Question

how might a rapid increase in atmospheric co₂ levels affect marine organisms? complete the paragraph.
a rapid increase in atmospheric co₂ levels would cause more co₂ to dissolve into ocean water and form ▼, which breaks down into h⁺ ions and other ions. as the concentration of h⁺ ions in the water increased, the oceans would become ▼ acidic. this could cause the shells and exoskeletons of some marine organisms to ▼.

Explanation:

1. When \( \text{CO}_2 \) dissolves in ocean water, it reacts with \( \text{H}_2\text{O} \) to form carbonic acid (\( \text{H}_2\text{CO}_3 \)): \( \text{CO}_2 + \text{H}_2\text{O}

ightleftharpoons \text{H}_2\text{CO}_3 \). So the first blank is "carbonic acid".

1. Carbonic acid (\( \text{H}_2\text{CO}_3 \)) dissociates into \( \text{H}^+ \) and \( \text{HCO}_3^- \) (and further into \( \text{CO}_3^{2-} \)). An increase in \( \text{H}^+ \) ions increases the acidity (lowers pH) of the ocean, so the second blank is "more" (as the oceans become more acidic).
2. The increased acidity (lower pH) affects the availability of carbonate ions (\( \text{CO}_3^{2-} \)), which are used by organisms like corals, mollusks, etc., to build their shells (made of calcium carbonate, \( \text{CaCO}_3 \)). The reaction \( \text{CaCO}_3 + \text{H}^+

ightarrow \text{Ca}^{2+} + \text{HCO}_3^- \) can occur, leading to the dissolution (or weakening) of the shells/exoskeletons. So the third blank is "dissolve" (or "weaken", but "dissolve" is more direct in this context of acid - shell interaction).

Answer:

First blank: carbonic acid; Second blank: more; Third blank: dissolve