Rna Transcription

Let's break down each statement: (A) "Transport of pre-mRNA to cytoplasm prior to splicing" is incorrect. Splicing and other modifications (such as capping and polyadenylation) occur in the nucleus before the mRNA is transported to the cytoplasm.
(B) "Removal of introns and joining of exons" is correct. This is a key post-transcriptional event called RNA splicing, which happens in the nucleus.
(C) "Addition of methyl group at 5' end of hnRNA" is correct. This process is called 5' capping, and it helps protect the mRNA and facilitates its recognition by the ribosome.
(D) "Addition of adenine residues at 3' end of hnRNA" is correct. This is the polyadenylation process, which adds a poly-A tail to the mRNA, aiding in stability and transport.
(E) "Base pairing of two complementary RNAs" is incorrect. This is not a post-transcriptional event, but it may occur during translation or RNA interference processes. Thus, the correct answer is B, C, D only.