Final answer:
The correct answer is 1) Euchromatin, Heterochromatin. Euchromatin is the extended form of chromatin found in the nucleus during interphase, while heterochromatin refers to the highly condensed chromatin form.
Step-by-step explanation:
The extended form of chromatin found in the nucleus during interphase of the cell cycle is called euchromatin; the highly condensed form of chromatin is called heterochromatin. Therefore, the correct answer to the student's question is 1) Euchromatin, Heterochromatin.
Euchromatin is less condensed and represents regions around nucleosomes that are transcriptionally active, meaning that genes in these regions are capable of being expressed or 'turned on.' In contrast, heterochromatin is more densely packed and often contains genes that are not actively transcribed, located at the centromere and telomeres.
DNA in heterochromatin is wrapped around histone proteins to form nucleosomes, which further condense into 30 nm fibers and eventually into the highly condensed chromosomes observed during mitosis and meiosis. This organization allows the DNA to be compacted into the cell nucleus and also plays a role in controlling gene expression and DNA replication.