Coronary
arteries supply blood to the heart muscle, The left one, arises from the aorta and
feeds blood to the left side of the heart and the right one supplies blood to
the right ventricle, the right atrium, and the SA (sinoatrial) and AV
(atrioventricular) nodes, which regulate the heart rhythm.
Blockage
in this vessel result in
<span>reducing
the flow of oxygen and nutrients to the heart muscle and that can lead to a
heart attack. Atherosclerosis and arteriosclerosis are the most common causes
of heart disease.</span>
An open circulatory system simply
means that the blood flows out of vessels and into the spaces or sinuses. Invertebrates,
insects and crustaceans has an open circulatory system where pump blood goes
into a hemocoel and diffusing back to the circulatory system between cells. In
other animals, the heart pumps the blood into the body cavities, spaces or
sinuses, where the blood surrounds the tissues.
Answer:
Letter E - exons are cut from the strand and removed
Explanation:
Letter A and B are incorrect because the poly-A tail and guanine cap are added to the 3’ and 5’ end respectively. They aid in translation of the mRNA, while serving as protection. The poly-A tail is repeated adenine nucleotides, while the guanine cap is a modified guanine nucleotide.
Letter C is incorrect because alternative splicing is one mechanism for generating variation, and is thought to be one of the reasons for why humans have smaller genomes than other organisms and still maintain high complexity. Alternative splicing is incredibly important because it produces more than one transcript from a pre-mRNA.
Letter D is incorrect because introns are the non coding portions of the mRNA. They are excised to make a smaller mRNA transcript, and one that contains all the protein genes.
This letter E is the correct answer, because exons are the coding portions of the mRNA, and are not excised during RNA processing.
Hope that helped! If I made a mistake, please let me know.