The disease 'pellagra' is caused by the deficiency of: MCQ with Answer and Explanation

Explanation:
The nucleus is bounded by a double membrane called the nuclear envelope, not a single membrane. It houses the nucleolus, which is the site of ribosomal RNA synthesis. The nuclear envelope is perforated by nuclear pores that regulate the bidirectional transport of molecules, including the export of mRNA to the cytoplasm. Thus, statements 2 and 3 are correct.

Explanation:
The poly-A tail is a long chain of adenine nucleotides (typically 100-250) added to the 3' end of a pre-mRNA molecule during post-transcriptional processing in the nucleus. Its primary functions are to protect the mRNA molecule from enzymatic degradation in the cytoplasm (by exonucleases), to facilitate the export of the mature mRNA from the nucleus to the cytoplasm, and to promote translation by helping to recruit ribosomes. It also plays a role in determining the lifespan of the mRNA in the cytoplasm.

Explanation:
Fungi are eukaryotic, mostly multicellular (except yeast), and are heterotrophic by absorption (saprophytic or parasitic). Their cell walls contain chitin. Monera are prokaryotic, Protista are unicellular eukaryotes, Plantae are autotrophic multicellular organisms. Fungi play key roles as decomposers in ecosystems.