Question

1. a correct balance of oxygen and carbon dioxide must be maintained in the human body to survive. which system is responsible taking in oxygen and releasing carbon dioxide to the external environment to maintain this internal balance? a. the respiratory system b. the circulatory system c. the digestive system d. the nervous system 2. an atom is a single unit of an element. what do we call the next larger unit, which is made up of more than one atom linked together? a. a cell b. a virus c. a molecule d. an electron

Explanation:

1. The respiratory system takes in oxygen and releases carbon - dioxide to maintain the balance of these gases in the body for survival.
2. A molecule is made up of more than one atom linked together. Atoms are the basic units of elements, and when multiple atoms bond, they form a molecule.

Answer:

1. A. the respiratory system
2. C. a molecule