how does the nucleus contribute to the transcription and translation of genetic information into proteins.

transcription and translation are known as gene expression. During the process of transcription, the information stored in a gene's DNA is passed to a similar molecule called RNA  in the cell nucleus.  A type of RNA called transfer RNA also known as tRNA assembles the protein, one amino acid at a time.

youre right there are

"do a testcross with a homozygous recessive plant."