When the solute concentration of a solution increases,

A. Addition of a water molecule between each two units: Adding water breaks bonds during hydrolysis, so this process does not synthesize carbohydrates or proteins but rather breaks them down.

B. Removal of a carbon atom between each two units: Synthesis does not involve removing carbon atoms. The carbon skeleton of monomers remains intact when forming polymers.

C. Removal of a water molecule between each two units: Condensation (or dehydration) reactions synthesize carbohydrates and proteins by linking monomers. Each bond formation releases a water molecule, connecting sugars into polysaccharides or amino acids into polypeptides.

D. Addition of a carbon atom between each two units: Carbon atoms are not added during polymerization; the existing carbon atoms in monomers are used to form the polymer chain.

A. Maintaining boundaries: Maintaining boundaries refers to the separation between internal and external environments, such as the plasma membrane or skin, and is not directly related to removing carbon dioxide.

B. Excretion of metabolic waste: Expiration removes carbon dioxide, a byproduct of cellular respiration, from the body. This is a primary example of excreting metabolic waste to maintain proper internal chemical balance.

C. Responsiveness: Responsiveness is the ability of the body to detect and react to changes in the environment, such as moving away from a stimulus, which does not involve carbon dioxide removal.

D. Metabolism: Metabolism encompasses all chemical reactions in the body, including producing carbon dioxide as a byproduct. However, the act of exhaling carbon dioxide specifically exemplifies waste excretion, not metabolism itself.