Each time a cell divides, the two resulting daughter cells must contain exactly the same genetic information, or DNA, as the parent cell. To accomplish this, each strand of existing DNA acts as a template for replication.

"do a testcross with a homozygous recessive plant."