During the summer, they spread across the tundra in smaller groups to feed. In fall, they group together again into larger herds for breeding. They stay in these larger groups throughout their winter migration to the “taiga” regions which are the areas just south of the tundra.
An embolus <span>occurs when a clot breaks free from an artery wall and travels through the circulatory system until it lodges in a small artery and suddenly shuts off blood flow to the tissues.</span>
DNA ligase is an enzyme that connects nucleotides of DNA from the phosphate to the sugar. This seems to match the provided description, therefore I believe it to be the correct answer.
