Question

which of the following correctly matches a nuclear structure with its function?
a nuclear envelope - contains the nucleolar organizer
b nuclear pores - allow molecules to move between the nucleus and cytoplasm
c chromatin - fluid portion of the nucleus
d chromosomes - contains rna and histones
e nucleolus - dna synthesis

Explanation:

• Option A: The nuclear envelope is a double - membrane structure that encloses the nucleus. The nucleolar organizer is a region of a chromosome, not contained within the nuclear envelope.
• Option B: Nuclear pores are protein - lined channels in the nuclear envelope. They regulate the movement of molecules (such as RNA, proteins) between the nucleus and the cytoplasm.
• Option C: Chromatin is a complex of DNA and proteins (including histones). The fluid portion of the nucleus is the nucleoplasm.
• Option D: Chromosomes are made up of DNA and proteins (histones). RNA is not a main component of chromosomes in the way described here.
• Option E: The nucleolus is involved in ribosomal RNA synthesis and ribosome assembly. DNA synthesis occurs in the nucleus (in the case of replication) but not specifically in the nucleolus.

Answer:

B. nuclear pores - allow molecules to move between the nucleus and cytoplasm