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 dropdown co₂ to dissolve into ocean water and form h₂co₃, which breaks down into h⁺ ions and other ions. as the concentration of h⁺ ions in the water increased, the oceans would become more dropdown. this could cause the shells and exoskeletons of some marine organisms to dropdown.

Explanation:

1. First blank: A rapid increase in atmospheric \( \text{CO}_2 \) leads to more \( \text{CO}_2 \) dissolving in the ocean (since gas dissolves more when atmospheric concentration is higher).
2. Second blank: When \( \text{CO}_2 \) dissolves in water, it forms carbonic acid (\( \text{H}_2\text{CO}_3 \)) which dissociates into \( \text{H}^+ \) ions. An increase in \( \text{H}^+ \) ions lowers the pH (increases acidity), so the ocean becomes more acidic.
3. Third blank: Many marine organisms (like corals, mollusks) have shells/exoskeletons made of calcium carbonate (\( \text{CaCO}_3 \)). In acidic conditions (more \( \text{H}^+ \)), the carbonate ions (\( \text{CO}_3^{2-} \)) react with \( \text{H}^+ \), reducing the availability of carbonate for shell formation. This can cause shells/exoskeletons to dissolve or erode (or become weaker, which can be described as "dissolve" or "erode" depending on context; a common term here is "dissolve" or "erode", and also, the process of shell formation being inhibited can lead to them not forming properly, but in terms of existing shells, acidification causes them to dissolve).

For the first dropdown (how much \( \text{CO}_2 \) dissolves), the answer is "more" (since higher atmospheric \( \text{CO}_2 \) means more dissolves into the ocean). For the second dropdown (ocean's pH change), the answer is "acidic" (because \( \text{H}^+ \) increase lowers pH, increases acidity). For the third dropdown (effect on shells), the answer is "dissolve" (or "erode" or "weaken"; "dissolve" is a common term here as acid reacts with the calcium carbonate in shells).

Answer:

First dropdown: more
Second dropdown: acidic
Third dropdown: dissolve

(Note: Depending on the exact options in the dropdowns, the wording might be slightly different, but the concepts are as above. If the options for the third dropdown include "dissolve", "erode", "weaken", "break down", etc., "dissolve" is a key term here. For the first, "more" \( \text{CO}_2 \) dissolves; for the second, ocean becomes more "acidic".)