Q.171 Zoology ⭐ 360° Option Elimination Active

NEET 2021 Zoology Question 171 Solution

Topic: Microbes in Human Welfare · Official NTA Booklet Code M1

Question

Match List - I with List - II. (a) Aspergillus niger (i) Acetic Acid (b) Acetobacter aceti (ii) Lactic Acid (c) Clostridium butylicum (iii) Citric Acid (d) Lactobacillus (iv) Butyric Acid List - I List - II Choose the correct answer from the options given below. (a) (b) (c) (d)

(1)(iii) (i) (iv) (ii)
(2)(i) (ii) (iii) (iv)
(3)(ii) (iii) (i) (iv)
(4)(iv) (ii) (i) (iii)

✓

Verified Against NTA Final Answer Key

Option (1) : (a)-(iii), (b)-(i), (c)-(iv), (d)-(ii)

📚 Microbes in Human Welfare Easy

📋 Given Parameters & Problem Setup

List I (Microorganisms) (a) Aspergillus niger, (b) Acetobacter aceti, (c) Clostridium butylicum, (d) Lactobacillus

List II (Organic Acids) (i) Acetic Acid, (ii) Lactic Acid, (iii) Citric Acid, (iv) Butyric Acid

⚡

The 30-Second Exam Hall Shortcut: ⚡ "Match Root Names: Acetobacter → Acetic, Clostridium butylicum → Butyric"

⏱️ Save ~25 seconds

The organism names directly reveal their acids: Acetobacter aceti -> Acetic acid ((b)-(i)), Clostridium butylicum -> Butyric acid ((c)-(iv)), and Aspergillus niger -> Citric acid ((a)-(iii)). Looking at options, only Option (1) matches!

1 Match by name: Acetobacter aceti -> Acetic acid ((b) -> (i)).

2 Match by name: Clostridium butylicum -> Butyric acid ((c) -> (iv)).

3 Match Lactobacillus -> Lactic acid ((d) -> (ii)).

4 Match Aspergillus niger (fungus) -> Citric acid ((a) -> (iii)).

5 Match pattern (iii), (i), (iv), (ii) -> Option (1).

🛡️

Why You Can 100% Trust This Shortcut: NCERT Biology · Microbes in Human Welfare (Chemicals, Enzymes and other Bioactive Molecules: Aspergillus niger (a fungus) of citric acid, Acetobacter aceti (a bacterium) of acetic acid, Clostridium butylicum (a bacterium) of butyric acid and Lactobacillus (a bacterium) of lactic acid).

📐

Step-by-Step Rigorous Workflow & Mathematical Proof

Step 1

Microbial Organic Acid Producers in Industrial Biotechnology

Microbes are utilized commercially for the aerobic and anaerobic fermentation of organic acids: - (a) *Aspergillus niger*: A filamentous ascomycete fungus; primary industrial producer of Citric Acid (used as an acidifier and preservative in food/beverages). - (b) *Acetobacter aceti*: An obligate aerobic bacterium; oxidizes ethanol into Acetic Acid (vinegar). - (c) *Clostridium butylicum*: An obligate anaerobic endospore-forming bacterium; ferments carbohydrates to produce Butyric Acid. - (d) *Lactobacillus*: Lactic acid bacteria (LAB); converts lactose/glucose into Lactic Acid.

\begin{aligned} \textit{Aspergillus niger} &\longrightarrow \textbf{Citric Acid} \quad [\text{(a)} \to \text{(iii)}] \\ \textit{Acetobacter aceti} &\longrightarrow \textbf{Acetic Acid} \quad [\text{(b)} \to \text{(i)}] \\ \textit{Clostridium butylicum} &\longrightarrow \textbf{Butyric Acid} \quad [\text{(c)} \to \text{(iv)}] \\ \textit{Lactobacillus} &\longrightarrow \textbf{Lactic Acid} \quad [\text{(d)} \to \text{(ii)}] \end{aligned}

Step 2

Option Alignment

The combined match is (a)-(iii), (b)-(i), (c)-(iv), (d)-(ii). This corresponds precisely to Option (1).

⭐

360° Option Elimination Engine Key Feature

Diagnose every choice: Know exactly why the right option works and why distractors fail.

4-Option Deep Scan

1 1

✓ 100% Correct

Verdict & Scientific Reason:

Correct. Perfectly aligns every microbe with its corresponding organic acid product.

💡

Why this is airtight: None. Candidate recognizes the classical microbial fermentation pairs.

2 2

✗ Incorrect

Verdict & Scientific Reason:

Incorrect. Assigns acetic acid to Aspergillus niger and lactic acid to Acetobacter aceti.

⚠️

Student Fallacy (Why candidates pick this trap): Reading list entries sequentially without matching.

3 3

✗ Incorrect

Verdict & Scientific Reason:

Incorrect. Misattributes lactic acid to Aspergillus and citric acid to Acetobacter.

⚠️

Student Fallacy (Why candidates pick this trap): Confusing fungal citric acid production with bacterial lactic fermentation.

4 4

✗ Incorrect

Verdict & Scientific Reason:

Incorrect. Links Aspergillus niger to butyric acid.

⚠️

Student Fallacy (Why candidates pick this trap): Complete confusion of microbial taxonomy.

⚠️

NTA Trap Alert: Fungus vs Bacterium Identity Trap

Aspergillus niger is the sole fungus in this list, producing citric acid. Candidates sometimes confuse Aspergillus with bacteria and match it with butyric acid.

🛡️ How to avoid the -1 mark: Remember: Aspergillus niger = Citric acid fungus; the other three are bacteria with names reflecting their products (aceti = acetic, butylicum = butyric, lacto = lactic).

📖

Core NEET Syllabus Standard

NEET / NCERT Biology · Microbes in Human Welfare Standard Benchmark

Core Scientific Principle Tested:

"Aspergillus niger produces citric acid; Acetobacter aceti produces acetic acid; Clostridium butylicum produces butyric acid; Lactobacillus produces lactic acid."

Syllabus Focus: Chemicals, Enzymes and other Bioactive Molecules

✓ Core NEET UG Syllabus Anchor Syllabus & Academic Standards ↗

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NEET 2021 Zoology Question 171 Solution

Question

The 30-Second Exam Hall Shortcut: ⚡ "Match Root Names: Acetobacter → Acetic, Clostridium butylicum → Butyric"

Step-by-Step Rigorous Workflow & Mathematical Proof

Microbial Organic Acid Producers in Industrial Biotechnology

Option Alignment

360° Option Elimination Engine Key Feature

NTA Trap Alert: Fungus vs Bacterium Identity Trap

Core NEET Syllabus Standard

Ready to attempt under real exam pressure?

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