When do the respiratory and circulatory systems work together?
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a. to stop bleeding
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b. to promote digestion
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c. to supply nutrients
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d. to fight infections

halogen, any of the six nonmetallic elements that constitute group 17 (group viia) of the periodic table. the halogen elements are fluorine (f), chlorine (cl), bromine (br), iodine (i), astatine (at), and tennessine (ts).

essentially, one bacterial cell splits into two daugurer cells. bacterial offspring don't need or get care from their parents because they are in a sense their own parents. that said, some bacteria can and do depend on other bacteria especially in harsh environments such as bacterial microfilms in hot water tanks.