# DBT JRF 2022 — Question 144

Exam: DBT JRF 2022 · Section: B · Topic: Environmental Biotechnology › Fungal Biodegradation & Composting · Difficulty: Medium

## Question

Given below are two statements: Statement I: Fungi are important degraders of polymers and are used in the composting and biodegradation of toxic organic substances. Statement II: Fungi are able to selectively excrete toxins present in these polymers. In the light of the above statements, choose the correct answer from the options given below:

## Options

- **A.** Both Statement I and Statement II are true
- **B.** Both Statement I and Statement II are false
- **C.** Statement I is true but Statement II is false
- **D.** Statement I is false but Statement II is true

## Answer

Option C

## Explanation

Fungi as polymer degraders — Statement II is false: Statement I: 'Fungi are important degraders of polymers and are used in composting and biodegradation of toxic organic substances.' — TRUE • White-rot fungi (Phanerochaete chrysosporium): degrade lignin via lignin peroxidase, manganese peroxidase, laccase. • Brown-rot fungi: degrade cellulose and hemicellulose. • Fungi produce extracellular oxidases and hydrolases to break down complex polymers. • Used in bioremediation of PAHs, chlorinated compounds, dyes. Statement II: 'Fungi selectively excrete toxins present in polymers.' — FALSE • Fungi do NOT selectively identify and excrete pre-formed toxins from polymers. • What fungi DO: produce extracellular enzymes that enzymatically cleave the polymer backbone. • The resulting degradation products may be less toxic than the parent compound. • Fungi do not have a toxin-extrusion mechanism specifically for polymer-bound toxins. Answer: Statement I is true (fungi are excellent polymer degraders); Statement II is false (they degrade polymers enzymatically, not selectively excrete toxins).

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