Answer:
Some causes can be heart disease, cancer, lung ailments, accidents, cirrhosis of the liver.
Answer:
is a highly glycosylated and big type I transmembrane fusion protein that is made up of 1,160 to 1,400 amino acids, depending upon the type of virus.
Explanation:
The answer here would be true
The second statement best explains the type of blood vessel and the function of these vessels' valves - <span>These are veins, which prevent the backflow of blood because the walls have little muscle to pump blood back to the heart.
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Veins are large blood vessels which carry blood back to the heart. <span>Veins have a system of valves to prevent back-flow.</span>
