Question

exam lesson name: introduction to oceanography
exam number: 700793rr
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exam instructions
question 14 of 20 :
select the best answer for the question

1. which of the following accurately describes the distribution of dissolved carbon dioxide gas in the ocean?

a. carbon dioxide levels are highest at the ocean surface, where its produced through photosynthesis.
b. carbon dioxide concentrations decrease with depth due to more uptake and decomposition of organic matter at depth.
c. carbon dioxide levels are lowest at the ocean surface, where its produced through decomposition.
d. carbon dioxide concentrations increase with depth due to less uptake and decomposition of organic matter at depth.
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Explanation:

• Analyze Option A: Photosynthesis consumes \( \text{CO}_2 \), so surface \( \text{CO}_2 \) should be lower (not highest) from photosynthesis. Eliminate A.
• Analyze Option B: Decomposition of organic matter at depth releases \( \text{CO}_2 \), so \( \text{CO}_2 \) should increase with depth (not decrease). Eliminate B.
• Analyze Option C: Decomposition is more common at depth, and surface has photosynthesis (consumes \( \text{CO}_2 \)), so surface \( \text{CO}_2 \) is low, but it's not produced by decomposition at the surface. Eliminate C.
• Analyze Option D: At depth, there is less photosynthetic uptake (since light is limited) and more decomposition of organic matter (sinking from surface) which releases \( \text{CO}_2 \), so \( \text{CO}_2 \) concentrations increase with depth. This matches.

Answer:

D. Carbon dioxide concentrations increase with depth due to less uptake and decomposition of organic matter at depth.