Which phase occurs directly after G1

The G1 phase of the cell cycle is followed by the S phase (DNA synthesis).

Explanation:

The interphase of the cell cycle is composed of the G1 phase, the S phase, and the G2 phase.

The G1 phase is characterized, by the cell preparing for the DNA replication, and the centrosomes undergoes replication.

The S phase of the cell cycle during interphase is responsible for the synthesis of DNA. In this phase, the genetic material of the cell is doubled before it enters mitosis or meiosis.