# DBT JRF 2022 — Question 142

Exam: DBT JRF 2022 · Section: B · Topic: Environmental Biotechnology › Hydrocarbon Degradation Pathways · Difficulty: Medium

## Question

Which one of the following process is NOT used to convert the hydrocarbons present in the organic compounds to central metabolic intermediates?

## Options

- **A.** Hydration
- **B.** Extraction
- **C.** Nitroreduction
- **D.** Reductive dehydroxylation

## Answer

Option B

## Explanation

Extraction is NOT a biochemical conversion of hydrocarbons: Hydrocarbon biodegradation involves enzymatic conversion of organic hydrocarbons to central metabolic intermediates (e.g., acetyl-CoA, TCA cycle intermediates). The processes include: • Hydration: addition of water across a C=C double bond; e.g., alkene → alcohol. • Nitroreduction: reduction of nitro groups (−NO₂ → −NH₂) in nitroaromatic compounds; key in degradation of TNT, nitrobenzene. • Reductive dehydroxylation: removal of a hydroxyl group under anaerobic conditions; e.g., phenol → benzene in some anaerobic pathways. Extraction: • Extraction is a PHYSICAL SEPARATION process (liquid-liquid or solid-liquid extraction). • It separates compounds based on differential solubility between two phases. • It does NOT chemically transform hydrocarbons — no covalent bonds are made or broken. Therefore, extraction is NOT used to convert hydrocarbons to metabolic intermediates. Answer: Extraction is a physical separation, not a biochemical conversion; it does not convert hydrocarbons to metabolic intermediates.

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