Question

nucleus
cytoplasm
structure number 7 is -
a polypeptide chain (protein).
transcription.
a nucleotide.
a dna molecule.

Explanation:

The image depicts the process of protein synthesis. In this process, the ribosome (structure 5) reads the mRNA (messenger RNA) and assembles amino acids (carried by tRNA, structure 6) into a chain. This chain of amino acids is called a polypeptide chain, which eventually folds into a functional protein. Transcription is the process of making RNA from DNA (occurring in the nucleus, involving structure 1 which is likely RNA polymerase). A nucleotide is a single building - block of nucleic acids (like DNA or RNA). A DNA molecule is a double - stranded helical structure (shown in the nucleus). Structure 7 is clearly a chain of amino acids (as indicated by the bead - like structure, each bead representing an amino acid), so it is a polypeptide chain.

Answer:

a polypeptide chain (protein).