Final answer:
During interphase, genetic material is known as chromatin and is not clearly visible under the microscope because it is in a decondensed state. In the G1 phase of interphase, cells prepare for DNA replication by accumulating necessary components and energy.
Step-by-step explanation:
Genetic material is called chromatin during interphase and is not clearly visible. During the G1 phase, the first stage of interphase, the cell is actively engaged at the biochemical level. It's accumulating the building blocks of chromosomal DNA and the associated proteins, as well as energy reserves necessary for the replication of each chromosome in the nucleus. However, the chromatin is in a decondensed, less tightly packed form. This means that it cannot be distinctly observed under the microscope in this phase, making it appear less visible compared to when the chromosomes condense during mitosis.