If a eukaryotic cell is in the G1 phase of the cell cycle, which statement about the cell’s chromosomes must be correct?

Question

Each chromosome consists of two identical chromatids.
Each chromosome is made of a complex of DNA and associated proteins.
The chromosomes are preparing for DNA synthesis.

Answer 1

In the G1 phase of the cell cycle, the following statement about the cell's chromosomes must be correct:

Each chromosome is made of a complex of DNA and associated proteins.

During the G1 phase, the cell is in the process of growth and preparing for DNA synthesis, but the chromosomes do not yet consist of two identical chromatids. Each chromosome consists of a single, unreplicated strand of DNA (called a chromosome) and has not yet undergone the replication that would lead to sister chromatids, which occurs during the S phase of the cell cycle. Therefore, the other two statements are not correct for cells in the G1 phase:

1. Each chromosome consists of two identical chromatids - Incorrect (this happens after replication in S phase).
2. The chromosomes are preparing for DNA synthesis - Partially correct in that the cell is preparing for DNA synthesis, but it is not the chromosomes themselves that are preparing; rather, the whole cell prepares for the upcoming S phase.

So, the only unequivocally correct statement in the context of the G1 phase is about the structure of the chromosomes being made of DNA and proteins.