Question

Difficulty: HardMulti-Sentence Synthesis Inferences

Passage:
In deep-sea microbial ecology, the 'viral shunt' refers to the process by which viral lysis of marine microorganisms diverts organic carbon from higher trophic levels back into dissolved organic matter. Early oceanographic models assumed that viral lysis in abyssal benthic sediments primarily inhibited long-term carbon sequestration by preventing organic matter from being buried in sub-seafloor strata. However, recent sediment-core analyses reveal a more intricate dynamic: while viral destruction of prokaryotic biomass releases labile nutrients into benthic porewater, it simultaneously stimulates the abiotic polymerization of refractory organic compounds. These recalcitrant complexes resist enzymatic decomposition by benthic bacteria and bind tightly to clay minerals. Consequently, in sediment layers characterized by high viral activity, the rate of persistent organic carbon immobilization is substantially elevated relative to layers dominated by protistan grazing, despite a localized reduction in net microbial biomass creation.

Based on the passage, evaluate whether the following statement is true or false:

Sediment layers in abyssal environments where viral lysis is prevalent retain a higher proportion of carbon in long-term, decomposition-resistant mineral complexes than layers where protistan grazing predominates.

Answer: Answer

Answer

True
The claim is directly supported by combining two distinct sentences in the second half of the passage. The author states that viral lysis generates recalcitrant complexes that resist enzymatic breakdown and bind to clay minerals, and then synthesizes this with the comparative conclusion that carbon immobilization is higher in these layers than in those dominated by protistan grazing.

Step-by-Step Solution

1
Identify the early oceanographic assumption versus the recent empirical finding.
Early models assumed viral lysis hindered carbon sequestration, but recent evidence shows viral lysis stimulates abiotic polymerization of refractory compounds.
Tracking the passage's structural pivot ('However...') is essential to locate the authoritative factual claims.
2
Synthesize the properties of refractory compounds with the comparative impact on sediment layers.
The refractory compounds resist decomposition and bind to clay minerals, leading to elevated persistent organic carbon immobilization in high viral activity layers compared to protistan grazing layers.
Connecting sentence 4 (chemical mechanisms) with sentence 5 (relative immobilization rates) provides the multi-sentence foundation for the statement.
3
Evaluate the statement against the synthesized evidence.
The statement accurately reflects that viral lysis layers retain a higher proportion of carbon in decomposition-resistant mineral-bound forms than protistan grazing layers.
Direct alignment between synthesized passage facts and the claim confirms its truth.

Key Concept

Multi-Sentence Synthesis Inferences
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