for each of the following, state whether it is an organelle , a cell , a tissue , an organ , an organ system, or an organism a) heart b) trachea c) onion epidermis d) onion bulb e) onion plant f) human being g) lung

b heart because it is connected to the organelles

before it leaves the nucleus of a eukaryotic cell, mrna is altered in the following ways: - a cap is added to the 5' end of the mrna molecule; - a poly a tail is added to the 3' end; - introns are removed and exons are spliced together.